Article

Influence of free-choice vs mixed-ration diets on food intake and performance of fattening calves

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Abstract

Research findings and management recommendations typically emphasize responses of the "average" individual, yet more than half of the animals in a group may differ significantly from the mean regarding food preference and intake. The productivity of a herd may be adversely affected if animals differing from the mean are fed a uniform diet formulated to meet the needs of the "average" individual. We compared the intake and performance of beef calves offered a choice or no choice among foods. Diets consisted of ad libitum access to either a chopped, mixed ration of rolled barley (31.3%), rolled corn (31.3%), corn silage (15.5%), and alfalfa hay (18.9%) (n = 16 calves) or a choice among those foods offered individually (n = 15 calves). Averaged across the 63-d trial, the two groups did not differ in ratios of protein to energy ingested (43 vs 43 g CP/Mcal ME; P = 0.50), but preference for foods high in energy or protein varied markedly for animals fed free-choice: on d 21 they had protein:energy ratios higher than those of animals fed the mixed ration, on d 2 the ratios were equal, and on d 40 they had protein:energy ratios lower than those of animals fed the mixed ration. Throughout the trial, no two animals consistently chose the same ingredients, and none selected a diet similar to the nutritionally balanced mixed ration, yet each animal ate a diet adequate to meet its needs. Animals offered the mixed ration tended to eat more than animals offered a choice (109 vs 102 g/kg MBW/d; P = 0.10), but they did not gain at a faster rate (0.89 vs 0.92 kg/d; P = 0.65). Gain/unit of food consumed also was similar for both groups (0.09 vs 0.10 kg/kg; P = 0.38). However, food cost/day was higher for animals fed the mixed ration than for those offered a choice ($1.58 vs $1.36; P = 0.03). Consequently, cost/kilograms of gain was higher for the mixed ration than for the choice group ($1.84 vs $1.49/kg; P = 0.045). These findings suggest that 1) animals can more efficiently meet their individual needs for macronutrients when offered a choice among dietary ingredients than when constrained to a single diet, even if it is nutritionally balanced; 2) transient food aversions compound the inefficiency of a single mixed diet by depressing intake even among animals suited to that nutritional profile; and 3) alternative feeding practices may allow producers to efficiently capitalize on the agency of animals, thus reducing illness and improving performance.

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... Even if animals given a free choice do not eat more or show higher levels of production than those offered a mixed feed, there can still be economic benefits associated with offering dietary choice. Atwood et al. (2001) found that beef calves offered dietary choice showed similar intakes and weight gains to those on a mixed ration, but the feed cost per day was higher for animals on the mixed ration ($1.58 d (1 ) compared with those offered a choice ($1.48 d (1 ). As a result, feed cost per unit weight gain was higher ($1.84 kg (1 ) in animals on the mixed diet compared with those offered a choice ($1.49 kg (1 ). ...
... As a result, feed cost per unit weight gain was higher ($1.84 kg (1 ) in animals on the mixed diet compared with those offered a choice ($1.49 kg (1 ). Atwood et al. (2001) argued that these economic benefits were due to the animals on choice diets being able to select nutrients and/or to avoid toxins depending on their individual requirements and experiences, something that the animals on the mixed ration were unable to achieve. ...
... In other situations, e.g., low nutritional requirements or animals fed cut forage or silage with a high intake rate potential, there does not appear to be any intake or production benefit. However, as Atwood et al. (2001) demonstrated, there can still be economic benefits to offering dietary choice. There may also be other advantages to feeding ruminant livestock separate feeds, and these will be discussed in the following two sections. ...
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The evolutionary and domestic ancestors of sheep and cattle will have evolved diet selection behaviours that enabled them to select a diet that met their individual nutrient requirements whilst minimising the risk of being killed through predation or by eating toxins. Modern intensive farming generally involves grazing monocultures or feeding total mixed rations and these restrict the ability of livestock to select their own diet. Research has shown that grazing sheep andcattle have a partial preference of approximately 70% for clover (when offeredas a monoculture sward alongside grass), and they show a consistent diurnal pattern of preference. Dairy cattle and sheep that are given the ability to select their own diet show higher levels of production than animals grazing mixed swards. There is some evidence that animals that can select their own diet are optimising their own efficiency of nutrient capture, and this potential environmental benefit warrants further research. Further research is also needed to establish if dairy cattle "need" to graze or whether they prefer to eat prepared rations indoors. Preventing animals from expressing their innate diet preferences by feeding them mixed rations may cause frustration and so compromise animal welfare, although this hypothesis requires further research.
... When offered a choice lambs are able to select a ration with constant CP:energy ratio meeting their demand (Provenza et al. 1996). Several times it has been shown that ruminants selected a ration balanced for macronutrient in response to their (changing) demand from different feedstuffs (Kyriazakis and Oldham 1993;Scott and Provenza 2000;Atwood et al. 2001) enabling individual animals to meet their nutritional requirements more precisely than with a constant mixed ration prepared for the herd or group. This is also true for concentrates as long as the animals had the chance for appropriate adaptation with learning about the post-ingestive feedback of those energy-or protein-rich ingredients (Atwood et al. 2001). ...
... Several times it has been shown that ruminants selected a ration balanced for macronutrient in response to their (changing) demand from different feedstuffs (Kyriazakis and Oldham 1993;Scott and Provenza 2000;Atwood et al. 2001) enabling individual animals to meet their nutritional requirements more precisely than with a constant mixed ration prepared for the herd or group. This is also true for concentrates as long as the animals had the chance for appropriate adaptation with learning about the post-ingestive feedback of those energy-or protein-rich ingredients (Atwood et al. 2001). ...
... Ruminants that got used to diverse feedstuffs early in life are better in regulating intake of concentrates and roughages to match individual needs (Atwood et al. 2001). It also enhances acceptance of novel foods when compared to animals that were reared on monotonous rations (Catanese et al. 2012). ...
Book
Habilitation thesis, summary: Ruminants are essential in the supply of high-quality foods such as meat and milk for a growing human population. However, ruminants are also a main source of greenhouse gas and nitrogen (N) emissions into the environment. In three chapters, the contribution of forage conservation and ruminant nutrition to a more efficient and sustainable use of natural resources is discussed. A major influencing factor is reduction of losses from harvest to digestion by the animal. Chapter 1 focusses on aspects of impacting losses occurring during forage conservation and the feeding value of preserved forages by means of different treatments. Two publications describe changes in the feeding value taking place during fermentation and aerobic exposure of forages and draw conclusions how to consider them in ration for ruminants. In chapter 2, different possibilities are described how the nutrition of ruminants can help to improve the efficient use of resources. One distinct advantage of ruminants over monogastric animals is that they can utilize grazed grass, forages and coproducts being unsuitable for human consumption. For maximizing intake and increasing the share of forage in ruminant rations forage quality is of foremost concern. Besides chemical composition and digestibility of nutrients also the type and composition of carbohydrate and protein sources can affect feeding behavior as they impact both the postingestive feedback as well as the motivation for feed intake. Also sensory characteristics are of special relevance in forage choice, especially for the case of fermented feedstuffs containing numerous volatile organic compounds. In this regard, two publications focus on possibilities of impacting the feed acceptance and intake behavior of ruminants and furthermore, suitable experimental designs are discussed. Nitrogen is typically not used efficiently in ruminant production systems and in chapter 3, possibilities for improvement are discussed. Decreasing dietary intake of crude protein turned out to be the most effective way. As soon as supply with essential amino acids becomes limiting, supplementing individual rumen-protected amino acids is a further promising approach, albeit with a number of constraints. Two publications use condensed tannins as secondary plant compounds in an attempt to impact rumen metabolism, nutrient digestion and productivity of dairy cows and sheep. Another publication studies the origin of the gaseous, climate-relevant nitrous oxide emitting from ruminants and discusses mitigation strategies for reducing N losses during conservation. The combination of described approaches in forage conservation as well as in ration formulation to reduce losses and to more precisely meet the requirements of ruminants offers great potential to contribute to a more efficient and sustainable use of natural resources.
... Dietary diversity in ruminants has recently received considerable attention in the literature (1)(2)(3)(4)(5)(6)(7)(8). Much of this work has focused on how dietary diversity can improve animal production by providing animals with the opportunity to choose and mix their diets. ...
... As ruminant nutritionists, requirements are typically assessed and food offered to meet those requirements for an average animal. However, if we expect dietary requirements to follow a normal distribution, a small number of animals would be "average" and thus, ∼50% of animals will be fed diets that under supply nutrients and around 50% will over ingest nutrients (1,2). Therefore, lack of dietary choice may result in individual dietary imbalances. ...
... In an early experiment, reduced dry matter intake, similar performance, and improved feed efficiency were observed when dairy cows were offered forage and grain separately as opposed to being provided a total mixed ration (109). Another experiment conducted in feedlot fed steers provides further evidence for this hypothesis (2). Cattle were offered either a total-mixed ration or the components of the total-mixed ration offered individually. ...
Article
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Ruminants evolved in diverse landscapes of which they utilized, by choice, a diverse arrangement of plants (grasses, forbs, and trees) for food. These plants provide them with both primary (carbohydrates, protein, etc.) and secondary (phenolics, terpenes, etc.) compounds (PPC and PSC, respectively). As no one plant could possibly constitute a "balanced-diet," ruminants mix diets so that they can exploit arrangements of PPC to meet their individual requirements. Diet mixing also allows for ruminants to ingest PSC at levels, acquiring their benefits such as antioxidants and reduced gastrointestinal parasites, without overstepping thresholds of toxicity. Meeting dietary requirements is assumed to provide satisfaction through achieving positive internal status and comfort, thereby a sense of hedonic (happiness through pleasure) well-being. Furthermore, choice including dietary choice is a factor influencing well-being of ruminants in a manner akin to that in humans. Choice may facilitate eudaimonic (happiness through pursuit of purpose) well-being in livestock. Nutritional status plays an integral role in oxidative stress, which is linked with illness. Several diseases in livestock have been directly linked to oxidative stress. Mastitis, metritis, hypocalcaemia, and retained placenta occur in animals transitioning from dry to lactating and have been linked to oxidative stress and such a stress has likewise been linked to diseases that occur in growing livestock as well, such as bovine respiratory disease. The link between physiological stress and oxidative stress is not well-defined in livestock but is evident in humans. As dietary diversity allows animals to select more adequately balanced diets (improved nutrition), take advantage of PSC (natural antioxidants), and allows for choice (improved animal well-being) there is a strong possibility for ruminants to improve their oxidative status and thus health, well-being, and therefor production. The purposes of this review are to first, provide an introduction to oxidative and physiological stress, and nutritional status as effected by dietary diversity, with special attention to providing support and on answering the "how." Second, to provide evidence of how these stresses are connected and influence each other, and finally discuss how dietary diversity provides a beneficial link to all three and enhances both eudaimonic and hedonic well-being.
... Therefore, assessing dietary preferences of calves raised under intensive conditions, offered a range of diet components often used by the industry, should give us insight into (realistically achievable) diet compositions that could maximise calf welfare. Ruminants generally choose an array of different diet components to meet their nutritional requirements (Provenza, 1995;Atwood et al., 2001). This is explained by their need for various feed characteristics for nutrient uptake, a process that depends not only on the nutrient content of the feed but also on good rumen health, which is itself dependent on fermentable fibre content of the feed, feed structure and rumination. ...
... Ruminants also display different dietary preferences at different times of day (Atwood et al., 2001;Manteca et al., 2008). Moreover, postingestive cues are important in the establishment of dietary preferences (Favreau et al., 2010), which explains why young ruminants may need to go through a trial and error learning phase before selecting appropriate diets (Provenza and Balph, 1987). ...
... adequate levels of rumination) and health (e.g. optimum rumen development) compared to when fed a mixed ration, and should, therefore, result in improved welfare of each and every individual (Atwood et al., 2001;Manteca et al., 2008). ...
Article
Calves raised for milk or meat are fed diets that differ from feral-herd calf diets and are based on the nutritional requirements of the ‘average calf’. These diets may not meet the dietary preferences of each individual calf. This study explored diet preferences in calves with free dietary choice, and the effect of these preferences on behaviour. Group-housed Holstein-Friesian bull calves (N = 23) were given unlimited access to five diet components (i.e. milk replacer [MR], concentrate, maize silage, long hay and long barley straw). At 3 and 6 months of age, calves were moved for 7 days to an automated test pen in groups of four, where intake, time spent eating, and visit frequency to each diet component was recorded to assess preferences. Behaviour was recorded on 2 of the 7 days in the test pen, from 07:30 to 18:00 h using instantaneous scan sampling for periods of 30 min every 2.5 h at a 2 min interval. Solid feed intake at 6 months averaged 3205.5 ± 174.6 g DM.d−1. At 3 months, calves selected the following proportion of MR, concentrate and roughage in relation to total g DM intake: 51.6 ± 5.0%, 25.0 ± 4.7% and 23.4 ± 2.8%. At 6 months, the calves conserved the roughage proportion (23.3 ± 1.6%), but increased concentrate intake (47.1 ± 2.1%) at the expense of MR (29.6 ± 1.9%). Order of preference for the five diet components varied according to whether intake, time spent eating each component, or visit frequency was considered. On the whole, MR was preferred followed by concentrate and hay at both ages. Offering a dietary choice led to large individual variation in intake and to 47% to 80% calves with the same ranking as the average ranking for diet components. This suggests diets based on the ‘average calf’ may meet only few calves’ dietary preferences. Different variables showed different preference rankings and studies in the future should consider the relative importance of these variables in assessing animal preferences.
... However this conventional feeding system does not allow for differences between individual animals. As many as half of animals within a particular group may differ significantly from the mean (Atwood et al. 2001). Therefore when fed a single diet pigs of below average growth rate may consume more protein than they can use, while pigs of above average growth rate may over eat in an effort to consume enough protein to meet their higher requirements and as a result deposit more fat. ...
... Diet selection results in a systematic decline of the protein concentration of the diet selected with time (Engelke et al. 1984, Kyriazakis et al. 1990, Bradford and Gous 1991a,b and 1992, and Kyriazakis et al. 1993). Choice-fed pigs (Nam et al. 1995) and calves (Atwood et al. 2001) tend to eat less, have lower total protein intake (Nam et al. 1995), and less 10 th rib fat (Bradford and Gous 1991a, Kyriazakis et al. 1993, and Nam et al. 1995) when compared to those animals fed a single mixed ration diet. ADG is not effected by feeding system, single vs. free choice, (Engelke et al. 1984, Bradford and Gous 1991b, and Atwood et al. 2001. ...
... Choice-fed pigs (Nam et al. 1995) and calves (Atwood et al. 2001) tend to eat less, have lower total protein intake (Nam et al. 1995), and less 10 th rib fat (Bradford and Gous 1991a, Kyriazakis et al. 1993, and Nam et al. 1995) when compared to those animals fed a single mixed ration diet. ADG is not effected by feeding system, single vs. free choice, (Engelke et al. 1984, Bradford and Gous 1991b, and Atwood et al. 2001. The results of Nam et al. (1995) showed gilts fed free choice selected a diet containing 14.7% CP which was less than the single fed gilts (15.2% CP). ...
Article
Three experiments were conducted to determine the effect of body composition on the diet selected by finishing pigs. In Exp. 1 and 2 pigs were sorted into body composition groups based on ultrasound scans at the 10 th rib. In Exp. 3, barrows were randomly assigned to one of four dietary treatments. Lean gilts (Exp. 1) consumed more of the high protein diet (63.9%) than did Fat gilts (31.5%), resulting in differences in percent protein consumed. Lean barrows (Exp. 2) consumed 70.6% of the high protein diet whereas Fat barrows consumed 56.9%, but this did not result in significantly different percent protein consumed. Barrows in Exp. 3 self-selected a 16.7% CP diet, which was different from the 15.6% CP Mix diet treatment. The results suggest that allowing animals to self-select may reduce nitrogen intake, nitrogenous excretion, cost of production, and negative environmental impact.
... However, the effects of feeding behavior on gastrointestinal function in cattle are less understood. Previous studies reported that ruminants allowed to choose among ingredients were able to select diets according to their needs (Atwood et al., 2001;Moya et al., 2011). Moreover, when sodium bicarbonate is offered as a choice, ruminants select a diet that attenuates ruminal acidosis (James and Kyriazakis, 2002;Phy and Provenza, 1998a,b). ...
... When the components of the diet were offered separately, feedlot cattle were able to regulate their daily intake and feeding behavior for each ingredient depending on the dietary components offered. In agreement with previous studies (Atwood et al., 2001;Moya et al., 2011;Bach et al., 2012), these results suggest that ruminants allowed to choose among ingredients are able to regulate feed intake according to their needs. ...
... at Canadian Agriculture Library on October 17, 2014 www.journalofanimalscience.org Downloaded from process to the new diet and feeding system, cattle fed the BGCS and BGDG treatments maintained the same ADG and G:F as those fed the TMR. Others have shown similar results in beef cattle fed a free-choice diet vs. a TMR (Atwood et al., 2001;Sahin et al., 2003;Moya et al., 2011). In the context of this relatively short feeding period, the lack of difference in the performance parameters among those treatments leads to the conclusion that offering grain and forage components separately enabled the heifers to select their own diet without negatively affecting performance relative to a TMR diet. ...
Article
Full-text available
Seventy-nine continental crossbred beef heifers (524.4 ± 41.68 kg BW), 16 of which were ruminally cannulated, were used in a 53-d experiment with a generalized randomized block design, to assess the effects of barley-grain, corn silage and corn distillers' grain offered in a free-choice diet on feeding behavior and ruminal fermentation. Treatments were: total mixed ration (TMR) consisting of 85% barley-grain (BG), 10% corn silage (CS), and 5% supplement); or free-choice (i.e., self-selection) diets of barley-grain and corn silage (BGCS); corn dry distillers' grain (DG) and barley-grain (BGDG); or corn silage and corn distillers' grain (CSDG). Heifers were housed in groups of 9 or 10 in 8 pens and weighed 2 h prior to feed delivery at d 0, 21, 42, and 52 of the study. Pens were equipped with an electronic feed bunk monitoring system enabling feed intake and feeding behavior to be continuously monitored. Each of these pens were randomly allocated two cannulated heifers equipped with indwelling pH probes for continuous measurement of ruminal pH during wk 1, 2, 4 and 7. Blood and rumen contents were taken from cannulated heifers 2 h post feed delivery on d -3, 0, 7, 8, 42, and 49. Cattle fed either TMR or free-choice diets had similar (P > 0.10) ruminal fermentation, blood profile, and growth performance, with the exception of the CSDG diet for which ruminal pH levels were consistently greater (P < 0.01), and performance was lower (P < 0.01). When DG was a component in free-choice diets, heifers reduced its inclusion in the diet (P < 0.05) over the experiment without affecting growth rate or ruminal fluid pH. Finishing feedlot cattle fed BG and CS separately, selected a diet with a greater proportion of BG (85% DMI) compared to the TMR with no signs of acidosis. When cattle were given free-choice access to corn dry distillers' grain as an alternative to CS, they consumed levels up to 30% of their total daily DMI. Under the conditions of our experiment cattle can effectively self-select diets without increasing the risk of subclinical acidosis and still maintain similar levels of growth and feed efficiency compared with a TMR.
