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Effect of protein supplementation on milk production and metabolism of dairy cows grazing tropical grass
Abstract
The objectives of this study were to determine if midlactation dairy cows (Bos taurus L.) grazing intensively managed elephantgrass would have their protein requirement met exclusively with the pasture and an energy concentrate, making the use of protein ingredients unnecessary, as well as to determine the dietary crude protein (CP) content that would optimize the efficiency of N utilization (ENU). Thirty-three Holstein and crossbred (Holstein × Jersey) midlactation dairy cows, producing approximately 20 kg/d, were grouped within breed into 11 blocks according to milk yield and days in milk. Within blocks, cows were randomly assigned to 1 of 3 treatments and remained in the study for 11 wk. The control treatment contained only finely ground corn, minerals, and vitamins, and it was formulated to be 8.7% CP. Two higher levels of CP (formulated to be 13.4 and 18.1%) were achieved by replacing corn with solvent-extracted soybean meal (SSBM). Pasture was fertilized with 50 kg of N/ha after each grazing cycle and averaged 18.5% CP (dry matter basis). No differences were observed in milk yield or milk fat, protein, and casein content or casein yield. In addition, pasture intake was not different among treatments. Milk urea N increased linearly as the concentrate CP content increased. Cows fed the 8.7% CP concentrate had higher ENU. In another experiment, 4 ruminally cannulated Holstein dry cows were used in a metabolism trial designed in a 4 × 4 Latin square. Cows were fed the same treatments described as well as a fourth treatment with 13.4% CP in the concentrate, in which urea replaced SSBM as the main N source. Ruminal volatile fatty acid concentration and microbial synthesis were not affected by levels or sources of N in the concentrate. Ruminal NH(3)N content increased as the concentrate CP content increased. Inclusion of SSBM in the concentrate did not increase production and decreased the ENU of midlactation dairy cows grazing on tropical forage. Supplementation of an 8.7% CP concentrate, resulting in a diet with CP levels between 15.3 and 15.7% of dry matter, was sufficient to meet the protein requirements of such milk production, with the highest ENU (18.4%).
... N excretions in urine, feces and milk were lower than those reported by Spek et al. (2013) for lactating dairy cows in north-western Europe (212, 223 and 166 g/d) and North America (185, 159 and 133 g/d). Furthermore, a lower N excretion in feces in both treatments was noticed (144 g/d) in comparison with other authors (Spek, et al., 2013;Danes et al., 2013) in lactating cows. Hristov et al. (2005) found a lower N excretion in feces (76%) in diets supplemented with fibre in comparison with starch; they attributed this difference in faecal N to the differences in the amounts of microbial N synthesised in the large 773 PRG-RCL: Perennial ryegrass-red clover; ARG-WCL: Annual ryegrass-white clover; DM: Dry matter; N: Nitrogen; OM: Organic matter; NDF: Neutral detergent fibre; ADF: Acid detergent fibre; MUN: Milk urea nitrogen; N in milk yield: milk yield true protein /6.38. ...
... In a study on tropical grasses, Danes et al. (2013) reported higher BUN and MUN values and a linear decrease in NUE when PC content in diet increased. Brito and Broderick (2007) found an effect on the MUN and BUN levels for cows supplemented with various true proteins. ...
... In PRG-RCL, NUE was similar (15.6%) to the values reported by León et al. (2008) for cows grazing kikuyu. Systems with moderate milk production levels based on grazing, such as in New Zealand, usually exhibit a larger N intake in diet in virtue of the high CP content in the grass (Pacheco and Waghorn, 2008); or in Brazil, where because of a high level of protein supplementation (Danes et al., 2013), a negative effect on N efficiency in milk is noticed. ...