... Results of numerous experimental studies confirm that also cattle modify several aspects of feeding behaviour to prevent physiological disturbances, such as low ruminal pH. Fattening calves offered free-choice of different feeds, including easily fermentable grain, did not develop acidosis (Atwood et al. 2001). Moreover, all animals in the study were able to ingest proper amounts of nutrients and maintain rumen pH in physiological limits, but no two animals chose the same amounts of different ingredients. ...
... Interestingly, the rate of body weight gain did not differ between these two groups. During the experiment no individual routinely selected the same feeds and none consumed a diet similar to nutritionally balanced TMR (Atwood et al. 2001). All these results highlighted the pronounced role of individual variability in food choice. ...
... Therefore, appropriate nutrition for the average animal may not be accurate for specific individuals. If animals differing from the mean are fed a uniform diet formulated to meet the needs of the average individual, some of them may suffer from the hunger, other from negative consequences of overeating, all of which have the adverse effects on the productivity (Atwood et al. 2001). An alternative for prescribing the averaged ration for all the animals is individualization of feeding which would include current nutritional requirements of the individual. ...
Article
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One of the largest challenges for the dairy industry is to provide cows with a diet which is highly energetic but does not negatively affect their rumens' functions. In highly productive dairy cows, feeding diets rich in readily fermentable carbohydrates provides energy precursors needed for maximum milk production, but simultaneously decreases ruminal pH, leading to a widespread prevalence of subacute ruminal acidosis. Maximizing milk production without triggering rumen acidosis still challenges dairy farmers, who try to prevent prolonged bouts of low ruminal pH mainly by proper nutrition and management practices. The animals try to avoid overeating fermentable feeds, as it causes negative consequences by disturbing digestive processes. The results of several experiments show that ruminants, including sheep and beef cattle, are able to modify some aspects of feeding behaviour in order to adjust nutrient intake to their needs and simultaneously prevent physiological disturbances. Particularly, such changes (e.g., increased preference for fibrous feeds, reduced intake of concentrates) were observed in animals, which were trying to prevent the excessive drop of rumen fluid pH. Thanks to a specific mechanism called "the postingestive feedback", animals should be able to work out such a balance in intake, so they do not suffer either from hunger or from negative effects of over-ingesting the fermentable carbohydrates. This way, an acidosis should not be a frequent problem in ruminants. However, prolonged periods of excessively decreased rumen pH are still a concern in dairy cows. It raises a question, why the regulation of feed intake by postingestive feedback does not help to maintain stable rumen environment in dairy cows?
... By mixing diets through choice, individual requirements for nutrients (under the right circumstances), medicines and prophylactics are better met, reducing incidental restriction and augmentation Gregorini et al., 2017). This is supported by feed conversion efficiency increments with the availability to choose dietary components freely (Nocek et al., 1986;Atwood et al., 2001Atwood et al., , 2006Yurtseven and Görgülü, 2004). Thus, increasing their ability to meet individual specific requirements, would result in a more positive internal state and would increase the hedonic value of their diets, thereby improving animal well-being and welfare. ...
... Another argument against nutritional wisdom in ruminants used by Schingoethe (2017) is works which have shown that when animals are allowed free choice between the forage and concentrate the cows consumed in excess of their requirements and milk production was not increased compared with TMR fed cows (based on a 1927 experiment, which we could not obtain, but was cited by Spahr, 1977). However, several experiment have shown improvements in feed efficiency by allowing animals free choice between the forage and concentrate portions of the rations (Nocek et al., 1986;Atwood et al., 2001Atwood et al., , 2006Yurtseven and Görgülü, 2004). Further support for ruminants' nutritional wisdom is found in experiments which explore the sorting behavior of TMR fed cattle. ...
... Also meeting individual requirements may increase positive emotions that enhance hedonic well-being, can improve animal welfare and subsequently performance. This is supported by both the experiments of Villalba et al. (2012) and Catanese et al. (2013) who reported that lambs offered diverse diets had lower blood cortisol and several studies which have provided dietary choice to ruminants and determined performance benefits (Nocek et al., 1986;Atwood et al., 2001Atwood et al., , 2006Yurtseven and Görgülü, 2004). Additionally, Villalba et al. (2012) found a tendency for greater rates of gain by the lambs offered choice compared with those provided the monotonous diet. ...
Article
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Pastoral livestock production systems are facing considerable societal pressure to reduce environmental impact, enhance animal welfare, and promote product integrity, while maintaining or increasing system profitability. Design theory is the conscious tailoring of a system for a specific or set of purposes. Then, animals-as biological systems nested in grazing environments-can be designed in order to achieve multi-faceted goals. We argue that phytochemical rich diets through dietary taxonomical diversity can be used as a design tool for both current animal product integrity and to develop future multipurpose animals. Through conscious choice, animals offered a diverse array of plants tailor a diet, which better meets their individual requirements for nutrients, pharmaceuticals, and prophylactics. Phytochemical rich diets with diverse arrangements of plant secondary compounds also reduce environmental impacts of grazing animals by manipulating the use of C and N, thereby reducing methane production and excretion of N. Subsequently functional dietary diversity (FDD), as opposed to dietary monotony, offers better nourishment, health benefits and hedonic value (positive reward increasing "liking" of feed), as well as the opportunity for individualism; and thereby eudaimonic well-being. Moreover, phytochemical rich diets with diverse arrangements of plant secondary compounds may translate in animal products with similar richness, enhancing consumer human health and well-being. Functional dietary diversity also allows us to design future animals. Dietary exposure begins in utero, continues through mothers' milk, and carries on in early-life experiences, influencing dietary preferences later in life. More specifically, in utero exposure to specific flavors cause epigenetic changes that alter morphological and physiological mechanisms that influence future "wanting," "liking" and learning of particular foods and foodscapes. In this context, we argue that in utero and early life exposure to designed flavors of future multifunctional foodscapes allow us to graze future ruminants with enhanced multiple ecosystem services. Collectively, the strategic use of FDD allows us to "create" animals and their products for immediate and future food, health, and wealth. Finally, implementing design theory provides a link between our thoughtscape (i.e., the use of FDD as design) to future landscapes, which provides a beneficial foodscape to the animals, an subsequently to us.
... Some studies have reported that ruminants are able to select a diet that attenuates possible subclinical acidosis when cattle are given the opportunity of choosing among different ingredients separately (Cummins et al., 2009; Moya et al., 2011). In addition, when offered ad libitum access to individual feedstuffs, ruminants (10 mo old or older) seem to be able to regulate feed consumption according to their needs (Forbes and Provenza, 2000; Atwood et al., 2001; Askar et al., 2006; Bach et al., 2012) but not at early ages (Miller-Cushon et al., 2014). Feeding HMC separately from the 2 other dietary components (concentrate and straw) could be a plausible alternative to reduce feeding costs without increasing farm investments. ...
... Different protein to starch (ME) ratios and protein to energy synchronies among treatments can be observed and the interpretation of their relationship with the performance results can be very complex. The hypothesis that animals select a diet balanced for macronutrients in response to their changing requirements (Atwood et al., 2001 ) may need to be further contrasted, as number (affects possible combinations) and type of feeds (different preferences and energy, protein, and fiber content) offered differ among studies. Concentrate intake was reduced when HMC (ground or whole) was fed in a free-choice situation together with concentrate and straw compared with heifers fed only concentrate and straw, so the objective of finding a strategy to reduce concentrate intake was achieved.. ...
Article
The objectives of this study were to evaluate the effects of high-moisture corn (HMC), either whole or ground, fed separately from concentrate and straw on feeding behavior, rumen fermentation, whole tract digestibility, and nitrogen balance. Twenty-four Holstein heifers (199 ± 5.5 kg BW and 157 ± 6.9 d age) housed in individual pens were assigned to 3 treatments: 1) whole (unprocessed) HMC fed along with concentrate and barley straw, all fed separately and ad libitum (WHMC); 2) HMC ground through a 0.4-cm screen before ensiling and fed along with concentrate and barley straw, all fed separately and ad libitum (GHMC); and 3) a concentrate composed of mainly corn meal, ground through a roller mill with screen openings of 6 mm, and barley straw, both fed separately and ad libitum (Control). Concentrate, HMC, and straw were offered separately ad libitum in a free-choice situation and consumption was recorded daily and BW was recorded weekly. Apparent nutrient digestibility and N balance were determined at the beginning, middle, and end of the study. At the same time points, rumen fluid was collected through rumenocentesis to determine rumen pH and VFA concentrations. Feeding behavior was monitored throughout the study. Animals were harvested after 134 d and HCW, rumen and cecum wall lesions, and liver abscesses were recorded. Treatment did not affect total DMI, feed efficiency, ADG, final BW, and carcass weight or classification. Concentrate consumption (6.6 ± 0.35 kg/d) of Control heifers was greater ( < 0.001) than that of GHMC (4.1 ± 0.35 kg/d) and WHMC heifers (2.8 ± 0.35 kg/d), and GHMC heifers consumed less ( < 0.001) HMC than WHMC heifers (2.3 ± 0.31 and 4.2 ± 0.31 kg/d, respectively). Dietary treatments did not affect rumination, self-grooming, nonnutritive oral behaviors, and rumen pH. However, rumen acetate to propionate ratio decreased when heifers received HMC (1.77 ± 0.276) compared with when heifers received the Control (2.82 ± 0.276). Total tract starch apparent digestibility was greater in Control (97.7 ± 0.47%) and GHMC heifers (99.4 ± 0.47%) than in WHMC heifers (95.2 ± 0.47%), although an interaction between treatment and time was observed ( < 0.01). Treatments did not affect N retention. Feeding HMC, either whole or ground, separately from concentrate and straw resulted in performance and behavioral patterns similar to feeding only concentrate and straw.
... Concordantly, by providing ruminants a variety of feeds, they are able to select a diet that meets their nutritional needs (Villalba and Provenza 1996) and promote optimal rumen function (Phy and Provenza 1998). Atwood et al. (2001) and Moya et al. (2014) showed that free-choice-fed beef steers were able to select dietary ingredients without increasing the risk of acidosis or decreasing the production level compared with steers fed a TMR. Also, no differences in animal performance were observed when comparing roughage delivery separately from concentrate components of the diet versus TMR in beef (Keane et al. 2006;Huuskonen et al. 2014) and dairy cattle (Holter et al. 1977). ...
... These results were consistent with previous findings, where feeding dairy/beef cattle the components of the ration either separately or totally mixed resulted in similar intake parameters (Holter et al. 1977;Arroquy et al. 2012). Also, free choice-fed cattle, even when eating less feed, have shown daily weight gains similar to those of TMR-fed cattle (Atwood et al. 2001;Arroquy et al. 2006). Furthermore, we found that feeding the fibre fraction discontinuously (every 3 or every 6 days) did not change intake parameters and ruminal function. ...
Article
The inclusion of fibre in a total mixed ration (TMR) often has operational and economic constraints. The objective of the present study was to compare intake and ruminal fermentation of steers fed either a TMR or a diet with the fibre fraction fed separately from the concentrate fraction. Six ruminally fistulated steers were used in a six-treatments, four-period cross-over experiment. Treatment structure was a 3 × 2 factorial. The first factor was fibre delivery either as a part of a TMR or offered separately from the concentrate fraction once every 3 or 6 days. The second factor was represented by two fibre sources, namely, alfalfa hay or cotton by-products. Fibre delivery and source did not significantly affect total, concentrate, fibre and digestible dry-matter intake, compared with TMR. A similar response was observed for ruminal pH, ammonia concentration and total volatile fatty acid concentration. Intake of crude protein and fibre, as well as the concentration of total volatile fatty acids, were higher for alfalfa hay than for cotton by-products. In conclusion, feeding the fibre portion separately from the concentrate fraction once every 3 or 6 days did not negatively affect intake and rumen function compared with when a TMR was fed, regardless of fibre source.
... It has long been assumed that animals select diets that optimize nutrient intake and minimize anti-nutrients intake (Freeland and Janzen, 1974;Westoby, 1978;Atwood et al., 2001;Behmer et al., 2002). Jansen et al. (2007) tested the maximization of nutrient intake and the minimization of anti-nutrients (plant secondary compounds) intake hypotheses. ...
... Determining browse selection is an important prerequisite for assessing the impacts of browsers on their environments and understanding plant-herbivore interactions (Tanentzap et al., 2009). Factors that drive browse selection are complex and remain poorly understood, although it has long been assumed that animals select diets that optimize nutrient intake and minimize intake of anti-nutrients (Atwood et al., 2001;Behmer et al., 2002). Plants need to protect themselves against loss of valuable nutrients and photosynthetic tissue to herbivores (Rosenthal and Janzen, 1979). ...
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Browse selection is viewed as the process by which herbivores balance the twin goals of nutrient maximization and anti-nutrient (plant secondary compounds) minimization. This study investigated how browsers maximize nutrient intake and minimize intake of plant secondary compounds. Free ranging Matebele goats were observed foraging in open savanna woodland which had woody species that produce all their new leaves on old lignified shoots or branches (shoot-limited, SL) (Terminalia prunioides and Commiphora pyracanthoides) and those that produce all their new leaves on new growing shoots (shoot-dominated, SD) (Grewia monticola, G. tenax and Colophospermum mopane). The following, crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), condensed tannins (CT), total phenolics (TP), digestibility and rumen fermentation of the woody species were determined to explain the browse selection patterns of the goats. The instantaneous intake rates of the woody species were also determined and related to leaf size, thorn density and leaf accessibility. The influence of leaf maturity on CP, NDF, ADF, CT, TP, digestibility and rumen fermentation of the woody species was also studied. The browse selection indices (BSI) of SL species (Terminalia prunioides and Commiphora pyracanthoides) were higher (1.80 vs 0.36) than those of SD species (Grewia monticola, G. tenax and Colophospermum mopane). Foliage of SD species is exposed to herbivory while that of SL species is protected by lignified branches that are spinescent in some species. Shoot-limited species had lower neutral detergent fibre (410 vs 550 g/kg dry matter), acid detergent fibre (240 vs 350 g/kg dry matter) and condensed tannins (0.40 vs 15.5 g/kg of dry matter) contents than SD species. Shoot-limited species had higher in vitro dry matter digestibility (0.54 vs 0.43) and in vitro gas production (69 vs 33 ml/300mg after 48 hours) than SD species. Small leaf and high thorn density reduced instantaneous intake rate (IIR) while high leaf accessibility, calculated as inter-thorn spacing divided by mean goat muzzle width, increased IIR. Crude protein (CP) content of woody species declined with leaf maturity, NDF and ADF increased with leaf maturity, while CT and TP showed no clear trend. Terminalia prunioides was the most digestible and C. pyracanthoides the most fermentable while D. cinerea had the lowest digestibility and rumen fermentation. The Matebele goats selected SL over SD species presumably because of their lower chemical defences (NDF, ADF and CT contents). The SD species were better chemically defended than SL species which depended on physical defences. The CT, NDF and ADF contents of the browse had an inverse relationship with browse digestibility and rumen fermentation. The goats were able to maximize nutrient intake and minimize plant secondary compounds intake, through selecting T. prunioides and C. pyracanthoides which had high digestibility and rumen fermentation and low CT, ADF and NDF contents.
... Sin embargo, la forma de ofertar el alimento, sea como dieta completa o como concentrado separado del alimento voluminoso, no tuvo efecto en la ganancia de peso diaria. Esto coincide con lo informado por Atwood et al. (2001), Simeone et al. (2007) y Anderson (2007), quienes no refieren efecto de la forma de ofertar el alimento en este indicador. Maekawa et al. (2002) encontraron mayor estabilidad en los valores de pH ruminal cuando se ofertó dieta integral. ...
... Se utilizó 12 % menos del alimento con respecto a este estudio, donde además el alimento voluminoso representó 49 % del total ingerido por el animal. Atwood et al. (2001) necesitaron 11.2 kg de alimento para ganar 1 kg de peso vivo cuando emplearon dieta completa y cuando ofrecieron los alimentos por separado, solo utilizaron 10.1 kg de alimento, lo que representó un valor más próximo al obtenido en este experimento. ...
Article
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Instituto de Ciencia Animal Cuba Rodríguez, D.; Martín, P.C.; Alfonso, F.; Enríquez, Ana V.; Sarduy, Lucía Forraje de caña de azúcar como dieta completa o semicompleta en el comportamiento productivo de toros mestizos Holstein x Cebú
... Lambs fed a uniform diet with no opportunity for choice had slower feed intakes than did those allowed to choose between feeds that varied over time, as well as higher cortisol levels and neutrophil to lymphocyte ratios, suggesting that they might have been experiencing stress (Catanese et al. 2013). Consistent with the hypothesis that cattle prefer variety, all beef heifers tested consumed more than one type of feed when they are offered a choice (Ginane et al. 2002), and calves select different dietary ingredients day to day and at different times of day (Atwood et al. 2001). Cows have approximately 20,000 taste receptors on their tongues, compared to less than 7,000 for humans and 1,700 for dogs (reviewed by Roura et al. 2008), suggesting they may be highly attuned to distinctions in flavour, and perhaps prone to boredom when fed monotonous diets. ...
... It has also been suggested that allowing individuals to choose their own diets is valuable because physiological needs differ across individuals (Atwood et al. 2001, Manteca et al. 2008. This assumes that animals have some level of 'nutritional wisdom' and are able to select feeds based on the nutrients they require; there is some evidence to support this view (Manteca et al. 2008). ...
Article
Motivation to explore is believed to be widespread among animals, but exploratory behaviour varies within populations. Offering variety in feed is one simple way of allowing intensively housed dairy cattle to express exploratory foraging behaviour. Individuals’ exploration of different feed types, as with other new stimuli, likely reflects a balance between exploratory motivation and fear of novelty. We tested the degree to which Holstein heifers (n = 10) preferred variety in feed vs. a constant, high quality mixed ration, by first providing varying types of forages and then varying flavours of mixed feed. We also investigated individual differences in exploratory behaviour by measuring switching between feed bins. Individual consistency in preferences was assessed between tests, and longer-term consistency was evaluated by comparing these results with behaviour in novel object and novel feed tests before weaning. On average, the heifers preferred the constant, familiar feed (spending on average just 20% of their time at varied feed bins), but this preference varied among individuals (from 0 to 46% of time eating in the forage trial, and 0 to 93% in the flavour trial). Preference for varied forages correlated positively with intake of novel feed as calves (rs = 0.72, n = 9). Preference for varied flavours showed a negative correlation with latency to approach a novel object (rs = −0.65). It thus appears that preference for variety and exploratory foraging behaviour reflect consistent personality traits. These results suggest that offering novel feeds on a rotating schedule as a supplement to the regular diet may be an effective form of enrichment for at least some individuals within a herd.
... Lambs and goats fed with ingredient separately, simultaneously and ad libitum (choice-feeding or cafeteria feeding) have been shown to be able to meet their nutrient requirements by selecting a diet corresponding to their physiological status and environmental conditions [3,4]. Choice-fed calves may be able to select a more nutritious diet than TMR fed calves receiving calf grower and hay in total mixed ration, in addition to maximizing their nutrient intake [5], and when given a free choice, young calves have been shown to preferentially consume milk replacer, followed by concentrate and roughage [6]. Individual variation in dietary choices has been observed; Gorgulu et al. [7] showed that choice-fed calves in pre-weaning period selected a diet containing higher crude protein (CP) (31 to 35%) than a standard starter protein level (18%) and that this preference was not changed after 2 weeks from weaning. ...
... In the current study, the choice-fed calves selected a more nutritious diet than the calves fed with TMR and maximized their nutrient intake. Atwood et al. [5] reported that animals with the opportunity to select their diet from multiple choices maximized their energy intake. Although, the calves in the choice fed group had no previous experience of diet preference, they successfully chosen the nutritious diets meeting their nutrient requirements. ...
... Keywords: beef cattle, growth traits, carcass traits, meat quality, tanninAtwood et al. (2001), estudaram o efeito de diferentes formas de fornecimento da ração (volumoso e concentrado fornecidos de forma conjunta ou separada). Da mesma forma, LaManna et al. (2012)estudaram o efeito de diferentes formas de fornecimento da ração sobre o desempenho e a qualidade da carne de novilhos cruzados em fase de terminação e não verificaram efeito da forma e oferecimento do volumoso sobre o ganho de peso e características da carne. ...
... Para o ganho de peso médio diário, houve interação entre o tipo de sorgo e forma de fornecimento da ração, sendo que, os animais que receberam silagem de grão de sorgo de baixo teor de tanino com volumoso separado apresentaram maior ganho de peso médio diário (P=0,003) em comparação aos animais alimentados com o mesmo tipo de silagem de grão de sorgo, mas com o volumoso misturado (Tabela 4). Em trabalhos que utilizaram diferentes formas de fornecimento de ração, como as utilizadas no presente estudo, não foram observadas diferenças sobre o ganho de peso médio diário (ATWOOD et al., 2001;COLLARES et al., 2008;La MANNA et al., 2012). De acordo comMcSweeney et al. (2001), o tanino pode reduzir a digestão da fibra, podendo diminuir o consumo de matéria seca. ...
Article
This work aimed to evaluate three varieties of sorghum as wet grain silage (high, low and white tannin), combined with two form of food supply (concentrated with roughage separated or mixed) on dry matter intake, body weight evolution, average daily growth, feed conversion, main meat and carcass traits (rib eye area, fat thickness and marbling in vivo and post mortem) in Hereford-Angus crossbred steers. Forty eight males castrated with 20 months of age were used, divided into randomized blocks, arranged in a 3 × 2 factorial. The regression coefficients for the weight gain of each treatment was compared using orthogonal contrasts. Dry matter intake was affected by the type of sorghum (P=0.002) and the form of food supply (P=0.0005). The form of food supply can interfere with the dry matter intake (P=0.0001) and weight (P=0.0001). Feed
... Differences among individuals in food preferences depend on variation in form and function, and marked differences are common even among 'uniform' groups of animals in their needs for nutrients (Scott and Provenza 1999) and abilities to cope with secondary compounds (Provenza et al. , 1992. Thus, variation among individuals can affect production of the group if the diet diverges much from what individuals at the extremeswhich can be as much as half of the groupprefer and can tolerate (Scott and Provenza 1999;Atwood et al. 2001;Provenza et al. 2003). ...
... Consequently, few have asked whether intake can decline, and performance and health improve, if animals have access to a variety of phytochemically rich foods, which presumably satiate by meeting the needs of cells? The study of Atwood et al. (2001) suggested that this may be the case for livestock; cattle offered a choice of four foodsrolled barley, rolled corn, corn silage and alfalfa hayate less, but grew equally well, that did cattle fed a total mixed ration made of these four foods in proportions formulated to meet the needs of the 'average individual' in the study. In this and other studies reviewed by Provenza and Villalba (2006), livestock can over-eat to meet needs for limiting nutrients. ...
Article
Herbivores make decisions about where to forage and what combinations and sequences of foods to eat, integrating influences that span generations, with choices manifest daily within a lifetime. These influences begin in utero and early in life; they emerge daily from interactions among internal needs and contexts unique to biophysical and social environments; and they link the cells of plants with the palates of herbivores and humans. This synthesis summarises papers in the special issue of Animal Production Science that explore emerging understanding of these dynamics, and suggests implications for future research that can help people manage livestock for the benefit of landscapes and people by addressing (1) how primary and secondary compounds in plants interact physiologically with cells and organs in animals to influence food selection, (2) temporal and spatial patterns of foraging behaviours that emerge from these interactions in the form of meal dynamics across landscapes, (3) ways humans can manage foraging behaviours and the dynamics of meals for ecological, economic and social benefits, and (4) models of foraging behaviour that integrate the aforementioned influences.
... Differences among individuals in food preferences depend on variation in form and function, and marked differences are common even among 'uniform' groups of animals in their needs for nutrients (Scott and Provenza 1999) and abilities to cope with secondary compounds (Provenza et al. , 1992. Thus, variation among individuals can affect production of the group if the diet diverges much from what individuals at the extremeswhich can be as much as half of the groupprefer and can tolerate (Scott and Provenza 1999;Atwood et al. 2001;Provenza et al. 2003). ...
... Consequently, few have asked whether intake can decline, and performance and health improve, if animals have access to a variety of phytochemically rich foods, which presumably satiate by meeting the needs of cells? The study of Atwood et al. (2001) suggested that this may be the case for livestock; cattle offered a choice of four foodsrolled barley, rolled corn, corn silage and alfalfa hayate less, but grew equally well, that did cattle fed a total mixed ration made of these four foods in proportions formulated to meet the needs of the 'average individual' in the study. In this and other studies reviewed by Provenza and Villalba (2006), livestock can over-eat to meet needs for limiting nutrients. ...
Article
Herbivores make decisions about where to forage and what combinations and sequences of foods to eat, integrating influences that span generations, with choices manifest daily within a lifetime. These influences begin in utero and early in life; they emerge daily from interactions among internal needs and contexts unique to biophysical and social environments; and they link the cells of plants with the palates of herbivores and humans. This synthesis summarises papers in the special issue of Animal Production Science that explore emerging understanding of these dynamics, and suggests implications for future research that can help people manage livestock for the benefit of landscapes and people by addressing (1) how primary and secondary compounds in plants interact physiologically with cells and organs in animals to influence food selection, (2) temporal and spatial patterns of foraging behaviours that emerge from these interactions in the form of meal dynamics across landscapes, (3) ways humans can manage foraging behaviours and the dynamics of meals for ecological, economic and social benefits, and (4) models of foraging behaviour that integrate the aforementioned influences.
... Within a species, it has been demonstrated that domestic and wild individuals (sheep, goats, fallow deer) display different preferences for protein to energy ratio to meet their needs (Atwood et al. 2001), but also that they can respond differently to plant secondary compounds (Provenza et al. 2003, Bergvall 2009). Hence, individual differences in diet selection criteria could also be observed for chamois and mouflon as we noticed a relatively high amongindividual variation at the taxonomic level. ...
... Ainsi, une autre exploration idéale serait de mener des études longitudinales dans le but de suivre des individus sur une longue période de temps, à travers l'identification génétique des faeces, et étudier la variation intra-individuelle des régimes. d) Lier la β-diversité taxonomique et fonctionnelle Au sein d'une espèce, il a été démontré que les individus domestiques et sauvages (moutons, chèvres, daims) montrent différentes préférences pour les ratios protéines/énergie pour atteindre leurs besoins (Atwood et al. 2001), mais aussi qu'ils peuvent répondre différemment aux composés secondaires des plantes (Provenza et al. 2003, Bergvall 2009). Ainsi, des différences individuelles dans les critères de sélection alimentaire pourraient être observées chez le chamois et le mouflon comme il a été noté une relativement forte variabilité inter-individuelle au niveau taxonomique. ...
Thesis
Given the key role of large herbivores on species and functional plant diversity, we aimed at better understanding the relationship between herbivory and plant communities mainly at a fine-scale, in order to reconcile objectives of population management and plant conservation. For this purpose, we used both taxonomic and functional approaches, and studied interactions at the inter- and intra-specific levels. We combined information coming from three databases: (1) diet data from DNA-metabarcoding applied on chamois (Rupicapra rupicapra), roe deer (Capreolus capreolus) and mouflon (Ovis gmelini musimon) faeces from the Bauges Massif, (2) characteristics of plant communities (plant composition, biomass, phenology), (3) plant functional traits. Analyses of intra-specific variability of the three large herbivores allowed us to upscale the niche variation hypothesis (NVH) of Van Valen from the intra- to the inter-specific level, i.e. we observed a positive relationship between the species niche breadth and among-individual variation. Then, based on two chamois subpopulations living in pastures, one living in sympatry with the mouflon and the other living in allopatry, we revealed the absence of negative effects of the introduced mouflon population on native chamois population diet, both for the taxonomic and functional dietary niche. Analyses of diet selection criteria allowed us to highlight differences in choice criteria between chamois and mouflon in some seasons, which helped to explain the taxonomic and functional niche partitioning of the two species. Furthermore, the proposed scenario of the evolution of diet selection over the year for both species were consistent with ungulate-specific morpho-physiological features. Finally, contrary to the literature where no studies could discriminate the direct and indirect effects of functional traits on diet selection because of correlations, we used path analyses, which allowed us to show that in most cases, biomechanical traits had a direct effect on diet choices, whereas chemical traits had an indirect effect. Furthermore, from a methodological point of view, we advised to use nitrogen fecal indices only to study the evolution of species-specific and location-specific population long-term diet quality, but not to compare diet quality between species, nor to study slight fluctuations at the intra-seasonal level. The complementarity of the approaches allowed us to better account for the structuration of herbivore communities, which should help to better assess the actual state and the evolution of relationships among individuals, species and their environment.Key-words: ungulates, intra- and inter-specific interactions, taxonomic and functional approach, DNA metabarcoding, NIRS, Bauges Massif, diet selection
... Feeding method did not affect ADG and G:F ratio of beef heifers when concentrate and barley straw were offered separately as a free-choice or as a TMR. These results agree with those reported by other authors (Atwood et al., 2001;Moya et al., 2011). Atwood et al. (2001) compared the performance of fattening calves given ad libitum access to either a mixed ration of Table 6. ...
... These results agree with those reported by other authors (Atwood et al., 2001;Moya et al., 2011). Atwood et al. (2001) compared the performance of fattening calves given ad libitum access to either a mixed ration of Table 6. Fatty acid profile (g/100 g of total fatty acids) of the Longissimus thoracis muscle of heifers fed concentrate and barley straw offered as a free choice diet (FCH) or as a total mixed ration (TMR) Feeding method in feedlots time (min) = 233.9 ...
Article
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Eighteen Simmental heifers were fed concentrate and barley straw offered as a total mixed ration (TMR) or separately as a free choice (FCH) to compare performance, behaviour, and meat quality. The heifers were assigned to treatments in a randomized complete block design. Animals were allotted to roofed pens with 3 animals per pen, and 3 pens per treatment. Intake of concentrate, average daily gain, and gain to feed ratio were not different between diets, being on average 7.6 kg/day, 1.38 kg/day and 0.18 kg/kg, respectively. Straw intake was greater in TMR than in FCH treatment (0.7 vs 0.3 kg/day, respectively; p<0.001). Crude protein intake, neutral detergent fibre intake and water consumption did not differ between treatments. Time spent eating was longer in FCH than in TMR (p=0.001), whereas time spent ruminating and total chewing time were longer (p<0.01) in TMR than in FCH. The number of displacements resulting from competition for feed in the main feeder in TMR treatment tended to be greater than in FCH treatment. There were no differences in the carcass characteristics and quality of meat of animals assigned to the different feeding methods, but the percentage of 18:2 n-6 was higher in FCH treatment. In summary, these results suggest that the use of TMR as a feeding method in beef cattle fed high concentrate diets did not affect performance and increased time spent ruminating with a potential decrease of ruminal acidosis incidence.
... However, no significant feed selection (Mazzenga et al., 2009) has been reported in individually fed beef cattle with different inclusion level of maize silage (20 to 40%). Also, individually fed beef calves showed variable preferences for energy-and protein-rich feed (Atwood et al., 2001). Under competitive feeding conditions such as in feedlots, beef cattle showed preference for longer and more structured (Cozzi and Gottardo, 2005) roughage feed components. ...
... Percentage of total eating duration time by hour across 24 h for cattle that did not eat within 1 h of feed offer ( G 0 ); cattle eating within 1 h of feed offer for 1 day ( G 1 ); for 2 days ( G 2 ); for 3 days ( G 3 ) and for all 4 days ( G 4 ) during days 3 to 6 on feed. our study, feedlot beef cattle may preferentially select differing components of mixed rations due to the composition of the available diet, physiological demand, limited bunk space and potentially also due to the previous diet that cattle were offered and post-ingestive feedback mechanisms (Launchbaugh et al., 1997;Atwood et al., 2001;Miller-Cushon and DeVries, 2017). Selective feeding behaviour is likely due to the combined effect of a roughage-based backgrounding diet that is typically offered before entry to feedlot and the short duration of transition to the new diet. ...
Article
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The timing of eating, relative to when feed is offered, is affected by the social rank of feedlot cattle due to limited feed bunk space. As cattle can select feed based on dietary preference, the timing of eating for cattle in feedlot may be associated with the ingested diet composition. Our objectives were to determine the nutritive value and timing of feed ingested by 100 feedlot cattle during transition and the association of timing of eating with feeding behaviours and average daily gain (ADG). Cattle behaviour and timing of eating were determined on 100 feedlot cattle using accelerometer-based ear tag sensors from days 3 to 6 post feedlot induction (observation period), and the ongoing impact of this period on ADG was determined for the full feed period (75 days). To determine eating patterns at the time of feed offer, cattle were grouped according to the number of days they were recorded as eating within 1 h of feed being offered across 4 observation days, G0: not present across 4 days, G1: present for 1 day, G2: 2 days, G3: 3 days and G4: present for each of the 4 days. Total mixed ration (TMR) samples were collected for nutritive value analysis from four locations along the feed bunk from the time feed was offered and at hourly intervals thereafter for 7 h each day during the observation period. The composition of feed in the bunk changed across the 7 h of measurement (P
... Preference assessments have been categorized according to their methodology, and include single-stimulus (SS), pairedstimulus (PS) and multiple-stimulus (MS). Even though not characterized as such, the methods used in the applied animal behavior literature are quite similar (Araujo and Milgram, 2004; Atwood et al., 2001; Clay et al., 2009; Shyan et al., 2002). For example, the one-pan assessment (Rashotte et al., 1984) seems to be a variation of the SS assessment. ...
... Preference assessments have been categorized according to their methodology, and include single-stimulus (SS), pairedstimulus (PS) and multiple-stimulus (MS). Even though not characterized as such, the methods used in the applied animal behavior literature are quite similar ( Araujo and Milgram, 2004;Atwood et al., 2001;Clay et al., 2009;Shyan et al., 2002). For example, the one-pan assessment ( ) seems to be a variation of the SS assessment. ...
... Improved performance (i.e., ADG) with reduced CV has been reported by several studies (Allison, 1985;Galyean et al., 1992;Horn et al., 2005;Williams et al., 2018), which allow us to suggest that the greater ADG of DIV and VAR could have been due to more consistent feed consumption as well as differences in the primary composition of diets, compared with the SFA. Further, choice of diet components as available to the DIV and VAR treatments has been shown to allow animals to better fulfil their nutrient requirements, thereby increasing the feed conversion efficiency of the consumed herbage (Atwood et al., 2001). For example, Atwood et al. (2001) offered calves free-choice from a diet components comprising a total mixed ration (TMR) or TMR and found that on average both treatments consumed a diet of similar energy to protein ratios; however, Means in a row without similar superscripts differ between treatments at each time (P ≤ 0.05). ...
... Further, choice of diet components as available to the DIV and VAR treatments has been shown to allow animals to better fulfil their nutrient requirements, thereby increasing the feed conversion efficiency of the consumed herbage (Atwood et al., 2001). For example, Atwood et al. (2001) offered calves free-choice from a diet components comprising a total mixed ration (TMR) or TMR and found that on average both treatments consumed a diet of similar energy to protein ratios; however, Means in a row without similar superscripts differ between treatments at each time (P ≤ 0.05). Morning (0700 to 1200 h on day 9 and 0734 to 1200 h on day 20); Afternoon (1200 to 2010 h on day 9 and 1200 to 1942 h on day 20). ...