p> Background: Nitrogen (N) plays an important role in dairy systems, both in production costs and as an indicator of environmental impact. Objective: The objective was to investigate the effects on milk production and nitrogen excretion by dairy cows fed cut pastures either of perennial ryegrass-red clover (PRG-RCL) or annual ryegrass-white clover (ARG-WCL), complemented with ground maize straw and of commercial concentrate. Methodology: Six dairy cows were used in a double cross-over on-farm experiment with 14-day experimental periods. Milk yield and composition, live weight, body condition score, chemical composition of feeds and N content in f a eces, urine, milk and blood were recorded over the last four days of each experimental period. Results: No differences were found ( P > 0.05) for milk yield nor composition. Cows on ARG-WCL had a higher N intake and N balance than those on PRG-RCL ( P < 0.05); also, there were higher levels of blood urea nitrogen (BUN) and urine urea nitrogen (UUN) when cows were fed ARG-WCL than PRG-RCL ( P < 0.05). Implications: This work allows us to know the amount of nitrogen excreted in milk production in small-scale dairy systems. Conclusions: It is concluded that PRG-RCL may be a feeding strategy to reduce N excretion and achieve higher efficiency in N use for small-scale dairy systems.</p
... improve the nutrient utilization efficiency in dairy operations, including pasture-based systems in the tropics with intensively managed tropical grasses. Several studies have shown that intensively managed tropical grasses have high crude protein (CP) content, ranging from 16.0 to 18.5% (Danes et al., 2012;De Freitas et al., 2019;Moura et al., 2014;Oliveira et al., 2020); therefore CP is not usually a limiting nutrient in diets formulated to grazing cows. However, more than 70% of this CP has medium to high ruminal degradation rates (Danes et al., 2012;Moura et al., 2017), which can compromise the nitrogen assimilation by the microbial mass (Schor and Gagliostro, 2010) if the only source of energy comes from slowly ruminal fermentable carbohydrates (i.e., fiber), resulting in increased nitrogen excretion. ...
... Several studies have shown that intensively managed tropical grasses have high crude protein (CP) content, ranging from 16.0 to 18.5% (Danes et al., 2012;De Freitas et al., 2019;Moura et al., 2014;Oliveira et al., 2020); therefore CP is not usually a limiting nutrient in diets formulated to grazing cows. However, more than 70% of this CP has medium to high ruminal degradation rates (Danes et al., 2012;Moura et al., 2017), which can compromise the nitrogen assimilation by the microbial mass (Schor and Gagliostro, 2010) if the only source of energy comes from slowly ruminal fermentable carbohydrates (i.e., fiber), resulting in increased nitrogen excretion. ...
... In our study, the forage mass above the post grazing residue height averaged (mean ± SD) 3,832 ± 968 kg of dry matter/hectare (corresponding to 25 ± 6.4 kg of dry matter/cow/d). Danes et al. (2012) and De Freitas et al. (2019) reported herbage intakes of 12.5 and 8.22 kg/d for cows on tropical pastures with forage masses of 3,350 and 3,116 kg of dry matter/ha, respectively. Digestibility of nutrients did not differ among treatments; therefore, the forage allowance and forage quality do not seem to be the limiting factors for the intake of the animals in our study. ...
We aimed to determine the effects of partially replacing conventional solvent-extracted soybean meal by amino resin-treated soybean meal in the concentrate supplement of lactating dairy cows grazing Guinea grass (Panicum maximum cv. Mombaça) on dry matter intake, milk production and composition, feed and nitrogen use efficiency, and nutrient digestibility. Eighteen Holstein x Gyr crossbred multiparous cows (79 ± 38 days in milk and 37.4 ± 4.69 kg/d of milk yield) were used in a replicated 3x3 Latin square design study with three experimental periods of 21 d. The solvent extract soybean meal of the control diet (CON) was replaced by 1.0 (TSBM1.0) and 1.5 (TSBM1.5) kg as-fed basis of amino resin-treated soybean meal (29 and 43% as dry matter basis, respectively) in the treatment diets. Dry matter intake, milk casein, protein, and fat contents, feed efficiency, nitrogen use efficiency, and nutrient digestibility did not differ among treatments (P > 0.05). The metabolizable protein was not increased by the treatments; however, cows fed with TSBM1.5 tended to produce 1.2 kg/d more milk (P = 0.09) and 64.3 g/d more lactose (P = 0.06) than CON cows. Although the supply of metabolizable protein was not affected by treatments, increasing rumen undegradable protein supply by 43% by replacing conventional solvent-extracted soybean meal with amino resin-treated soybean meal tended to increase milk production of high producing grazing cows.
... The excess of dietary CP can cause a reduction in the energy available for milk yield due to the energy expenditure to eliminate ammonia N via urea synthesis and represent an increase in financial costs due to concentrate supplementation. When intensively managed tropical grasses have CP contents ranging from 15 to 21% dry matter (DM), it is only necessary to use energy supplements in order to meet the nutritional requirements of cows producing 20 kg day −1 of milk (Danes, Chagas, Pedroso, & Santos, 2013). Therefore, energy supplementation in intensive pasture-based milk production systems becomes an important strategy to both mitigate the protein-energy imbalance in the rumen and meet the nutritional requirements of the cows. ...
... Although cows from treatment with concentrate supplementation consumed the same amount of energy (TDN) in relation to those that did not receive supplementation, there was less intake of (Table 3) and, consequently, less nitrogen intake. Therefore, these cows probably expended less energy on converting ammonia N to urea in the liver, which allowed a greater supply of energy for milk production (Danes et al., 2013). According to these authors, high dietary CP contents reduce the metabolizable energy available for milk production, mainly due to the higher energy cost for urea synthesis and excretion. ...
... According to these authors, high dietary CP contents reduce the metabolizable energy available for milk production, mainly due to the higher energy cost for urea synthesis and excretion. The higher intake of CP in cows that did not receive concentrate supplementation, associated with low energy intake (Table 3), a common characteristic in cows grazing in tropical pastures, may be related to the lower efficiency of N use by these cows (Danes et al., 2013), as well as the lower availability of energy for milk production. The lower intake of CP (Table 3) associated with the higher production of protein in the milk of cows that received ground corn (Table 4) indicates that there may have been a reduction in the excretion of N and, consequently, better efficiency in the use of this nutrient. ...
This study evaluated the effect of energy supplementation with ground corn on the performance of crossbred dairy cows in BRS Kurumi elephant grass pastures managed under rotational stocking during the rainy season. Six Holstein × Gyr cows were used, with average milk production, body weight, body condition score, and days in milk of 18.0±2.89 kg day−1, 560±66 kg, 2.50±0.21, and 99±12, respectively. The experimental design used was the complete reversion (switchback), and the evaluations were conducted over three grazing cycles, with adaptation periods of 14 days and six days of sample collection. The concentrate supplement (ground corn) was supplied twice a day, at a rate of 2 kg cow−1 day−1 in the morning and 1 kg cow−1 day−1 in the afternoon (as-fed basis). A reduction of 23.4% was observed in the pasture dry matter (DM) intake (PDMI) in cows that received energy supplementation, which corresponds to 2.96 kg day-1 less of PDMI when compared to the group without supplementation. This corresponds to a substitution rate of 1.1 kg of pasture per kg of concentrate consumed (DM basis), which reduced the intake (kg cow−1 day−1) of neutral detergent fiber and crude protein by 18.9% and 13.9% in the cows that received ground corn. There were increases of 11.8%, 9.0%, and 10.1%, respectively, in the milk yield, the 3.5% fat-corrected milk yield, and the energy-corrected milk yield of the cows that received ground corn. The response to supplementation in kg of milk per kg of DM of concentrate consumed was 0.57, and the milk contents of fat, protein, and lactose did not differ between treatments. The energy supplementation with 3 kg cow−1 day−1 of ground corn resulted in an increase of 11.8% in the milk yield of Holstein × Gyr dairy cows grazed on BRS Kurumi elephant grass, as well as promoted increases in the daily protein, lactose, and total solids yields. In addition, the provision of 3 kg day−1 of ground corn for lactating cows grazing on BRS Kurumi increased the efficiency in the use of dietary nitrogen.