Article
Intensive pastoral systems have moved away from diverse and varied diets towards overly simple monotonous diets. Feed choice through time is an obsolete way of providing forage to animals, as intensive management schemes generally allocate a single herbage or a dyad mixed sward. Monotonous feeding regimes impose nutritional repetition, which may impair animal performance and welfare. The objective of this experiment was to determine the impact of a diverse diet [DIV; free choice from perennial ryegrass (Lolium perenne L.), plantain (Plantago lanceolata L.), alfalfa (Medicago sativa L.), and chicory (Cichorium intybus L.) at all times], a varied diet [VAR; choice from ryegrass and plantain in the AM (0700-1600 h), and chicory and alfalfa in PM (1600-0700 h)], and a single forage diet of alfalfa [SFA; alfalfa at all times], on DMI, performance, and welfare of lambs. Six-month-old Coopworth ram lambs (n=21) were offered their respective fresh-forage treatment (n = 7) diet indoors for 20 days. The DIV lambs consumed 1.64 ± 0.03 kg DM/d (mean ± SEm), which was 6% more (P < 0.05; 1.54 ± 0.03 kg DM/d) than the SFA and were not different (P > 0.05; 1.59 ± 0.03 kg DM/d) to the VAR lambs. Average daily gain (ADG) of DIV (296 g/d) and VAR (378 g/d) was 30 and 67 % greater (P < 0.05) compared with the SFA lambs (227 g/d), respectively. The VAR lambs had 28% greater (P < 0.05) ADG than the DIV lambs. Differences among treatments were detected (P < 0.05) for the proportion of the day spent conducting the following behaviors: eating, ruminating, idling, lying, and standing. In addition, the number of bouts of stereotypic behaviors recorded from the SFA lambs (13.2 ± 2.2) was 150% greater (P < 0.05) than the DIV (5.1 ± 1.0) and VAR (5.5 ± 1.0) lambs. Our results suggest that the varied diet offered can improve animal performance and welfare compared to a monotonous SFA diet. Feeding management to provide a varied diet can improve performance relative to giving lambs free choice from taxonomically diverse forage options. Moreover, performance is affected by more than the primary chemical composition of the diet consumed, but how the diet is presented through time and the herbage species and quantities of each that are consumed to reach that chemical composition.
... Keywords: beef cattle, growth traits, carcass traits, meat quality, tannin Atwood et al. (2001), estudaram o efeito de diferentes formas de fornecimento da ração (volumoso e concentrado fornecidos de forma conjunta ou separada). Da mesma forma, La Manna et al. (2012) estudaram o efeito de diferentes formas de fornecimento da ração sobre o desempenho e a qualidade da carne de novilhos cruzados em fase de terminação e não verificaram efeito da forma e oferecimento do volumoso sobre o ganho de peso e características da carne. ...
... Para o ganho de peso médio diário, houve interação entre o tipo de sorgo e forma de fornecimento da ração, sendo que, os animais que receberam silagem de grão de sorgo de baixo teor de tanino com volumoso separado apresentaram maior ganho de peso médio diário (P=0,003) em comparação aos animais alimentados com o mesmo tipo de silagem de grão de sorgo, mas com o volumoso misturado (Tabela 4). Em trabalhos que utilizaram diferentes formas de fornecimento de ração, como as utilizadas no presente estudo, não foram observadas diferenças sobre o ganho de peso médio diário (ATWOOD et al., 2001; COLLARES et al., 2008; La MANNA et al., 2012). De acordo com McSweeney et al. (2001), o tanino pode reduzir a digestão da fibra, podendo diminuir o consumo de matéria seca. ...
Article
This work aimed to evaluate three varieties of sorghum as wet grain silage (high, low and white tannin), combined with two form of food supply (concentrated with roughage separated or mixed) on dry matter intake, body weight evolution, average daily growth, feed conversion, main meat and carcass traits (rib eye area, fat thickness and marbling in vivo and post mortem) in Hereford-Angus crossbred steers. Forty eight males castrated with 20 months of age were used, divided into randomized blocks, arranged in a 3 × 2 factorial. The regression coefficients for the weight gain of each treatment was compared using orthogonal contrasts. Dry matter intake was affected by the type of sorghum (P=0.002) and the form of food supply (P=0.0005). The form of food supply can interfere with the dry matter intake (P=0.0001) and weight (P=0.0001). Feed conversion and marbling, was affected by the type of sorghum (P=0.04). Meat marbling measured at deboning was affected by the form of food supply (P=0.04). The type of sorghum and form of food supply did not influence carcass characteristics and weights of meat cuts. The concentrated with roughage separated supply is nutritionally and operationally preferable.
... Differences among individuals in food preferences depend on variation in form and function, and marked differences are common even among "uniform" groups of animals in needs for nutrients (Scott and Provenza 1999) and abilities to cope with secondary compounds . Thus, variation among individuals can affect productivity of the group if the diet diverges much from what individuals at the extremes ----which can be as much as half of the group ----prefer and can tolerate (Provenza 1996;Scott and Provenza 1999;Atwood et al. 2001b). Herders continually provide the flock with a variety of foods that generates possibilities for each individual to eat combinations of foods that create synergies and thus enhance intake. ...
Article
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Landscapes are complex creative systems that continually transform due to ever-changing relationships among environments and organisms including human beings. During the past half-century, those who study these relationships and those who manage them have become increasingly isolated from one another in their attempts to understand and manage landscapes. As we have come to rely on experimental science to understand principles, we have diminished the importance of experiential knowledge in understanding and implementing practices. In this paper, we discuss convergence of the knowledge of herders from Southeastern France with the science of foraging behavior. We review insights of researchers gained through interviews with herders, surveys, and in situ recordings of the foraging behavior of closely herded sheep and goats. Though years of hands-on experience, herders have come to understand processes involved in food and habitat selection. Using a conceptual model of four steps, which represent four intertwined processes for a given herder-herd-fodder resource, we describe how herders 1) teach their animals to use the full range of forages, 2) train the herd to respect the boundaries of grazing areas, 3) modulate what they call the “temporary palatability scoring” of forages, and 4) establish daily grazing circuits to stimulate appetite and intake through meal sequencing. This knowledge is also valuable when the objective is to boost appetite for particular forages, such as coarse grasses, scrub, and invasive species. The practices of herders are consistent with scientific studies that show the importance of plant biodiversity for enabling animals to select nutritious diets and the significance of animal learning and culture on nutrition, production, and health. We conclude by highlighting implications for furthering the exchange between herders and scientists and by providing implications for managing grazing on pastures and rangelands, with or without shepherds and dogs, and targeting grazing on particular plants and habitats.
... As in the present study, a positive effect of TMR feeding on DMI was noted previously in finishing steers (Caplis et al. 2005, Keane et al. 2006, finishing heifers (Cooke et al. 2004), fattening calves (Atwood et al. 2001) and in a meta-analysis based on a dataset of feeding experiments in growing cattle . Earlier, Petchey and Broadbent (1980) compared separate or mixed feeding of silage and concentrates for finishing Friesian steers at silage:concentrate rations ranging from 0 to 1.0. ...
Article
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A randomised complete block design was used to study the effects on animal performance of (1) the increasing level of supplementary concentrate with grass silage (GS), and (2) feeding GS and concentrates separately or as a total mixed ration (TMR). A feeding experiment comprised 32 dairy bulls with average initial live weight of 145 kg. The feeding treatments were: (1) GS (660 g kg-1 dry matter intake) plus medium level of rolled barley (330) offered separately, (2) GS (660) plus medium level of rolled barley (330) offered as TMR, (3) GS (330) plus high level of rolled barley (660) offered separately, and (4) GS (330) plus high level of rolled barley (660) offered as TMR. During the experiment (398 days) the bulls were fed ad libitum either GS or TMR. The increasing concentrate level increased energy intake, carcass gain and dressing proportion of the bulls but had no effects on carcass conformation or fat score. TMR feeding had no effects on carcass gain, dressing proportion, carcass conformation or fat score but increased dry matter and energy intake compared to the separate feeding.
... For instance, in Exp. 1 A. leucoclada was consumed in a range from 160 to 395 g DM/d, and similar variations were found in Exp. 2 for feed intake of B. pendula. Such variability in individual feed intake was also found by Atwood et al. (2001) under choice feeding conditions and could be an expression of the different nutritional requirements of the individual animals (Kyriazakis and Oldham, 1993). Despite similarities among the animals in terms of breed, age, BW, and performance, they might have differed in morphology and physiology (Provenza et al., 2007). ...
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A satisfactory intake of novel low-quality forages by ruminants may require previous experience with this feed. Therefore, this study tested in sheep whether experience with forages from woody plants had an influence on feed intake, feeding behavior, and nutrient supply when offered in a multiple-choice arrangement. Two sheep experiments were conducted, 1 in Syria (Mediterranean region; Exp. 1) and the other in Switzerland (Central Europe; Exp. 2), that investigated 5 and 6 woody test plants, respectively. In Exp. 1, the test plants were Artemisia herba-alba, Atriplex leucoclada, Haloxylon articulatum, Noaea mucronata, and Salsola vermiculata. In Exp. 2, Betula pendula, Castanea sativa, and Juglans regia were used in addition to A. leucoclada, H. articulatum, and S. vermiculata (the plants most consumed in Exp. 1). In each experiment, 12 lactating sheep (Awassi sheep in Exp. 1 and East Friesian Milk sheep in Exp. 2) were allocated to 2 groups ("experienced" and "naïve"). Experienced sheep subsequently were familiarized with each test plant during a learning period of binary choices (1 test plant vs. barley straw) for 4 h in the morning for 7 d each. The naïve group received only straw. During the rest of the day, a basal diet composed of barley straw (ad libitum) and concentrate was offered to both groups. For the 2 wk following the learning period, the sheep were subjected to feeding of the basal diet to avoid carryover effects of the last offered test plant. In the following multiple-choice period, both groups were allowed to select from all test plants during 4 h in the morning for 14 d. Forage intake after 4 and 24 h and feeding behavior during the first 30 min of the test feeding were assessed. Milk yield and composition were measured at the end of the multiple-choice period. Nutrient intake was calculated using feed intake measurements and compositional analyses. Only in Exp. 2, group differences (P < 0.05) were found on d 1 of the multiple-choice period. The experienced sheep consumed more total forage, straw, OM, NDF, ADF, and ADL (nutrients without concentrate). However, across the entire multiple-choice period, there were no differences (P ≥ 0.05) in forage and nutrient intake, feeding behavior, and milk yield and composition between the groups in both experiments. This suggests that sheep can quickly adapt to previously unknown woody feeds of varying origin and quality offered as dried supplements.
... This could be as a result of better palatability due to high proportion of concentrate in the diet. Differences in DMI could also be partially attributed to the ratio of protein to energy ingested with offering of mixed diets compared with separate access to dietary ingredients (Atwood et al., 2001; Fedele et al., 2002). This observation is in agreement with McLeod and Baldwin (2000) who observed a similar higher dry matter intake when lambs were fed diet consisting of forage and concentrate at ratio 30:70. ...
... Studies with herbivores also illustrate the uniqueness of individuals Scott & Provenza, 1999). For instance, in a two-month study, no two individuals ever selected the same combination of foods from day to day when calves could choose among four foods e rolled barley, rolled corn, corn silage, and alfalfa hay (Atwood, Provenza, Wiedmeier, & Banner, 2001a). The average ratio of protein to energy ingested throughout the study was identical to that for a 'total-mixed-ration' e made by grinding and mixing the four foods in proportions formulated to meet the nutritional needs of the 'average' individual e balanced nutritionally to maximize growth at least cost. ...
Article
We contend that palates link herbivores and humans with landscapes and consider how these relationships have changed historically. An attuned palate, which enables herbivores to meet needs for nutrients and self-medicate to rectify maladies, evolves from three interrelated processes: flavor-feedback associations, availability of phytochemically rich foods, and learning in utero and early in life to eat nourishing combinations of foods. That occurs when wild or domestic herbivores forage on phytochemically rich landscapes, is less common when domestic herbivores forage on monoculture pastures, is close to zero for herbivores in feedlots, and is increasingly rare for people who forage in modern food outlets. Unlike our ancestors, the palates of many individuals are no longer linked in healthy ways with landscapes. Industrial farming and selection for yield, appearance, and transportability diminished the flavor, phytochemical richness, and nutritive value of fruits and vegetables for humans. Phytochemically impoverished pastures and feedlot diets can adversely affect the health of livestock and the flavor and nutritive value of meat and milk products for humans. While flavors of produce, meat, and dairy have become blander, processed foods have become more desirable as people have learned to link synthetic flavors with feedback from energy-rich compounds that obscure nutritional sameness and diminish health. Thus, the roles plants and animals once played in nutrition have been usurped by processed foods that are altered, fortified, and enriched in ways that can adversely affect appetitive states and food preferences. The need to amend foods, and to take nutrient supplements, could be reduced by creating phytochemically rich plants and herbivores and by creating cultures that know how to combine foods into meals that nourish and satiate. Copyright © 2015. Published by Elsevier Ltd.
... Differences among individuals in food preferences depend on variation in form and function, and marked differences are common even among " uniform " groups of animals in needs for nutrients (Scott and Provenza, 1999) and abilities to cope with secondary compounds (Provenza et al., 1992Provenza et al., , 1999). Thus variation among individuals can affect productivity of the group if the diet diverges much from what individuals at the extremes—which can be as much as half of the group—prefer and can tolerate (Provenza, 1996; Scott and Provenza, 1999; Atwood et al., 2001b). Herders continually provide the flock with a variety of foods that generates possibilities for each individual to eat combinations of foods that create synergies and thus enhance intake. ...
Book
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Far from a nostalgic glimpse into a romanticized lifestyle, this book teaches how this sophisticated art and set of tangible skills has application in modern, North American range/livestock management. Through academic study and analysis and in-depth interviews with master shepherds readers will be amazed by the deep connection between the nutritional need for animals to feed, the powers of observation used by the shepherds to effectively care for and manage large herds, and how the traditional moving of the animals is more fitting to many landscapes than even the most progressive rotational grazing and moveable fencing systems.
... Differences in the composition and formulation of the monotonous diet (which commonly represents the control treatment in free-choice feeding experiments) may help to explain differences in total intake between studies. For instance, total intake of calves exposed to a choice of foods was observed to be higher (Boga et al., 2009), lower (Atwood et al., 2001), or similar (Montoro and Bach, 2012) than in calves exposed to a monotonous diet. ...
Article
Farm animals are commonly restricted to a reduced array of foods, like total mixed rations or pastures with low species diversity. Under these conditions, animals are less likely to satisfy their specific and changing nutrient requirements. In addition, foods and flavors eaten too frequently or in excess induce sensory-specific satiety and can cause aversions. Thus, sensory and postingestive monotony may reduce animal welfare. We hypothesized that exposure to monotonous diets, even if they are considered to be nutritionally balanced, is stressful for sheep. Twenty-four 2-month-old male Corriedale lambs were randomly assigned to two experimental groups. One group (diversity treatment, DIV) received a free choice of four-way combinations of two foods with low and two foods with high protein/energy ratios from an array of seven foods (three foods high in protein/energy ratio: soybean meal, sunflower meal, and alfalfa pellets, and four foods low in protein/energy ratio: barley grain, oat grain, milo grain, and corn grain). The other group (monotony treatment, MON) was fed a balanced ration containing all foods offered to lambs in DIV. Foods were offered in four individual buckets and exposure lasted 55 days. During exposure, feeding behavior was assessed, and blood samples were taken for a complete blood cell count and to determine serum cortisol concentration. Lambs in MON showed greater cortisol levels (31.44 vs. 19.90 ± 3.30 nmol/L [means ± SEM]; P = 0.025) and a greater neutrophil to lymphocyte ratio (0.37 vs. 0.26 ± 0.05; P = 0.044) than lambs in DIV. Lambs in DIV spent a lower proportion of time eating (0.38 vs. 0.49 ± 0.02; P < 0.001) and showed a greater intake rate (17.73 vs. 14.09 ± 1.26 g/min, P < 0.044) than lambs in MON. They also showed a greater proportion of time lying (0.44 vs. 0.36 ± 0.03; P = 0.049) and greater activity (0.047 vs. 0.035 ± 0.003; P = 0.003) than lambs in MON. However, final body weight and the average daily weight gain were not affected by treatment (P > 0.05). Our results showed that restricting lambs’ dietary breadth produced changes in blood and behavioral parameters previously shown to be indicative of stress in sheep. The importance of incorporating food choice as an alternative practice to overcome stress associated to the traditional livestock feeding management is discussed.
... In another study, palatability was not consistently affected by whey up to 15% in the concentrate for calves (Morrill and Dayton, 1974). Comparing the intake and performance of beef calves offered a mixed ration (no choice among foods) or the ingredients offered separately (choice) showed that animals tended to eat more of the total-mixed ration (Atwood et al., 2001). Animals in the two treatments also ate different amounts on different days, which resulted in a treatment  day interaction. ...
Article
A palatable concentrate may stimulate intake and ease weaning stress. This study investigated the effect of the incorporation of spelt in the concentrate on calf performance (Experiment 1) and the palatability (Experiment 2).Sixty-six newborn Belgian Blue double-muscled female calves were involved in Experiment 1 to investigate the effect of incorporating 30% spelt grain in the concentrate (S+) as a replacement for 15% barley and 15% wheat (S−) during a 143-day rearing period. Calves received reconstituted milk at 10% of their birth weight. They were weaned when concentrate intake achieved 0.75 kg/day. Grass hay was fed ad lib. After the rearing period all calves were adapted during 2 weeks to the same diet, fed to appetite, and consisting of maize silage and concentrate without spelt. Performances were investigated during 4 weeks. Spelt reduced the in vitro organic matter digestibility and the net energy content of the concentrate from 91.5% and 7.4 MJ/kg to 88.1% and 7.0 MJ/kg, respectively. It stimulated concentrate intake initially, so that calves were weaned after 58 days compared to 67 days for calves fed S− concentrate (P=0.012). A higher amount of dry matter (P=0.056) was required per kg live-weight gain for S+ concentrate, but energy efficiency was similar for both treatments (P=0.415). Daily live-weight gain for the entire rearing period was not affected (P=0.970) and averaged 0.77 kg. Daily live-weight gain and feed intake were lower for the S+ treatment during the transition period (P<0.001), but neither age at 1st calving nor post-partum live-weight was affected.Five Holstein-Friesian females and five Belgian Blue double-muscled females, aging 203±8 (mean±standard error) days initially, and unaccustomed to eating S− and S+ concentrates, were involved in a preference test (Experiment 2). Both concentrates were administered free choice. Grass hay was fed ad lib. Concentrate intake was registered during 4 consecutive days at 0.5, 1, 3, 5, 8 and 24 h after the morning feeding. Concentrate containing spelt was preferred by Holstein-Friesian calves but not by Belgian Blue calves, resulting in a concentrate×breed interaction. This interaction emphasised the complex role of sensory and metabolic signals in the control of feed intake.It was concluded that spelt can stimulate concentrate intake, so that rearing calves can be weaned earlier. However, the preference of concentrate containing spelt exerted no major effect on animal performance during the entire rearing period.
... Nonsupplemented cattle took more bites of forbs than supplemented animals, and this pattern could be explained by the fact that protein supplementation reduced the need for selection of forbs, a forage source with greater CP content than medusahead and other annual grasses. Cattle are able to balance the ratio of energy to protein in their diet (Atwood et al., 2001) as they typically select a diet that meets nutrient requirements (Weir and Torell, 1959;Coleman and Barth, 1973) while avoiding an excessive supply of rumen degradable protein from their diet (Tolkamp et al., 1998). Foraging cattle (Odadi et al., 2013) have been reported to trade off protein-rich forbs for protein-poor grasses when supplemented with protein and the opposite pattern was observed in sheep supplemented with an energy concentrate (J. ...