... Accordingly, our previous study reported no advantages of feeding three different levels of CP (8.7%,13.4%,and 18.1% CP;DM basis) to mid-lactation dairy cows (producing 20 kg of milk daily) grazing elephant grass with 18.5% CP on cow productive performance and the lowest dietary CP concetration (8.7% CP) was sufficient to meet the protein requirements of those cows (Danés et al., 2013). ...
... We used a rate of 1 kg (as-fed basis) of concentrate/3 kg of milk. This concentrate feeding rate has been reported in our previous studies, and it is a very common and practical strategy used in the Brazilian farms to optimize dairy production under intensive tropical grazing management (Congio et al., 2018;Danés et al., 2013). ...
... We hypothesized that protein requirements of early-lactating grazing dairy cows would be met by the protein from the pasture, with no need for a protein ingredient in the concentrate mix. Previous research conducted by our group had demonstrated that mid-lactation dairy cows producing around 20 kg/day had their requirements met by an 18.5% CP tropical pasture plus concentrate supplementation containing only an energy source (Danés et al., 2013). However, our current results showed that early-lactation cows did positively respond to increasing levels of CP in the concentrate. ...
This experiment was designed to evaluate the effects of different concentrate crude protein (CP) concentration on performance, metabolism and efficiency of N utilization (ENU) on early‐lactation dairy cows grazing intensively managed tropical grass. Thirty cows were used in a ten replicated 3 × 3 Latin square design. The treatments consisted of three levels of concentrate CP: 7.9%, 15.4%, and 20.5% offered at a rate of 1 kg (as‐fed basis)/3 kg of milk. The cows fed low and medium CP had negative balance of rumen degradable protein and metabolizable protein. Increasing CP tended to linearly increase DMI, 3.5% FCM and milk casein, and linearly increased the yields of milk fat and protein. Increasing CP linearly increased the intake of N, the concentration of rumen NH3–N, and the losses of N in milk, urine, and feces. Increasing dietary CP linearly increased the molar proportion of butyrate but had no effect on the other rumen VFAs and no effect on microbial yield. In conclusion, feeding a concentrate with 20.5% of CP to early‐lactation dairy cows grazing tropical grasses, leading to a 17.8% CP diet, tended to increase DMI, increased the yield of 3.5% FCM and the milk N excretion, and decreased ENU by 32%.
... However, these intensively managed systems are usually coupled with moderate or high doses of nitrogen (N) fertilizers resulting in high herbage crude protein (CP) content at the expense of energy content (Danes et al., 2013), which could lead to CP overfeeding of grazing dairy cows (NRC, 2001). When it is not retained in the animal tissues or secreted into milk, N is excreted by urine and feces, causing environmental issues, such as water pollution and gaseous N emissions (Hristov et al., 2019). ...
... The ingredients were: citrus-pulp (35 %), corn gluten feed (30 %), fine ground corn (20 %), soybean meal (10 %) and mineral (5 %). The concentrate was formulated using NRC (2001) considering forage CP level averaging 18 % DM for dairy cows yielding 20 kg d -1 of milk (similar to previous experiments in the same rotational grazing system; Voltolini et al., 2010;Danes et al., 2013;De Souza et al., 2017). ...
... %). Overall, the results regarding handplucked herbage chemical composition were similar to those from other studies conducted in the same site using similar N fertilization levels (Danes et al., 2013;De Souza et al., 2017). Increased N fertilization levels usually increases herbage CP content, due to greater proportions of soluble and intermediate protein fractions (Johnson et al., 2001). ...
There is limited information regarding both nitrogen (N) and energy partitioning of dairy cows grazing well–managed tropical pastures. The objective of this study was to investigate the N and energy partitioning of mid–lactation dairy cows on rotationally grazed elephant grass using two pre–grazing targets: 95 % or maximum canopy light interception (LI95% or LIMax) during regrowth. The study used 26 Holstein × Jersey dairy cows arranged in a randomized complete block design with three 40–day periods of sampling. Grazing at LI95% increased organic matter and crude protein intake by 20 % (p ≤ 0.05) which resulted in a 9 % increase in fat corrected milk yield (p ≤ 0.05) relative to LIMax. Cows grazing at LI95% had greater concentration of total volatile fatty acids, butyrate and valerate (p ≤ 0.05), and smaller acetate (p ≤ 0.05) than those grazing at LIMax. Intake of net energy for lactation (NEL) and NEL secreted in milk were greater (p ≤ 0.05), while partitioning of NEL towards maintenance tended to be greater (p = 0.07) for cows grazing at LI95% than those grazing at LIMax. Milk urea nitrogen and both urine and fecal N excretion were greater for cows grazing at LI95% (p ≤ 0.05), but N excretion intensity was lower than in cows grazing at LIMax (p ≤ 0.05). Strategic grazing management using the LI95% pre–grazing target increases N losses through both urine and feces; however, it reduces N excretion intensity of dairy cows by 9 %.
... In all feeding scenarios (S, M, and Var), high CP intake was observed. A larger supply of CP in the diet results in greater excretion of N [40]. In dairy cattle grazing native pastures, Sainz-Sánchez et al. [18] did not find differences in the productive response of low-production cows (11.9 kg/d) at two levels of CP supplementation (6 kg (high) and 4 kg (low) of concentrate per day). ...
... In dairy cattle grazing native pastures, Sainz-Sánchez et al. [18] did not find differences in the productive response of low-production cows (11.9 kg/d) at two levels of CP supplementation (6 kg (high) and 4 kg (low) of concentrate per day). Following protein supplementation, Danes et al. [40] did not observe an improvement in production, nutrient digestion, or microbial protein synthesis in grazing dairy cattle but did observe an effect on the concentrations of plasma urea nitrogen (PUN), nitrogen urea in milk (MUN), and N-NH 3 . These authors [40] highlighted that the protein content of grass in addition to an energy supplement was sufficient for fulfilling the nutritional requirements of dairy cows. ...
... Following protein supplementation, Danes et al. [40] did not observe an improvement in production, nutrient digestion, or microbial protein synthesis in grazing dairy cattle but did observe an effect on the concentrations of plasma urea nitrogen (PUN), nitrogen urea in milk (MUN), and N-NH 3 . These authors [40] highlighted that the protein content of grass in addition to an energy supplement was sufficient for fulfilling the nutritional requirements of dairy cows. Similar results were observed in medium-production cows (20 L/d −1 ) grazing on tropical gramineous plants containing 18.5% CP [40]. ...
In cattle, greenhouse gas (GHG) emissions and nutrient balance are influenced by factors such as diet composition, intake, and digestibility. This study evaluated CH4 emissions and surpluses of crude protein, using five simulated scenarios of supplementation in small-scale dairy systems (SSDS). In addition, two pasture managements (cut-and-carry versus grazing) and two varieties of legumes (red clover vs. white clover) were considered. The diets were tested considering similar milk yield and chemical composition; CH4 emission was estimated using Tier-2 methodology from the Intergovernmental Panel on Climate Change (IPCC), and the data were analyzed in a completely randomized 5 × 2 × 2 factorial design. Differences (p < 0.05) were found in predicted CH4 emissions per kg of milk produced (g kg−1 FCM 3.5%). The lowest predicted CH4 emissions were found for S3 and S4 as well as for pastures containing white clover. Lower dietary surpluses of CP (p < 0.05) were observed for the control diet (1320 g CP/d), followed by S5 (1793 g CP/d), compared with S2 (2175 g CP/d), as well as in cut-and-carry management with red clover. A significant correlation (p < 0.001) was observed between dry matter intake and CH4 emissions (g−1 and per kg of milk produced). It is concluded that the environmental impact of formulating diets from local inputs (S3 and S4) can be reduced by making them more efficient in terms of methane kg−1 of milk in SSDS.