Article
Medusahead [ (L.) Nevski] has become a major invasive plant on the annual grass-dominated rangelands within the Channeled Scablands of eastern Washington. Livestock typically avoid grazing medusahead, and forage alternatives are becoming limited in the region. Our hypothesis was that supplying a high-CP supplement would provide a nutritional context that complements the nutritional composition of medusahead and other annual grasses and thus aid cattle in utilizing this vegetation component, making grazing a more effective method of weed control. Cattle grazed annual grass-infested rangelands dominated with medusahead for 10-d periods during June, July, and August over 2 consecutive years. Eight separate pastures were grazed by cattle pairs during each of the 3 grazing periods. Cattle in 4 control pastures received no supplement and cattle in another 4 pastures received a supplement of canola meal that supplied 75% of the daily recommended CP requirement. Bite counts were used to determine diet composition. Forage categories consisted of annual grasses, perennial grasses, and forbs. Bites taken of annual grasses were similar between treatment groups during the first 5 d of the grazing period ( > 0.05), and then cattle supplemented with canola meal increased consumption of annual grasses, during d 6 to 10 of the grazing periods, over nonsupplemented animals ( < 0.05). Consumption of annual grasses was greater during the second year of the grazing study ( < 0.05), likely due to a decline in abundance of forage alternatives in the plant community. The percentage of medusahead in the annual grass forage class tended to decrease in grazed pastures over the 3 yr of the study ( = 0.056): 87 ± 4.2, 64 ± 3.6, and 50 ± 3.6%, respectively. The percentage of medusahead in the annual grasses was similar across years in nongrazed pastures ( > 0.05). Forb production was greatest the first year of grazing and declined the second year of grazing and continued to decline the following year with no grazing ( < 0.05). Perennial grass production was low throughout the study. The effects of grazing on medusahead abundance suggest cattle may be used to graze this weed after it has matured in an integrated management program with other forms of control to reduce infestation prior to seeding with desirable forage species.
... Some surprising work (Provenza et al 1996. Scott and Provenza 1999, Atwood et al 2001 indicates that there is great diversity among individual animals and among individual plants-even those that are closely related. As much as half of a herd or flock can be considered "outliers," outside the norm in their nutritional needs and tolerances (Provenza et al 2002). ...
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Intensive Silvopasture Systems (ISS) – integrating livestock, trees, pasture, and woody browse in sustainable ecosystems – are being widely implemented in Colombia. They have been found to provide multiple benefits, including 3-5 times as much milk and meat production per animal, up to ten times higher stocking rates per hectare, and nine times higher carbon sequestration rates per hectare than conventional agricultural methods. ISS has not yet been implemented outside of the tropics, but if an analog ISS system could be developed using species native to temperate climates, the hope is that similar benefits in production and carbon sequestration might be reaped. This paper will highlight a variety of practices from around the world that might be combined to create an effective temperate-region ISS system. These practices include: ISS in Colombia, use of black locust as a browse species, the MENU method of herding in France, browse diversity research, the historic practice of pollarding in Europe, and Hi-sAFe, an agroforestry computer model that may be useful for designing effective ISS systems.
... Access to a variety of feeds and making choices about which food to eat may allow an animal to regulate individual dietary needs [103][104][105]. For example, dairy calves housed indoors with free choice to different feeds showed individual variation in their dietary choices that led to few non-nutritive oral behaviours [105], while still meeting their nutritional needs [106]. The next step may be to describe the agency a calf may exercise over what he or she eats when provided access to pasture. ...
Article
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One important type of animal welfare concern is “natural living” (i.e., that animals are able to express natural behaviours that are important to them, and to engage with aspects of the natural world that they find important). The aims of this narrative review were to describe the behavioural development of calves (Bos taurus) in natural settings and use this to identify characteristics of natural systems that may be important to consider relative to this natural living conception of animal welfare. At birth, calves are licked by their mothers and soon stand to suckle for colostrum, and during the milk-feeding period, calves spend much of their time lying down. In natural systems, calves perform a variety of social behaviours with herd-mates, and slowly transition from their mother’s milk to eating solid food, by gradually increasing time spent grazing and ruminating. In contrast, on most commercial dairy systems, dairy calves are removed from their mothers at birth, housed individually, fed restricted amounts of milk and weaned abruptly at a young age. The results of this review suggest that accommodating key natural behaviours, for example through the use of teat feeding of milk, social housing, and gradual weaning, can help address welfare concerns.
... postingestive feedbacks) and their nutritional requirements in order to construct their daily meals (Favreau-Peigné et al., 2013). This explains why even young ruminants with dietary experience construct highly variable diets on a day-to-day basis, when dietary choice is provided (Atwood et al., 2001). Simitzis et al. (2008) demonstrated that early life experience with oregano essential oil increased lambs' preference for oregano essential oil containing diets later in life. ...
Article
The objective of this experiment was to determine how early life exposure to plant extracts would influence grazing behavior and dietary preference. This experiment used ram lambs (n = 60; initial body weight = 41.8 ± 3.8 kg, mean ± standard deviation). Their dams were either provided no plant extract (CON), a seaweed (Ecklonia radiata) extract (10 mL/ram/d; SWE), or an extract of seaweed, chicory (Cichorium intybus), plantain (Plantago lanceolata), lucerne (Medicago sativa), and dock (Rumex obtusifolius; 10 mL/ram/d; SWP). Treatments were provided to the dams starting in late gestation (63.9 ± 6.5 d before lambing), through to weaning of the lambs. After weaning (94 ± 6.5 d old), lambs received the respective treatments of their dams until the initiation of the current experiment (66 d after weaning). At the initiation of the current experiment, the lambs were placed into a paddock containing spatially separated strips of ryegrass (Lolium perenne), chicory, plantain, lucerne, and dock, of which they received a fresh break, weekly. During week 1, SWP had more (P < 0.05) scans spent grazing than SWE and CON. Also, during week 1, SWP had a greater (P < 0.05) number of grazing bouts and a shorter (P < 0.05) grazing bout duration compared with SWE and CON. In week 1, SWP had 78.6% and 167.3% more (P < 0.05) proportion of grazing scans spent in chicory than CON and SWE, respectively. Concomitantly, SWP had 33.5% and 59.7% less (P < 0.05) grazing scans in ryegrass than CON and SWE, respectively. At the observation weeks 4 and 7, the grazing behavior and dietary preference between treatments was reduced, indicating learning occurred by CON and SWE. Overall, these results indicate that early life exposure to a plant extract alters dietary preference to the species contained in that extract and also changes grazing behavior, which suggests that the extract provided familiarity to the plants and thereby reduced dietary neophobia.
... Calves are moved from familiar (mother, peers, home pastures) to unfamiliar (feedlots) haunts, which causes fear and distress. Though individuals differ in preferences due to experiences in utero and early in life (Atwood et al., 2001;Wiedmeier et al., 2012;Beck, 2020), they have no chance to selfselect their own diets, which violates their freedom to express normal behavior, maintain health, and avert disease. Like us, they dislike any food eaten too often or in excess, which causes stress and food aversions (Catanese et al., 2013). ...
Article
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Humans are participating in the sixth mass extinction, and for the first time in 200,000 years, our species may be on the brink of extinction. We are facing the greatest challenges we have ever encountered, namely how to nourish eight billion people in the face of changing climates ecologically, diminish disparity between the haves and the have-nots economically, and ease xenophobia, fear, and hatred socially? Historically, our tribal nature served us well, but the costs of tribalism are now far too great for one people inhabiting one tiny orb. If we hope to survive, we must mend the divides that isolate us from one another and the communities we inhabit. While not doing so could be our undoing, doing so could transform our collective consciousness into one that respects, nourishes, and embraces our interdependence with life on Earth. At a basic level, we can cultivate life by using nature as a model for how to produce and consume food; by decreasing our dependence on fossil fuels for energy to grow, process, and transport food; and by transcending persistent battles over one-size-fits-all plant- or animal-based diets. If we learn to do so in ways that nourish life, we may awaken individually and collectively to the wisdom of the Maori proverb Ko au te whenua. Ko te whenua Ko au: I am the land. The land is me. In this paper, we use “scapes” —foodscapes, landscapes, heartscapes, and thoughtscapes—as unifying themes to discuss our linkages with communities. We begin by considering how palates link animals with foodscapes. Next, we address how palates link foodscapes with landscapes. We then consider how, through our reverence for life, heartscapes link palates with foodscapes and landscapes. We conclude with transformations of thoughtscapes needed to appreciate life on Earth as a community to which we belong, rather than as a commodity that belongs to us.
... Strategic supplementation of livestock on pasture with industrial by-products, inedible to humans (Sunvold et al., 1991;Macdonald et al., 2007), also has potential to increase the carrying capacity of pasture-based grazing systems and mitigate potential welfare issues associated with feedlots, such as reduced ability to express natural behavior and self-selection of diets (Atwood et al., 2001;Villalba and Manteca, 2019). For example, feeding limited amounts of phytochemically-rich fruit and vegetable by-products such as leaves, pomace, peels, rinds, pulp, seeds, and stems (Sruamsiri, 2007;Wadhwa and Bakshi, 2013;Salami et al., 2019) to livestock on pasture can potentially mitigate some nutritional deficits, decrease environmental impacts, and reduce the of risk of overgrazing and land unavailability, while enhancing the phytochemical richness of meat and milk (Provenza et al., 2003(Provenza et al., , 2019Salami et al., 2019). ...
Article
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While commission reports and nutritional guidelines raise concerns about the effects of consuming red meat on human health, the impacts of how livestock are raised and finished on consumer health are generally ignored. Meat and milk, irrespective of rearing practices, provide many essential nutrients including bioavailable protein, zinc, iron, selenium, calcium, and/or B12. Emerging data indicate that when livestock are eating a diverse array of plants on pasture, additional health-promoting phytonutrients—terpenoids, phenols, carotenoids, and anti-oxidants—become concentrated in their meat and milk. Several phytochemicals found in grass-fed meat and milk are in quantities comparable to those found in plant foods known to have anti-inflammatory, anti-carcinogenic, and cardioprotective effects. As meat and milk are often not considered as sources of phytochemicals, their presence has remained largely underappreciated in discussions of nutritional differences between feedlot-fed (grain-fed) and pasture-finished (grass-fed) meat and dairy, which have predominantly centered around the ω-3 fatty acids and conjugated linoleic acid. Grazing livestock on plant-species diverse pastures concentrates a wider variety and higher amounts of phytochemicals in meat and milk compared to grazing monoculture pastures, while phytochemicals are further reduced or absent in meat and milk of grain-fed animals. The co-evolution of plants and herbivores has led to plants/crops being more productive when grazed in accordance with agroecological principles. The increased phytochemical richness of productive vegetation has potential to improve the health of animals and upscale these nutrients to also benefit human health. Several studies have found increased anti-oxidant activity in meat and milk of grass-fed vs. grain-fed animals. Only a handful of studies have investigated the effects of grass-fed meat and dairy consumption on human health and show potential for anti-inflammatory effects and improved lipoprotein profiles. However, current knowledge does not allow for direct linking of livestock production practices to human health. Future research should systematically assess linkages between the phytochemical richness of livestock diets, the nutrient density of animal foods, and subsequent effects on human metabolic health. This is important given current societal concerns about red meat consumption and human health. Addressing this research gap will require greater collaborative efforts from the fields of agriculture and medicine.
... Offering by-products on pasture, as opposed to feeding them to cattle in feedlots, would also mitigate some of the animal welfare issues associated with feedlots such as unfamiliar environments, inability to self-select their diet, and the ability to express natural behavior (Atwood et al., 2001;Villalba and Manteca, 2019). Offering by-products to cattle on pasture may represent a worthwhile opportunity for the livestock industry to improve consumer perception while maintaining the ability to upcycle by-products to meet customer demand. ...
Article
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There is wide scale concern about the effects of red meat on human health and climate change. Plant-based meat alternatives, designed to mimic the sensory experience and nutritional value of red meat, have recently been introduced into consumer markets. Plant-based meats are marketed under the premise of environmental and human health benefits and are aimed appeal to a broad consumer base. Meat production is critiqued for its overuse of water supplies, landscape degradation, and greenhouse gas emission, and depending on production practices, environmental footprints may be lower with plant-based meat alternatives. Life-cycle analyses suggest that the novel plant-based meat alternatives have an environmental footprint that may be lower than beef finished in feedlots, but higher than beef raised on well-managed pastures. In this review, we discuss the nutritional and ecological impacts of eating plant-based meat alternatives vs. animal meats. Most humans fall on a spectrum of omnivory: they satisfy some nutrient requirements better from plant foods, while needs for other nutrients are met more readily from animal foods. Animal foods also facilitate the uptake of several plant-derived nutrients (zinc and iron), while plant nutrients can offer protection against potentially harmful compounds in cooked meat. Thus, plant and animal foods operate in symbiotic ways to improve human health. The mimicking of animal foods using isolated plant proteins, fats, vitamins, and minerals likely underestimates the true nutritional complexity of whole foods in their natural state, which contain hundreds to thousands of nutrients that impact human health. Novel plant-based meat alternatives should arguably be treated as meat alternatives in terms of sensory experience, but not as true meat replacements in terms of nutrition. If consumers wish to replace some of their meat with plant-based alternatives in the diet (a “flexitarian approach”) this is unlikely to negatively impact their overall nutrient status, but this also depends on what other foods are in their diet and the life stage of the individual.
... Although it is known that weaned calves show large variation in feed preferences (Atwood et al., 2001), ...
Article
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The recent trend in the dairy industry toward ad libitum feeding of young calves merits reconsideration of calf milk replacer (CMR) formulations. Additionally, feed intake regulation in young calves provided with ad libitum milk and solid feeds is insufficiently understood. This study was designed to determine the effect of exchanging lactose for fat in CMR on voluntary feed intake and growth performance. Lactose was exchanged for fat on a weight/weight basis, resulting in different energy contents per kilogram of CMR. Thirty-two male calves (1.7 ± 0.12 d of age, 47.6 ± 0.83 kg of body weight) were assigned to 1 of 16 blocks based on arrival date. Within each block, calves were randomly assigned to 1 of 2 treatments. The experimental period was divided into 4 periods. In period 1, until 14 ± 1.7 d of age, calves were individually housed, restricted-fed their assigned CMR treatments at 2.5 to 3 L twice daily, and provided with unlimited access to water, chopped straw, and starter. In period 2, calves were group-housed with 8 calves per pen and received ad libitum access to their assigned CMR treatments, starter feed, chopped wheat straw, and water. During period 3, from 43 until 63 d of age, calves were weaned by restricting CMR allowance in 2 steps, maintaining access to all other feeds. All calves were completely weaned at d 64 of age and were monitored until 77 d of age (period 4). Measurements included the intake of all dietary components, body weight gain, and a selection of blood traits. Increasing fat content at the expense of lactose decreased CMR intake by 10%, whereas total calculated metabolizable energy intake and growth remained equal between treatments. Total solid feed (starter and straw) consumption was not affected by CMR composition. These data indicate that calves fed ad libitum regulate their CMR intake based on energy content. High-fat CMR increased plasma phosphate, nonesterified fatty acids, triglycerides, and bilirubin, whereas plasma glucose remained unchanged. Despite the limited animal numbers in the present experiment, there was a significant decrease in the total number of health events (mainly respiratory) requiring therapeutic intervention and in the total number of therapeutic interventions in calves fed high-fat CMR. Calves appeared to consume CMR based on energy content, with a difference in ad libitum intake proportional to the difference in energy content of the CMR, maintaining equal body weight gain and solid feed intake.
... Calves are moved from familiar (mother, peers, home pastures) to unfamiliar (feedlots) haunts, which causes fear and distress. Though individuals differ in preferences due to experiences in utero and early in life (Atwood et al., 2001;Wiedmeier et al., 2012;Beck, 2020), they have no chance to selfselect their own diets, which violates their freedom to express normal behavior, maintain health, and avert disease. Like us, they dislike any food eaten too often or in excess, which causes stress and food aversions (Catanese et al., 2013). ...
... Interpretation of grazing preference in this study could be summated by the influence of forage quality, relative abundance, and prior grazing experiences. Grazing animals select for forages that meet their dietary needs particularly when balancing their energy to protein needs (Atwood et al., 2001). For instance, cattle supplemented with protein-rich feeds increased their selection of high-fiber grasses (Odadi et al., 2013), ...
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Medusahead (Taeniatherum caput-medusae (L.) Nevski) is currently one of the biggest threats to rangelands and livestock operations in the Western US. High silica concentrations in medusahead contribute to its invasiveness. I developed a model to explain how silica is involved in the invasion process, and attempted to manipulate silica to increase use of the grass by livestock. Experiments were conducted to determine: 1) whether rotational grazing on established forages of improved nutritional quality would provide supplemental nutrients to increase cattle use of medusahead; 2) evaluate intake of and preference for medusahead treated with a glyphosate herbicide at different rates by sheep; and 3) evaluate intake and selection of medusahead by cattle by separating the effects of a glyphosate herbicide (Roundup®) from other chemicals in the formulation (salt, adjuvant). Additionally, experiments were conducted to 4) determine the nutritional value and digestibility of medusahead treated with Roundup® at different rates and at different plant particle sizes; and 5) determine if cattle grazing with trampling can increase seeding success on medusahead-invaded rangelands. Rotational grazing from supplemental pastures to medusahead-invaded pastures increased medusahead use by cattle during the second year of the study. Furthermore, glyphosate did not increase medusahead consumption in a choice between three glyphosate treatments, but did in a two-way choice test. Cattle grazed glyphosate-treated medusahead more than that of the non-treated grass and completely avoided the salt-treated grass. The active ingredient in a glyphosate herbicide increased consumption of medusahead while other ingredients in the herbicide (i.e., salt and adjuvant) had no influence on this choice. A smaller particle size increased the digestibility of medusahead compared to larger particle sizes. Glyphosate also increases digestibility, but not as much as particle size. Finally, cattle trampling did not help establish seeded plant species, and the seeding attempt was unsuccessful. Thus, grazing rotations between improved pastures and medusahead-infested rangeland, and the combined glyphosate application-grazing are new approaches for medusahead control, as they prepare a seed bed for revegetation and increase the nutritional quality of the grass for improved livestock nutrition.
... It may be argued that, if animals are given the possibility of choosing their diets, they may not necessarily eat what is best for them, and they may not consume a diet adequate to meet their nutritional requirements. Although we cannot exclude that this may happen in some cases, research by [67] showed that calves offered with a varied diet reached the same nutritional level provided by a standard balanced mixed ration, yet each animal ate a diet different from the other animals. Data supporting the evidence that ruminants are able to select a diet close to their needs and minimise the ingestion of anti-nutritional compounds when they are given the possibility to choose among different feeds are reviewed by [58]. ...
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Until now, most research has focused on the development of indicators of negative welfare, and relatively few studies provide information on valid, reliable, and feasible indicators addressing positive aspects of animal welfare. However, a lack of suffering does not guarantee that animals are experiencing a positive welfare state. The aim of the present review is to identify promising valid and reliable animal-based indicators for the assessment of positive welfare that might be included in welfare assessment protocols for ruminants, and to discuss them in the light of the five domains model, highlighting possible gaps to be filled by future research. Based on the existing literature in the main databases, each indicator was evaluated in terms of its validity, reliability, and on-farm feasibility. Some valid indicators were identified, but a lot of the validity evidence is based on their absence when a negative situation is present; furthermore, only a few indicators are available in the domains of Nutrition and Health. Reliability has been seldom addressed. On-farm feasibility could be increased by developing specific sampling strategies and/or relying on the use of video- or automatic-recording devices. In conclusion, several indicators are potentially available (e.g., synchronisation of lying and feeding, coat or fleece condition, qualitative behaviour assessment), but further research is required.
... Animals in feedlots are fed total-mixed rations high in grain with little chance to self-select their own diets, which violates their freedom to maintain individual health and vigor and produces changes in blood cortisol and behavioral parameters indicative of stress (42,43). Individuals vary markedly in their preferences for different foods due to past experiences and individuality in morphology and physiology, which differentially affects their abilities to tolerate excesses and deficits of nutrients in their diets (44,45). Animals acquire aversions to foods eaten too often or in excessive amounts (46,47), and large numbers of animals confined and fed only total-mixed rations high in grain experience stress and malaise (nausea) (48), which violates their freedom from discomfort. ...
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The health of livestock, humans, and environments is tied to plant diversity—and associated phytochemical richness—across landscapes. Health is enhanced when livestock forage on phytochemically rich landscapes, is reduced when livestock forage on simple mixture or monoculture pastures or consume high-grain rations in feedlots, and is greatly reduced for people who eat highly processed diets. Circumstantial evidence supports the hypothesis that phytochemical richness of herbivore diets enhances biochemical richness of meat and dairy, which is linked with human and environmental health. Among many roles they play in health, phytochemicals in herbivore diets protect meat and dairy from protein oxidation and lipid peroxidation that cause low-grade systemic inflammation implicated in heart disease and cancer in humans. Yet, epidemiological and ecological studies critical of red meat consumption do not discriminate among meats from livestock fed high-grain rations as opposed to livestock foraging on landscapes of increasing phytochemical richness. The global shift away from phytochemically and biochemically rich wholesome foods to highly processed diets enabled 2.1 billion people to become overweight or obese and increased the incidence of type II diabetes, heart disease, and cancer. Unimpeded, these trends will add to a projected substantial increase in greenhouse gas emissions (GHGE) from producing food and clearing land by 2050. While agriculture contributes one quarter of GHGE, livestock can play a sizable role in climate mitigation. Of 80 ways to alleviate climate change, regenerative agriculture—managed grazing, silvopasture, tree intercropping, conservation agriculture, and farmland restoration—jointly rank number one as ways to sequester GHG. Mitigating the impacts of people in the Anthropocene can be enabled through diet to improve human and environmental health, but that will require profound changes in society. People will have to learn we are members of nature's communities. What we do to them, we do to ourselves. Only by nurturing them can we nurture ourselves.
... The larger variation in concentrate intake during periods of concentrate changes compared with the periods with constant concentrate allowance may reflect differences in individual responses to the changes in concentrate allowance. Of note, a high individual variation in the motivation to perform feed-related exploratory behavior and the fear of novelty have been demonstrated in calves and heifers (Atwood et al., 2001;Meagher et al., 2017). ...
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The aim of this study was to investigate the short-term responses of dairy cows during periods of change in the concentrate allowance in an automatic milking system. The experiment had a design with a 2 × 2 factorial arrangement including 2 types of concentrates and 2 amounts of concentrates (type O: mix of pelleted concentrate and steamrolled, acidified barley; type S: pelleted) in amounts of 3 and 6 kg/d. The experiment length was 11 wk. The concentrate type changed between wk 6 and 7 and included both increase and decrease in concentrate allowance for each concentrate type. The concentrate allowance was changed by 0.5 kg/d over 6 d. The 96 cows (48 Danish Jersey, 48 Danish Holstein) included in the experiment were blocked according to breed, parity, and days in milk, and randomly divided into 8 groups of treatment order. The cows visited the automatic milking unit more often when concentrate type O was offered, but not when an increased concentrate allowance was provided. The changes in concentrate intake and partial mixed ration (PMR) eating time showed a symmetrical pattern between the periods of increasing allowance and decreasing allowance. However, PMR intake and milk yield varied in the magnitude of the responses, indicating that these responses may not be driven by the same underlying mechanisms during increase and decrease in concentrate allowance. The daily lying time increased and the PMR eating rate decreased during periods of both increase and decrease in concentrate allowance. We found no significant change in milk yield during increase in concentrate allowance, despite a higher milk yield during periods with constant concentrate allowance at the high concentrate amount; however, the milk yield decreased during periods of decrease in concentrate allowance. Visit frequency, lying time, and steps changed during periods of changes in concentrate allowance without showing any differences at the constant concentrate allowance. In conclusion, these results indicate that it may be difficult to adjust the individual concentrate allowance based on the short-term responses of the cow.
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Global climate changes increase the risk of salinization of soil and water imposing possible health risks on livestock, especially in arid and semi-arid regions such as the Andes, the habitat of wild and domestic South American camelids (SAC), e.g. the llama (Lama glama). The aim of the present study was to evaluate the sensitivity and tolerance of llamas towards different NaCl concentrations in their drinking water. In total, 12 adult females with an average body weight (BW) of 140 kg ± 20.6 kg were kept under controlled conditions in individual pens. After a control phase (1 week) providing only fresh water, two choice tests were consecutively conducted: (1) a pairwise preference test (3 weeks) offering one bucket with fresh water and another with stepwise increasing NaCl concentration (0.25, 0.5, 0.75, 1.0, 1.25, 1.5%) and (2) a free-choice test (3 weeks) during which six buckets were simultaneously offered with NaCl concentrations of 0, 0.25, 0.5, 0.75, 1.0, and 1.25% NaCl. Chopped hay, water and a salt lick were provided for ad libitum intake. Records were kept on BW, body condition, feed, water and Na intake. Dry matter intake, total water and Na intakes increased during both choice tests (P < 0.001). Daily total Na intakes relative to metabolic body size (g/kg0.75) averaged 0.04 ± 0.02, 0.19 ± 0.02 and 0.26 ± 0.02 during the control phase, the preference and the free-choice test, respectively. In the pairwise test, llamas showed a weak preference for saline water with 0.5 – 0.75% NaCl, and rejected water from 1.25% NaCl. During the free-choice system, llamas had a remarkable interest in saline water with shares from total drinking water intake for fresh water and concentrations of 0.25, 0.50, 0.75, 1.0 and 1.25% NaCl being 23.6, 21.2, 19.5, 13.8, 13.3 and 8.6%, respectively. Llamas demonstrated a similar capacity to differentiate between saline water concentrations in two different experimental setups and adjusted their Na intake in self-selection. The results suggest that their reactions to saline water are similar to those of goat breeds adapted to arid zones.
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Diets and habitats that allow animals to select among alternatives enable individuals to better meet needs for nutrients and to better cope with toxins. All plants contain toxins, and the amount of toxin an animal can ingest depends on the kinds and amounts of nutrients and toxins in the forages on offer. Nutrients and toxins both cause animals to satiate, and excesses of nutrients, nutrient imbalances, and toxins all limit food intake. Thus, individuals can better meet their needs for nutrients and regulate their intake of toxins when offered a variety of foods that differ in nutrients and toxins than when constrained to a single food, even if the food is “nutritionally balanced.” Food intake and preference also depend on differences in how individual animals are built morphologically and how they function physiologically, and marked variation is common even among closely related animals in needs for nutrients and abilities to cope with toxins. Transient food aversions compound the inefficiency of single–food diets – whether in confinement, on pastures, or on rangelands – by depressing intake among individual animals, even if they are suited “on average” to that nutrient or toxin profile. Thus, feeding and grazing practices that allow producers to capitalize on the individuality of animals are likely to improve performance of the herd by enabling the uniqueness of individuals to become manifest. Finally, past experiences play a crucial role in an animal's propensity to learn to eat different foods. When herbivores are allowed to eat only the most preferred plants, they are not likely to learn to mix foods high in nutrients with foods that contain toxins. Conversely, herbivores encouraged to eat all plants in an area are more likely to learn to eat mixes of plants that mitigate toxicity. Experienced animals that have learned to eat a variety of foods that differ in nutrients and toxins do so even when nutritious alternatives are available, whereas naive animals familiar only with the nutritious alternatives eat only that subset of familiar foods. Different systems of management alter how animals forage. Continuous grazing at low stock densities encourages selectivity and reduces diet and habitat breadth, whereas short-duration grazing at high stock densities increases diet and habitat breadth. Thus, what was traditionally considered proper grazing management – rotational grazing at low stock densities – may have trained generations of livestock to “eat the best and leave the rest” thus inadvertently accelerating a decline in biodiversity and an increase in the abundance of less desirable plant species.
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The aim of this study was to evaluate the effect of feeding method on eating and sorting behavior, rumen acidosis, and apparent total tract digestibility of crossbred Angus bulls fed a high-concentrate diet. Twenty-one Angus beef bulls (497 ± 7.7 kg of initial BW, and 324 ± 3.0 d of age) were housed individually and fed ad libitum. Three experimental treatments were tested: complete feed of pellet and chopped straw in a single feeder (TMR), pellet and chopped straw fed separately in two feeders (SS); pellet and long unprocessed straw fed separately in two feeders (LS). Feed consumption, fecal and bloat scoring were recorded daily. Every 2 wk TMR sorting, eating behavior, general activity, social and oral behaviors, and BW were recorded. At days 14 and 35 apparent total tract digestibility during one week was measured. At days 28 and 42 rumen samples were collected via rumenocentesis to measure rumen pH and determine ruminal volatile fatty acids (VFA) concentrations. At the study end (day 57) animals at slaughterhouse liver and rumen wall color and lesions were recorded by a macroscopic inspection. No differences among treatments in total DMI, and fecal and bloat scoring were observed. The straw to concentrate ratio was smaller in the SS and LS treatments (8 to 92) than in the TMR (15 to 85), and sorting analyses indicated that TMR bulls refused large particles (> 4 mm) and small particles (< 1.5 mm). TMR bulls spent less time eating (P < 0.01) and tended to perform more self-grooming (P = 0.06), oral non-nutritive behaviors (P < 0.01) and stereotypes (P < 0.01) than bulls fed straw separately. Animals fed TMR had a greater (P < 0.01) pH than SS and LS, however rumen pH was above 5.6 in all treatments and rumen wall lesions did not differ among treatments. Feeding TMR increased (P < 0.05) the rumen acetate to propionate ratio. Bulls fed LS had greater total apparent DM (P < 0.05) and CP digestibility (P < 0.01), but no differences among treatments were observed in starch digestibility. In conclusion, even if straw to concentrate ratio and NDF intake was smaller in the SS and LS treatments than in the TMR, feeding pellet and straw separately, independently of straw length, did not predispose animals to suffer rumen acidosis as indicated by rumen pH, feed consumption, animal behavior, fecal and bloat scoring and rumen wall macroscopic evaluation.
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The hypothesis of my research was that providing functional diversity as opposed to dietary monotony will: alter fermentation patterns, increase animal production, and reduce negative environmental impacts, enhance animal welfare, and alter neophobia and partial preference through in utero and early life exposure. Thereby the objective was to determine the effects of altering the functionality of diverse diets (through context, species abundance, species distribution, and temporal availability) on dry matter intake, production, welfare, the environmental impacts, and partial preference compared with animals grazing a monotonous diet. This research was conducted over several experiments. Chapter 3 implemented an in vitro rumen fermentation methodology to determine if diverse versus monotonous diets altered fermentation patterns and allowed for assumptions on production and environmental impacts. The results showed that increasing the portion of chicory, plantain, or a diverse combination (chicory, plantain, and alfalfa) to ryegrass increased 24 hr gas production and branched-chain volatile fatty acid production, while reducing ruminal ammonia concentration. Chapter 4 applied an equal parts dry matter (DM) diverse combination diet to ram lambs and compared their intake, performance, welfare, and urinary nitrogen excretion to those offered a repetitive ryegrass diet. Lambs grazing the diverse diet had a 48% greater dry matter intake (DMI), 92% greater average daily gain (ADG), 25% lower day-to-day coefficient of variation (CV) of intake, and had a 30% lower urinary N concentration. Ram lambs provided a varied diet with set ratios of each species had a 20 and 10% greater DMI and a 29 and 23% reduced DMI CV compared to a diverse diet of the same ratios and a ryegrass diet that were monotonous in presentation in the experiment in chapter 5. The experiment in Chapter 6 explored the diverse and varied diet treatments without the restrictions of set ratios of species and compared them to a monotony of alfalfa. At the same level of intake the varied diet lambs gained 67 and 28% greater than the diverse and alfalfa diet. This greater ADG of the varied lambs occurred with the same intake and diet primary chemistry as the diverse diet, indicating that performance was affected by more than primary chemistry. Lambs consuming the alfalfa treatment conducted 150% more v bouts of stereotypic behavior than the diverse and varied lambs. Chapter 7 provided ewes in the final third of gestation with diverse or monotonous ryegrass diets. I found that diverse ewes birthed heavier lambs and exhibited lower levels of oxidative and metabolic stress 24 hrs after lambing. In chapter 8 the lambs birthed in chapter 7 remained with their dams on their respective treatment until weaning (early life experience) or were removed 24 hrs after lambing to pinpoint the effect of in utero and early life on partial preference and neophobic behaviors in later life. Lambs with early life exposure had partial preference altered more than those with only in utero exposure. Lambs exposed to ryegrass in utero or in utero and in early life spent more time grazing ryegrass than their diverse counterparts. In general, the diverse lambs had reduced latency to graze the diverse species compared to the ryegrass lambs. Further, all lambs chose to comprise a mixed species diet. This chapter demonstrated how in utero and early life experience can reduce neophobic behavior and that when provided the choice animals prefer to comprise a diverse diet even if a familiar forage species is available.
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The preference of sheep for two temperate grassland species, ryegrass and white clover, was tested by releasing flocks (of three ewes) onto swards (0.25 ha) that contained adjacent monocultures of grass and clover, and observing their intake behaviour over 6 days. The test paddocks contained either 20, 50, or 80% clover by ground area to distinguish partial preference from indifference. To test whether recent diet affected preference, separate groups of dry (non-pregnant, non-lactating) ewes grazed prior to testing on one of three diet 'back-grounds': an all-grass sward, an all-clover sward, or a 50:50 grass/clover sward by area. To consider the effects of physiological state on preference, a further group of lactating ewes, also from a 50:50 grass/clover 'background', were tested. In all cases, the mean diet obtained was a mixture of grass and clover, even though greater intake rates would have been obtained eating pure clover. There was a consistent temporal pattern to preference, with ewes showing the greatest preference for clover in the morning. The results suggest that previous diet 'background' can have lasting effects on preference. Ewes that had been recently grazing monocultures initially showed an increased preference for the opposite species to the one they had been grazing. Over 6 days these animals gradually reverted to a preference for their 'background' diet. Despite major differences in the energy requirement and intake behaviour of dry vs. lactating ewes, no significant effects of physiological state on preference were detected. Sheep grazing from swards of 20% clover spent a smaller proportion of time grazing clover and had a smaller proportion of clover in their diet than those grazing from 50% or 80% clover swards though, in all cases. behaviour was consistent with a preference for a high proportion of clover: sheep were not grazing at random. Overall, the results demonstrate that sheep sustain a mixed diet even in situations where a monospecific diet is readily possible. Several alternative hypotheses to explain this (partial preference, novelty, rarity, 'sampling') are discussed. We suggest the results provide evidence of partial and changing preference by sheep. Our results urge caution in infering long-term grazing behaviour from short-term tests of preference and suggest why knowledge of diet preference even in common herbivores remains equivocal.
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Large herbivores must select food from a wide variety of plant parts, species, and strains. These differ in nutritional value (protein, carbohydrate, etc.), toughness, spinosity, etc. Even greater differences are found in types and concentrations of secondary compounds. Every plant produces its own set of secondary chemical compounds, which to a great extent are unique to it or its species. Ingestion of natural concentrations of these compounds can lead to either death or severe physiological impairment. The ubiquitous nature of these compounds would make herbivory impossible unless animals had mechanisms for degrading and excreting them. An animal displaying no obvious symptoms of poisoning is not free of the problem of ridding itself of toxic compounds; if it is eating plants, it almost certainly has this problem. Herbivores are capable of detoxifying and eliminating secondary compounds. Limitations of these mechanisms force mammalian herbivores to consume a variety of plant foods at any one time, to tr...
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To test the proposition that sheep are able to select a diet that meets their crude protein (N × 6.25; CP) requirements, feeds L, A, B, C and H with the same energy content (11 MJ metabolizable energy/kg feed) but different CP contents (78, 109, 141, 172 and 235 g CP/kg fresh feed respectively) were formulated. In addition, feed U, which was feed L plus 21.4 g urea/kg (CP content 132 g/kg), was also made. The feeds were offered ad lib. either singly (n 4 per treatment) or as a choice between feed H and another feed (pairs LH, AH, BH, CH and UH; n 9 per feed pair) to individually penned Suffolk × Scottish mule wether lambs, over the live-weight range 25–45 kg. On the single feeds the rates of live-weight gain were 273, 326, 412, 418, 396 and 407 g/day (SE of difference (SED) 34; P < 0.01) and protein (excluding wool) gain were 27, 32, 44, 45, 41 and 39 g/d (SED 4; P < 0.001) for feeds L, A, B, C, H and U respectively. When sheep were given a choice between a feed below (L or A) and a feed above their CP requirements (H; as judged by the single-feeding treatments) the CP concentration selected was not different between the two pairs: 131 (SE 4) v. 133 (SE 4) g CP/kg feed for pairs LH and AH respectively. On the choices BH and CH (a choice between two feeds above requirements) the feed lower in CP was constantly preferred (874 (SE 33) and 910 (SE 33) g feed B and C respectively per kg total feed intake; CP selected was 157 and 178 g CP/kg respectively). However, this was not the case with the UH choice on which sheep consumed only 599 (SE 61) g feed U/kg total feed intake, resulting in a selection of a higher CP in their diet (173 g CP/kg). The live-weight gains of the animals given a choice between two feeds were 416, 387, 415, 410 and 383 g/d (SED 37) and protein gains were 45, 40, 46, 50 and 43 (SE 7) for pairs LH, AH, BH, CH and UH respectively, which were comparable with the best performance achieved on a single feed. The results suggest that sheep were able to select a diet that meets their CP requirements and avoid, at least to a certain extent, excess of protein intake. It is also possible that sheep discriminate against a property of feed U, such as an excess of urea, when this feed is paired with a feed high in CP.