... When grazing cool season forages, the ADG of dairy heifers can range from 0.84 to 1.18 kg/d without concentrate supplementation [5][6][7]. On the other hand, when warm-season grasses are managed intensively, NDF can be as low as 58% (%DM), and lignin as low as 2.63% (%DM; [8]). Additionally, the CP content is increased under this condition. ...
... Additionally, the CP content is increased under this condition. For example, [8] reported a value of 18% CP for elephant grass. ...
... 7 Crude protein. 8 Data estimated based on control animals https://doi.org/10.1371/journal.pone.0221651.t002 heifers using rotational grazing, irrigated and fertilized with 200 kg of N/ha/year and 150 kg of K 2 O/ha/year. ...
The literature lacks studies investigating the performance of supplemented replacement heifers grazing on intensively managed warm-season pasture. Our objective was to evaluate the effects of supplement composition (energetic or protein) on the performance, muscle development, thermogenisis, nutrient intake, and digestibility of replacement Holstein heifers grazing Mombaça grass. Eighteen Holstein heifers with an average age and initial body weight (BW) of 12.57 ± 2.54 mo and 218.76 ±47.6 kg, respectively, were submitted to a randomized block design, with six replicates on a rotational grazing system of Panicum maximum cv. Mombaça pasture. Treatments were: control (CON; mineral salt ad libitum); energy supplement (ENE; corn meal as supplement, 8% CP and 3.78 Mcal/kg DE); and protein supplement (PRO; corn and soybean meal, 25% CP and 3.66 Mcal/kg DE). Supplements were individually fed at 0.5% BW. The experiment lasted 120 days, subdivided into three periods. Titanium dioxide and indigestible neutral detergent fiber (iNDF) were used to estimate the intakes and digestibility of the nutrients. BW, wither height, thoracic circumference, body length, and ultrasound of ribeye fat thickness measurements were taken once per period. Body condition score (BCS) was assessed twice during the experiment. The MIXED procedure of SAS, including period as a repeated measure, was used and significance was declared at P ≤ 0.05. Dry matter intake (DMI), CP intake (CPI) and DE intake were greater in heifers fed PRO compared to CON and ENE. Heifers supplemented with ENE had the lowest DMI. Treatment affected pasture intake/BW; it was similar between PRO and CON heifers, and lower for the ENE treatment. A treatment × period interaction was observed for NDF intake (%BW), in which heifers fed PRO and CON had the greatest NDF intake and ENE had the lowest. The digestibility of DM was the greatest in PRO-supplemented heifers and the lowest in CON heifers. Heifers fed ENE had decreased CP digestibility compared to PRO and CON heifers. Average daily gain (ADG) and thoracic circumference gain were greatest in the PRO treatment. BCS was greater in PRO compared to CON and ENE heifers. Supplementing Holstein heifers at 0.5% BW using PRO supplementation resulted in better animal performance, primarily greater ADG, than feeding ENE or not supplementing (CON). In conclusion, our results indicate that dairy heifers should be fed a protein supplement when grazing intensively managed Mombaça grass pasture.
... Nutrient intake and apparent digestibility increase with an increase in dietary CP level [6]. Some literatures have shown that an increase in dietary protein level significantly increases blood urea-nitrogen (BUN) level [7], ruminal NH 3 -N concentration [8,9] and urinary N excretion [10] and decreases N utilisation efficiency [11]. Ruminal fermentation can be improved because cattle receiving diets containing high CP level show significantly higher bacterial population [6], microbial protein synthesis [7] and volatile fatty acid (VFA) concentration in rumen fluid [9,12] than cattle receiving diets containing low CP level. ...
... Ruminal fermentation can be improved because cattle receiving diets containing high CP level show significantly higher bacterial population [6], microbial protein synthesis [7] and volatile fatty acid (VFA) concentration in rumen fluid [9,12] than cattle receiving diets containing low CP level. Previous studies evaluating optimal dietary CP levels for cattle have provided varied results [11,13]. However, most of these studies have focused on mature dairy cows and finishing cattle. ...