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A herbivore faces challenges while foraging-ongoing changes in its physiological condition along with variation in the nutrient and toxin concentrations of foods, spatially and temporally-that make selecting a nutritious diet a vital affair. Foraging behaviours arise from simple rules that operate across levels of resolution from cells and organs to individuals and their interactions with social and physical environments. At all these levels, behaviour is a function of its consequences: a behaviour operating on the environment to induce changes is itself changed by those events. Thus, behaviour emerges from its own functioning-behaviour self-organizes-not from that of its surroundings. This ostensible autonomy notwith-standing, no self-organizing system (cell, organ, or individual) is independent of its environs because existence consists of an ongoing exchange of energy and matter. According to this view, the notion of cause and effect is replaced with functional relationships between behaviours and environmental consequences. Changes in physical environments alter the distribution, abundance, nutritional, and toxicological characteristics of plants, which affect food preference. Social interactions early in life influence behaviour in various ways: animals prefer familiar foods and environments, and they prefer to be with companions. Animals in unfamiliar environments often walk farther, ingest less food, and suffer more from malnutrition and toxicity than animals in familiar environments. An individual's food preferences-and its ability to discriminate familiar from novel foods-arise from the functional integration of sensory (smell, taste, texture) and postingestive (effects of nutrients and toxins on chemo-, osmo-, and mechano-receptors) effects. The ability to discriminate among foods is critical for survival: all problems with poisonous plants are due to an inability to discriminate or a lack of alternatives. Animals eat a variety of foods as a result of nearing or exceeding tolerance limits for sensory and postingestive effects unique to each food. After eating any food too frequently or excessively, the likelihood increases that animals will eat alternative foods owing to exceeding sensory-, nutrient-, and toxin-specific tolerance limits. Cyclic patterns of intake of a variety of foods reflect seemingly chaotic interactions among flavours, nutrients, and toxins interacting along continua.
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The genetic variation in energy expenditures of cattle at fasting (FHP) and maintenance (MEm) was determined by using 12 pairs of monozygous twins at 20 mo of age. The pairs were of two breed types, eight Angus x Hereford (three steers, five heifers) and four Barzona x Hereford (three steers, one heifer). The heifers were 132 +/- 13 d pregnant at the time of measurement. The pairs were fed at 1.15 x maintenance energy requirements for a minimum of 30 d prior to heat production (HP) measurements in dual indirect respiration calorimetry chambers. The diet fed was cracked corn:alfalfa hay (45:55) with a determined ME of 2.47 +/- .02 Mcal/kg DM. This diet was fed individually for 7 d prior to and during two consecutive 22-h HP measurements. The animals then were fasted for 2 d and fasting heat production measurements (FHP) were made on d 3 and 4 of the fast. Metabolizable energy required for MEm was calculated iteratively by assuming a semi-log relationship between HP and metabolizable energy intake. There were no differences (P greater than .10) in measured energy expenditures due to different breed type. The FHP and efficiency of ME use for MEm (Km) were similar between sexes, although heifers had lower (P less than .025) MEm than steers. Twin pair effects were detected for FHP (P less than .005) and MEm (P less than .05) but not for Km. Broad sense heritability estimates were calculated as the intraclass correlation between members of monozygous twin pairs. Heritability estimates for MEm, FHP, and Km were .52 +/- .22, .75 +/- .13, and .34 +/- .27, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
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To test the hypothesis that subclinical gastrointestinal parasitism, associated with an impairment in N digestion and metabolism and a reduction in the voluntary feed intake (VFI), could affect the diet selection of sheep given a choice between two feeds that differed in their crude protein (CP) content, twenty-four Texel x Scottish Blackface ewe lambs growing from 28 to 48 kg live weight (LWT) were given a daily dose of 2500 larvae of the intestinal nematode Trichostrongylus colubriformis; twenty-four similar lambs were used as uninfected controls. Six infected and six control lambs were given a free choice between two pelleted feeds (10.4 MJ metabolizable energy/kg), with different CP contents (90 (L) and 214 (H) g CP/kg fresh feed respectively). In addition, eighteen parasitized and eighteen control sheep were given access ad lib. to either feed L, or feed H, or their mixture M (164 g CP/kg; twelve per feed), in order to quantify the effects of the feeds when offered alone, and to test for any interactions between feed CP content and parasitism on the performance of the lambs. Intestinal parasitism reduced significantly (P < 0.001) both the rates of LWT gain (by 30%) and VFI (by 10%). The adult and developing parasitic forms took 4 weeks to establish and develop to a significant adult worm population (as judged by the faecal egg counts and blood variables) and until then there was no effect of parasitism on the performance of the lambs. The diet selection of the lambs given a choice between two feeds was similar between the two groups in the first 4 weeks of the experiment, but differed significantly (P < 0.05) in the second part of the experiment (4th week to the end). Thus, while parasitized lambs had a reduced rate of feed intake, by changing their diet selection they achieved a daily rate of CP intake similar to the control ones. However, since the parasitized lambs had a reduced rate of LWT gain, they also consumed a higher total amount of CP to reach the same LWT. It is concluded that sheep infected daily with a small number of larvae of T. colubriformis and given a choice between two feeds that differ in their protein contents are able to modify their diet selection in order to meet the increased protein requirements resulting from such an infection.
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Our objective was to better understand the importance of flavor and nutrients in food preferences of lambs. Three foods differing in flavor and nutritional quality were created by grinding and mixing grape pomace, barley, alfalfa pellets, and soybean meal in different proportions. food 1 (2.21 Mcal/kg DE, 8.1% DP), food 2 (2.42 Mcal/kg DE, 11.0% DP), and food 3 (2.68 Mcal/kg DE, 13.8% DP). Intake of each food, offered singly and together, was assessed when foods 2 and 3 were flavored with 1% onion or 1% oregano. Lambs (n = 24) preferred food 3 > 2 > 1, regardless of flavor (P < .05), and they continued to prefer food 3 > 2 > 1, even when they received the toxin LiCl after eating one of the three foods (P < .05). When offered a choice, lambs always ate substantial amounts of all three foods, even though they might have been expected to eat food 3 exclusively. We hypothesize selection of a varied diet resulted from a decrease in preference for food just eaten as a result of sensory input (taste, odor, texture, i.e., a food's flavor) and postingestive feedback (effects of nutrients and toxins on chemo-, osmo-, and mechano-receptors) unique to each food. Thus, we submit that offering different foods of similar nutritional value, offering foods of different nutritional value, and offering the same food in different flavors are all means of enhancing food preference and intake.
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An experiment was designed to investigate whether the degree of synchrony between the rates of digestion of carbohydrates and N of foods offered as a choice would have an effect, through their consequences, on the short- and long-term diet selection of sheep. Four foods (RL, RH, SL and SH) with the same high metabolizable energy, and similar high metabolizable protein contents were made into pellets. Foods RL and RH were based on a rapidly fermentable carbohydrate source and foods SL and SH on a slowly fermentable carbohydrate source; within each source one food (RL or SL) had a low, and the other (RH or SH) a high, rumen-degradable protein (RDP) content. The foods within a carbohydrate source were offered either singly or as a choice (RL/RH or SL/SH) to eleven rumen-fistulated mature sheep. The design was two 3 x 3 Latin squares (replicated once) with 5-week periods; squares consisted of two single foods and their respective choice. Weeks 1, 3 and 5 were considered to be controls, and weeks 2 and 4 used for rumen infusions of either urea or fructose infused over 4 h (10.00-14.00 hours). Food intake (FI) and diet selections (DS) were recorded daily and every 2 h (08.00-16.00 hours) on days 2-5 of each week; rumen pH and NH3 concentrations were also measured during these time intervals of day 5. As expected, feeding treatment affected significantly the rumen measurements: rumen NH3 concentrations were higher on foods RH and SH, and rumen pH lowest on RL. Daily FI was lowest on treatments SL, and choice SL/SH. The mean daily proportion of the low-RDP food in the selected diet was lower when the carbohydrate source was rapidly (choice RL/RH) rather than slowly fermentable (choice SL/SH); this was consistent with the experimental hypothesis. Short-term infusions affected further rumen variables (in the expected directions), irrespective of feeding treatment. However, DS over the 4h infusion period were unaffected; these short-term DS were consistent with the ones selected over the longer term (daily). The results suggest that the long-term (daily) diet selection of sheep may be affected by the degree of synchrony of energy and protein to the rumen. The fact that diet selections were not altered further by short-term manipulations of these supplies might reflect inadequacies of the methodology (infusions) adopted here.
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We suggested that food preference depends on the interplay between flavour and post-ingestive effects, and we predicted that protein-restricted lambs would acquire preferences for foods paired with supplemental sources of N, including urea (Expts 1 and 2), casein (Expt 3), and gluten (Expt 4). In each experiment, twenty lambs, in two groups of ten, were conditioned as follows: on odd-numbered days, lambs in group 1 received wheat straw (Expts 1, 3, and 4) or ground barley (Expt 2) flavoured with a distinctive flavour, and lambs in group 2 received the same food but with a different flavour. On even-numbered days, flavours were switched and lambs received capsules containing different amounts of urea (ranging from 0.12 to 0.92 g N/d), casein (ranging from 0.23 to 0.69 g N/d), or gluten (ranging from 0.23 to 0.69 g N/d). After conditioning period of 8 d, lambs were given a two-choice test to determine preference for flavours paired with N. In Expts 1 and 2, lambs preferred the flavours conditioned with urea at lower doses (0.12 g N/d in Expt 1, 0.23 and 0.46 g N/d in Expt 2), but they avoided the flavour associated with urea at the highest dose (0.23 g N/d in Expt 1 and 0.92 g N/d in Expt 2). In Expts 3 and 4, lambs avoided the flavours associated with the lowest doses of casein or gluten (0.23 g N/d), but they preferred the flavours paired with casein or gluten at higher doses (0.46 and 0.69 g N/d). After conditioning, N administrations were suspended and lambs in Expts 3 and 4 were offered a choice of the two flavours at weekly intervals for 2 weeks (extinction); preferences persisted during extinction. Collectively, these results suggest that the post-ingestive effects of N in different forms and concentrations influenced the development of food preferences by lambs.
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Ruminants eat a variety of foods from different locations in the environment. While water, cover, social interactions, and predators are all likely to influence choice of foraging location, differences in macronutrient content among forages may also cause ruminants to forage in different locations even during a meal. We hypothesized that lambs forage at locations containing foods that complement their basal diet and meet their nutritional needs. Based on this hypothesis, we predicted that lambs (n=12) fed a basal diet low in protein and high in energy would forage where a high-protein food (Food P) was located, and that lambs (n=12) fed a basal diet low in energy and high in protein would forage where a high-energy food (Food E) was located. Food P was a ground mixture of blood meal (50%), grape pomace (30%), and alfalfa (20%) that contained 47% crude protein (CP) and 2.211 Mcal/kg digestible energy (DE). Food E was a ground mixture of cornstarch (50%), grape pomace (30%), and rolled barley (20%) that contained 6% CP and 3.07 Mcal/kg DE. Food P provided 212 g CP/Mcal DE, whereas Food E provided 20 g CP/Mcal DE. Lambs growing at a moderate rate require 179 g CP and 3.95 Mcal DE. During Trial 1, we determined if lambs foraged to correct a nutrient imbalance, and if they preferred a variety of foods (Foods P and E) to only one food at a location (Food P or E). During Trial 2, we determined if nutrient-imbalanced lambs foraged in the location with the food that corrected the imbalance when the location of the foods changed daily. During Trial 3, lambs were offered familiar foods (Foods P and E) at the location furthest - and novel foods (wheat and soybean meal) at the location nearest - the shelter of their pen. During all three trials, lambs foraged most at the location with the food that contained the highest concentration of the macronutrient lacking in their basal diet, but they always ate some of both foods. Lambs did not feed exclusively at the location with a variety of foods (P and E). Rather, they fed at the location nearest the shelter that contained the macronutrient lacking in their diet. As availability of the food with the needed macronutrient declined in one location, lambs moved to the nearest location that had food with the needed macronutrient. When food that complemented their basal diet was moved to a different location, lambs foraged in the new location. Collectively, these results show that lambs challenged by imbalances in energy or protein selected foods and foraging locations that complemented the nutrient content of their macronutrient imbalanced basal diets.
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Ruminants select nutritious diets from a diverse array of plant species that vary in kinds and concentrations of nutrients and toxins, and meet their nutritional requirements that vary with age, physiological state, and environmental conditions. Thus, ruminants possess a degree of nutritional wisdom in the sense that they generally select foods that meet nutritional needs and avoid foods that cause toxicosis. There is little reason to believe that nutritional wisdom occurs because animals can directly taste or smell either nutrients or toxins in foods. Instead, there is increasing evidence that neurally mediated interactions between the senses (i.e., taste and smell) and the viscera enable ruminants to sense the consequences of food ingestion, and these interactions operate in subtle but profound ways to affect food selection and intake, as well as the hedonic value of food. The sensation of being satisfied to the full (i.e., satiety) occurs when animals ingest adequate kinds and amounts of nutritious foods, and animals acquire preferences (mild to strong) for foods that cause satiety. Unpleasant feelings of physical discomfort (i.e., malaise) are caused by excesses of nutrients and toxins and by nutrient deficits, and animals acquire aversions (mild to strong) to foods that cause malaise. What constitutes excesses and deficits depends on each animal's morphology, physiology, and nutritional requirements. This does not mean that ruminants must maximize (optimize) intake of any particular nutrient or mix of nutrients within each meal or even on a daily basis, given that they can withstand departures from the normal average intake of nutrients (i.e., energy-rich substances, nitrogen, various minerals, and vitamins). Rather, homeostatic regulation needs only some increasing tendency, as a result of a gradually worsening deficit of some nutrient or of an excess of toxins or nutrients, to generate behavior to correct the disorder. Extreme states should cause herbivores to increase diet breadth and to acquire preferences for foods that rectify maladies. From an evolutionary standpoint, mechanisms that enable animals to experience feedback, sensations such as satiety and malaise, should be highly correlated with nutritional well being, toxicosis, and nutritional deficiencies, which are directly related with survival and reproduction.
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Mice allowed to choose between diets containing tannin or saponin did not experience food intake depression, weight loss or high faeces weight to food weight ratios. Diets containing tannin produced all these effects and saponin diets resulted in weight losses and high faeces to food ratios. Mice provided with diets containing both tannin and saponin in predetermined proportions experienced weight losses similar to, or greater than, those of mice fed diets containing either toxin alone. Urinary glucuronide production by mice provided with a choice of tannin and saponin diets was less than that of mice feeding on diets containing either tannin or saponin alone. Simultaneous consumption of tannin and saponin (in the right proportions) may promote chemical interactions that inhibit the toxins' absorption from the intestinal tract. This type of interaction is likely to have influenced the evolution of herbivore feeding behaviour.
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In a 7-week experiment, the ability of lactating Holstein-Friesian cows to select a consistent diet from two similar foods differing in calculated metabolizable protein to energy (MP/ME) yield was investigated. The effect on diet selection of training through previous access to foods separately, was measured. Food intake was recorded with 28 computer-linked feeders. All foods were mixtures of grass silage and concentrates. In week 1, all feeders contained a standard food. In weeks 2 to 7 a low protein food (LP) and a high protein food (HP) were offered in 14 feeders each. Group CHOICE had access to both foods as a choice from week 2. Group TR1 was trained by access to one food during days 8 to 10 and to the other during days 11 to 13. Group TR2 received the same training as group TR1 during days 8 to 13 which was repeated once during days 14 to 19. After training, TR groups had access to both foods as a choice. Groups LOPRO and HIPRO had only access to LP or HP, respectively in weeks 2 to 5 and to both foods as a choice in weeks 6 and 7. In weeks 2 to 5 LOPRO COWS consumed less dry matter and produced less milk than CHOICE or HIPRO cows. After a week of adaptation, untrained CHOICE COWS selected 662 (s.e. 27) g HP per kg of intake, a choice that differed significantly (P < 0·01) from random. In weeks 4 to 7 TR cows established similar diet choice: 696 (s.e. 21) g HP per kg intake and the proportion selected was unaffected by length of training. The between-day variation in diet choice within cows was not affected by treatment. It is concluded that, under the circumstances tested, training was not required for cows to distinguish between two mixed foods with different calculated MP/ME ratios and to select proportions significantly different from random.
Article
In a multibreed experiment in which 292 heifers from 25 breeds were given a single complete pelleted diet ad libitum, body weight and food intake were recorded every 2 weeks. Relative growth rate, relative food intake and food conversion efficiency were calculated as the ratio of weight gain to body weight, food intake to body weight and weight gain to food intake respectively. The traits were measured over 12-week intervals from 12 to 72 weeks of age, and also over longer intervals of 24, 36, 48 and 60 weeks, each beginning at 12 weeks of age. Relative growth rate and food conversion efficiency declined continuously with increasing age, whereas relative food intake increased to a maximum in the 24- to 36-week period and then declined continuously.The between-breed genetic coefficient of variation (CVb) for relative food intake was very stable at about 0·04 whether measured over 12-week or longer intervals, whereas the CVVs for relative growth rate and food conversion efficiency were usually higher when measured over 12-week intervals compared with longer intervals. For the entire period from 12 to 72 weeks, the CVb was estimated as 0·029 for relative growth rate, 0·040 for relative food intake and 0·034 for food conversion efficiency. The corresponding intraclass correlations (t2) measuring the between-breed variation as a proportion of the total variation were estimated as 0·08, 0·18 and 0·15. Within-breed variation was thus much greater than between-breed variation for all three traits. Using published estimates of within-breed heritabilities, the parameters g21 measuring the between-breed genetic variation as a proportion of the total genetic variation, and g22, measuring the between-breed genetic variation as a proportion of the immediately selectable genetic variation, were estimated as 0·28 and 0·61 for food conversion efficiency and 0·25 and 0·57 for relative growth rate. Thus, for all three traits, despite their low CVb and t2 values, between-breed selection would be useful prior to within-breed selection.
Article
Our objective was to determine if variety of dietary flavors and ingredients affected selection of foraging locations by sheep. We hypothesized lambs would forage in locations that offered a variety of flavors and/or nutritional characteristics and on foods that differed from their basal diet. We tested this hypothesis in four trials. During Trial 1, lambs were fed a basal ration of alfalfa pellets (2.41 Mcal/kg DE, 18% CP), and then offered a test diet that was a ground mixture of 58% barley, 20% alfalfa, 17% grape pomace, 4% soybean meal, and 1% minerals (2.69 Mcal/kg DE and 14.7% CP). The test diet was offered at two different locations, one that provided the diet with a variety of added flavors (apple, anise, unadulterated) and the other that provided the diet in only the most preferred flavor (apple or anise). Procedures were the same during Trial 2, except the basal ration and the test diet were the same and different flavors were offered at the variety (apple, anise, fresh forage) and monotony (fresh forage) locations. During Trial 1, when the test diet differed from the basal diet, variety of flavors did not affect foraging location (P>0.05), but during Trial 2, when the basal diet was identical to the test diet, lambs preferred to forage where there was a variety of flavors (P<0.05). During Trials 3 and 4, the test diet was offered in different flavors along with alfalfa pellets (Trial 3) or ground alfalfa (Trial 4) at the variety location, whereas the test diet was offered in the preferred flavor at the monotony location. During Trial 3, lambs spent more time at the variety location, and they ate more pellets than the ground test diet, even though the test diet had higher concentration of energy (P<0.05), evidently because macro-nutrients consumed/unit time was greater for pellets than for the ground test diet. In Trial 4, lambs spent more time and ate more food where there was variety of foods and flavors (P<0.05), apparently because alfalfa and the test diet were complementary in flavor and nutrition. Collectively, our results suggest lambs selected foraging locations based primarily on nutritional factors, but when nutrient content was constant, variety of flavors was important.
Article
In 1986 (trial 1), lambs were exposed with their mothers to WB-PMP (whole barley and protein-mineral pellet) for 15 min/d for 0, 2, 4, 8 or 16 d. In 1987 (trial 2), they were exposed for 0, 4 or 8 d; two treatments for 8 d, with one receiving four times more WB-PMP (8H) than the other (8L). Following exposure to WB-PMP in both years, lambs and their dams grazed on summer range for 2 months before the drylot tests. Exposure for 4 d increased (P<0.05) intake of WB-PMP during the first week it was offered in drylot in 1986, but not (P>0.05) in 1987. Lambs exposed for 2, 8 or 16 d in 1986 did not consume more WB-PMP than controls (P>0.05). In 1987, lambs in treatment 8L consumed more (P<0.05) WB-PMP than controls during the first 2 weeks in drylot. Amount of WB-PMP offered affected intake of WB-PMP in drylot. Lambs in treatment 8H consumed more (P<0.05) than controls during the first 3 weeks in drylot. Lambs with high WB-PMP intakes during weeks 1 and 2 in both years consumed less WB-PMP during weeks 3 and 4, especially in 1987. The reduction in intake was greater for lambs previously exposed to WB-PMP than for controls. In 1986, 81% of the lambs exposed for 4 or 8 d and 64% of the lambs for 16 d achieved slaughter condition by week 8 in drylot, while only 50% and 33% of the lambs exposed for 0 or 2 d reached slaughter condition by that time (P<0.05). In 1987, lambs on WB-PMP did not reach slaughter condition sooner than controls, probably due to severe decrease in intake that occurred during weeks 3 and 4 in drylot. Lambs exposed to WB-PMP for 8 d in 1987 entered the drylot with ruminal papillae that had 38% more surface area than did lambs not exposed to WB-PMP; however, the differences disappeared within 3 weeks. Results indicate that exposing lambs to a WB-PMP diet early in life enhanced performance in drylot. Development of rumen papillae as a result of exposure may contribute to this performance.
Article
Tall larkspur (Delphinium barbeyi) is a toxic forb often consumed by cattle on mountain rangelands, with annual fatalities averaging about 5%. This study examined the relationship between food ingestion and toxicity in cattle. Two grazing studies suggested that larkspur consumption above 25–30% of cattle diets for one or two days led to reduced larkspur consumption on subsequent days. We subsequently hypothesized that cattle can generally limit intake of larkspur to sublethal levels. This hypothesis was tested by feeding a 27% larkspur pellet in experiment 1. Cattle given a 27% larkspur pellet ad libitum showed distinct cyclic patterns of intake, where increased larkspur consumption on one or two days was followed by reduced (P P > 0.05) between controls and treatment animals at the 20 or 40 mg LiCl/kg dose in the percentage of corn consumed, but the 80 mg LiCl/kg dose induced a cyclic response (mean 46%) compared to intake by controls (mean 96%) (P P P
Article
Ruminants eat an array of plant species that vary in nutrients and toxins. This selection makes intuitive sense, but no theories adequately explain this diversity. Some maintain it reduces the likelihood of overingesting toxins, whereas others contend it meets nutritional needs. Nevertheless, herbivores seek variety even when toxins are not a concern and nutritional needs are met. I offer another explanation for this behavior, one which encompasses the avoidance of toxins and the acquisition of nutrients. A key concept in this theory is aversion, the decrease in preference for food just eaten as a result of sensory input (a food's taste, odor, texture, i.e., its flavor) and postingestive effects (effects of nutrients and toxins on chemo-, osmo-, and mechano-receptors) unique to each food. Aversions are pronounced when foods contain toxins or high levels of rapidly digestible nutrients; they also occur when foods are deficient in specific nutrients. Aversions occur even when animals eat nutritionally adequate foods because satiety (satisfied to the full) and surfeit (filled to nauseating excess) represent points along a continuum, and there is a fine line between satiety and aversion. Thus, eating any food is likely to cause a mild aversion, and eating a food too frequently or in excess is likely to cause a strong aversion. Aversions are involuntary and are not the result of conscious decisions by an animal. Aversions yield benefits (e.g., obtain a balanced diet, reduce ingestion of toxic foods, optimize foraging and rumination times, sample foods, maintain a diverse microflora in the rumen) that are often mistaken as the cause of varied diets. In this article, I discuss the subtle ways in which aversions diminish preference and cause animals to eat a variety of foods.
Article
We hypothesized that volatile fatty acids are feedback signals that condition food preferences in ruminants, and we tested two predictions based on this hypothesis: 1) low doses of propionate condition preferences for low-quality foods (Exp. 1 and 2) preferences are not caused by osmotic load (Exp. 2). In Exp. 1, lambs were offered chopped wheat straw flavored with either oregano or onion on odd days, whereas on even days flavors were switched and lambs received capsules containing sodium propionate. During four 8-d conditioning periods, the amounts of propionate delivered ranged from .7 to 1.4% of the daily DE intake (Period 1) or were fixed at .7% (Period 2) and 1% of the daily DE intake (Periods 3 and 4). After each 8-d conditioning period, lambs were offered oregano- and onion-flavored straw. Conditioning was then suspended and lambs were offered onion- and oregano-flavored straw at weekly intervals for 1 mo (extinction). Lambs preferred the flavor paired with propionate during conditioning (P < .001) and extinction (P < .07). During Exp. 2, a different group of lambs was conditioned as in Exp. 1, but sodium chloride was delivered at osmotic loads equivalent to those when propionate supplied .7% and 1% of the daily DE intake. Lambs strongly avoided the flavor paired with sodium chloride (P < .001). Thus, lambs acquired preferences for straw conditioned with doses of propionate typically considered ineffective in the regulation of food intake, and osmolalities generated by propionate did not cause, but probably attenuated, food preferences.
Article
Ruminants eat a variety of foods, varying in toxins and nutrients, but no hypotheses adequately explain this behavior. We offer an explanation, one which encompasses avoidance of toxins and acquisition of nutrients. A key concept in this hypothesis is aversion, the decrease in preference for food just eaten as a result of sensory input (taste, odor, texture, i.e., a food's flavor) and postingestive effects (of toxins and nutrients on chemo-, osmo-, and mechano-receptors) unique to each food. On the basis of this hypothesis, we predicted lambs would prefer familiar and novel foods that complemented the macronutrient composition of their basal diet. To assess the validity of this prediction, we fed 10 lambs in each of three treatments different levels of ground barley (high in energy) and alfalfa (high in protein) as a basal diet. We then offered them daily a meal of three ground foods differing in proportions of barley and alfalfa (familiar foods) or wheat and rabbit pellets (novel foods). We found that lambs fed a basal diet high in energy (barley) preferred food lower in energy and higher in protein (alfalfa); those fed a diet high in alfalfa preferred food high in barley (P < .01). In addition, the higher the barley or alfalfa content of the basal diet, the greater the acceptance of novel foods high in alfalfa (i.e., rabbit pellets) or grain (i.e., wheat), respectively (P < .01). All lambs preferred foods high in wheat to rabbit pellets or alfalfa (P < 0.01), evidently because wheat is high in energy and it differs in flavor from barley, which was eaten repeatedly as part of the basal diet. On the basis of these results, we contend that lambs preferred familiar and novel foods that complemented the flavors and macro-nutrient contents of their basal diet.
Article
We conducted experiments to determine whether preference for barley was affected when lambs ate various amounts of barley and whether lambs ate more barley when it contained lasalocid and sodium bicarbonate (NaHCO3), both of which attenuate acidosis. In Exp. 1, lambs were assigned to two treatments (six lambs/treatment). For 2 d, lambs in two treatments were offered either 400 or 1,200 g of rolled barley from 0600 to 0700 as a preload meal. A preference ratio [PR = barley ingested/(total amount of alfalfa + barley ingested)] was calculated based on lambs' intake when offered a choice of 200 g each of rolled barley and alfalfa pellets hourly from 0700 to 1100. After the preload meal, lambs in Treatment 1 (400 g preload) showed equal preference for barley (.52) and alfalfa (.48) for 4 h on d 1 (P > .05); their preference for barley was less after the meal of barley on d 1 (.52) than on d 2 (.72), but their preference for barley declined between h 3 (.81) and 4 (.55) of d 2 (P = .11). Lambs in Treatment 2 (1,200 g preload) showed a low preference for barley on d 1 (.29) and 2 (.19) (P < .001). In Exp. 2, lambs were assigned to four treatments (six lambs/treatment): 1) rolled barley + NaHCO3 (2%) + lasalocid (33 ppm); 2) rolled barley + NaHCO3 (2%); 3) rolled barley + lasalocid (33 ppm); or 4) rolled barley. Intake of barley by lambs offered NaHCO3 + lasalocid (Treatment 1) was greater (P = .07) than that by lambs offered NaHCO3 (Treatment 2), whereas intake by lambs offered lasalocid (Treatment 3) was similar (P > .05) to that by controls. We conclude that eating barley too frequently or in excess caused a decrease in lambs' preference for barley and that NaHCO3 and lasalocid attenuated the aversion.
Article
We hypothesized that lambs discriminate between postingestive effects of energy and protein and associate those effects with a food's flavor to modify food choices. Based on this hypothesis, we predicted that 1) lambs would acquire a preference for a poorly nutritious food (grape pomace) eaten during intraruminal infusions of energy (starch) or protein (casein) and that 2) shortly after an intraruminal infusion of energy or protein (preload), lambs would decrease their preferences for foods previously conditioned with starch or casein, respectively. Thirty lambs were allotted to three groups and conditioned as follows. On d 1, lambs in each group received grape pomace containing a different flavor and water was infused into their rumens as they ate the pomace. On d 2, the flavors were switched so each group received a new flavor and a suspension of starch (10% of the DE required per day) replaced the water infusion. On d 3, the flavors were switched again, and a suspension of casein (2.7 to 5.4% of the CP required per day) replaced the starch infusion. Conditioning was repeated during four consecutive trials. Lambs in Trial 1 had a basal diet of alfalfa pellets (e.g., free access from 1200 to 1700) and 400 g of rolled barley. Lambs in Trials 2, 3, and 4 received a restricted amount of alfalfa pellets (990 g/d) as their basal diet. After conditioning, all animals received an infusion of water, and, 30 min later, they were offered a choice of the three flavors previously paired with water, starch, or casein. On the ensuing days, the choice was repeated, but starch, casein, and barley replaced the water preload. The nutrient density of the infused preloads was increased during consecutive trials. Lambs preferred the flavors paired with starch > water > casein during Trial 1 (P < .05) and the flavors paired with starch > casein > water during Trials 2 (P < .05), 3 (P < .001), and 4 (P < .001). Preloads of casein decreased preferences for flavors previously paired with casein (P < .10 [Trial 2]; P < .001 [Trial 3], and increased preferences for flavors paired with starch (P < .05 [Trial 2]; P < .001 [Trial 3]). Preloads of energy (barley) had the opposite effect (P < .05 [Trial 3]). These results indicate that lambs discriminated between the postingestive effects of starch and casein and associated the effects with specific external cues (i.e., added flavors) to regulate macronutrient ingestion.
Article
In studies of behavior and nutrition, we typically determine nutritional needs and formulate diets for the average member of the herd, not for specific individuals within a herd. Nevertheless, variation among individuals could affect productivity of the group if the diet diverges too much from what individuals at the extremes prefer to eat. Thus, it is important to determine the degree to which individuals within a group vary in their food preferences when offered alternatives. Our first objective was to determine the degree to which lambs differed in preference for foods high in energy (barley) or protein (alfalfa) (Exp. 1). When we offered lambs barley and alfalfa for ad libitum consumption for 25 d, individuals varied in the amounts of barley (range: 221 to 991 g/d) and alfalfa (range: 51 to 558 g/d) they consumed (P < .0001). At one extreme, individuals preferred a diet of 6% alfalfa and 94% barley; at the other extreme, individuals preferred a diet of 70% alfalfa and 30% barley. Our second objective was to determine whether lambs from Exp. 1 compensated, when fed a basal diet that was lower in alfalfa than they preferred, by ingesting foods higher in alfalfa when offered a meal (Exp. 2). Lambs were ranked according to the percentage of alfalfa (range from 6 to 70%) and barley (range from 94 to 30%) they ate during Exp. 1 and then assigned alternately to two treatments: 1) basal diet with similar proportions of alfalfa and barley consumed ad libitum (preferred diet) or 2) basal diet with 10% less alfalfa than consumed ad libitum (low-alfalfa diet). We then conducted three trials in which lambs fed the different basal diets were offered a meal for 15 min/d for 2 d of two foods that differed in barley and alfalfa. During Trial 1, when we offered barley and alfalfa, lambs in both groups preferred barley (138 g) to alfalfa (46 g) (P < .05). During Trial 2, when the test foods (barley and alfalfa) were diluted with grape pomace (20%), lambs fed the preferred basal diet ate more barley (116 vs 64 g) and less alfalfa (48 vs 87 g) than lambs fed the low-alfalfa basal diet (P < .05). During Trial 3, when we offered a food high in barley (80% barley and 20% pomace) and a food high in alfalfa (70% alfalfa, 14% cornstarch, and 16% pomace), lambs fed the preferred basal diet ate more of the high-barley food (124 vs 73 g) and less of the high-alfalfa food (45 vs 98 g) than lambs fed the low-alfalfa basal diet (P < .05). Collectively, these results illustrate that lambs varied greatly in their preferences for foods that differ in energy (barley) and protein (alfalfa), and that when their preferred basal diet was altered, lambs compensated by ingesting food that complemented their basal diet during a daily meal. The addition of grape pomace in Trials 2 and 3 reduced the protein content of the high-barley and high-alfalfa foods such that the high-barley food was only marginally adequate to meet needs compared with the high-alfalfa food. Lambs fed the low-alfalfa basal diet compensated by eating more of the high-alfalfa food than lambs fed the preferred basal diet.
Article
We determined how a food's flavor and digestibility, along with an animal's recent experiences, influenced food preference and intake. In three experiments, pregnant heifers were fed a basal ration (7.75 kg/animal) of alfalfa, barley, corn silage, and a vitamin/mineral supplement from 1500 to 2200. Exp. 1 determined the influence of recent exposure to flavored straw. Animals were divided into two groups (n = 16/group) and fed either untreated or ammoniated straw with digestibilities of 43 and 58%, respectively. Within each group, half of the heifers were fed maple-flavored straw and the other half were fed coconut-flavored straw from 1100 one day to 0900 the next day, with no base ration. We then offered straw in both flavors from 1000 to 1200 for the next 5 d. Animals fed maple-flavored straw for 1 d generally preferred coconut- over maple-flavored straw for the next 5 d, whereas animals previously fed coconut-flavored straw preferred maple-flavored straw (P < 0.001). The change in preference was stronger when animals were fed untreated compared with ammoniated straw. Experiments 2 and 3 determined the influence of offering straw in different flavors, either in sequence (Exp. 2) or simultaneously (Exp. 3). In Exp. 2, we offered heifers (n = 16) straw in three flavors (maple from 0900 to 1100, coconut from 1100 to 1300, and unflavored from 1300 to 1500) and compared their intake with that of heifers (n = 16) offered unflavored straw throughout the day. In Exp. 3, we compared intake of heifers (n = 16) simultaneously offered straw in three flavors (coconut, maple, and unflavored) with that of heifers (n = 16) offered only unflavored straw from 1000 to 1500. In both experiments, straw intake and preference differed between heifers offered straw in a variety of flavors as opposed to only unflavored straw (P < 0.05), but animals fed a variety of flavors did not consistently eat more than those fed only one flavor. During a post-trial preference test, heifers previously restricted to straw in one flavor for 5 d preferred straw in alternative flavors, whereas heifers fed straw in all three flavors preferred unflavored straw. Changes in preference were stronger for heifers fed untreated compared with ammoniated straw. Collectively, our results suggest that palatability, as evidenced by changes in preference and intake, is dynamic and depends on a food's flavor and nutritional quality and an animal's recent experiences with the food.
Appetite, palatability and control of feed intake
  • W L Grovum
Grovum, W. L. 1988. Appetite, palatability and control of feed intake.
  • D Undersander
  • D R Mertens
  • N Thiex
Undersander, D., D. R. Mertens, and N. Thiex. 1993. Forage Analyses Procedures. National Forage Testing Assoc., Omaha, NE.