... p<0.05; Figure 4). Danes et al [11] reported that low dietary CP level increased N utilisation efficiency. In cows fed total mixed ration containing 14.8%, 15.6%, and 16.4% CP, N utilisation efficiency decreased with an increase in dietary CP level [23]. ...
Objective:
This study investigated the effect of dietary crude protein (CP) supplementation on nutrient intake, nitrogen (N) utilisation, blood metabolites, ruminal fermentation and growth performance of young Holstein bulls.
Methods:
Twenty-one young bulls weighing 277 ± 11.2 kg were equally divided into three groups and were offered diets formulated with low CP [LCP; 10.21% CP and 4.22% rumen degradable protein (RDP)], medium CP (MCP; 12.35% CP and 5.17% RDP) and high CP (HCP; 14.24% CP and 6.03% RDP). Yellow corn silage was used as a unique forage source and was mixed with concentrate. This mixed feed was given ad libitum to the young bulls included in the study.
Results:
Results showed that CP intake, blood urea nitrogen, N intake, total N excretion and N balance increased linearly with an increase in dietary CP level (p<0.05). However, no significant difference was observed in nutrient digestibility among the bulls receiving the different diets. Ruminal pH (p<0.05) and ammonia nitrogen (NH3-N) concentration (p<0.01) were significantly higher in the bulls receiving the MCP and HCP diets than in those receiving the LCP diet. The bulls receiving the HCP diet showed significantly higher ruminal bacterial protein level, propionate, acetate and total volatile fatty acid (TVFA) concentrations than bulls receiving the LCP diet (p<0.05). Moreover, dietary CP level exerted a significant positive effect on the final body weight (BW), average daily gain (ADG) and G:F of the bulls (p<0.05).
Conclusion:
High dietary CP level is optimal for achieving maximum growth and high profitability without exerting a negative effect on the physiology of growing Holstein bulls.
... For cows producing 20 l/d of milk and grazing elephant grass as pasture (18.6% CP), Danes et al. (2013) studied three CP levels of concentrate (8.7%, 13.4% and 18.1% CP), and did not observe effect of CP concentrate on DMI, milk yield, and fat and crude. However, to meet the requirements of dairy cows for amino acids balancing RDP and RUP, the nitrogen sources, crude protein content, and ruminal carbohydrate digestibility may be considered in diet formulation. ...
... Therefore, in this study and the study of Danes et al. (2013), for cows with average milk production of 17- et al. (2007b) reported that the addition of urea (0; ...
... itrogen source associated with two dietary CP levels, low (142.07 to 142.29 g of CP/kg DM) or high (155.7 to 156.25 g of CP/kg DM), for cows fed sugarcane as forage. As a result,Jesus et al. (2012) found no effect of nitrogen source, CP content and interaction effect between them on milk yield, FCM, and daily production of protein, fat and lactose.Danes et al. (2013) studied the effect of three levels of dietary crude protein diet for cows grazing on elephant grass as pasture, and similar to the present study, there was no observed effect of dietary protein on milk yield and fat and protein daily production. ...
O objetivo do presente estudo foi avaliar o efeito de dois teores proteicos (PB) e duas fontes nitrogenadas na dieta de vacas leiteiras, utilizando cana-de-açúcar como forragem, sobre o consumo, digestibilidade aparente total, produção e composição do leite, e o balanço de nitrogênio. Doze vacas leiteiras Holandesas em estágio intermediário de lactação foram distribuídas em três quadrados contemporâneos, em um delineamento em quadrado latino 4 × 4, com arranjo fatorial de tratamentos 2 × 2, em períodos de 21 dias, onde os primeiros 14 dias foram destinados para a adaptação às dietas e os últimos sete para as coletas de dados e análises. As vacas foram alocadas em baias individuais em um sistema free-stall, e alimentadas com dietas totalmente misturada (TMR) “ad libitum” compostas por duas fontes nitrogenadas principais (farelo de algodão ou grão de soja crú integral) e dois níveis de proteína (130 g ou 148 g/kg de matéria seca- MS). No presente estudo, houve efeito de interação entre a fonte nitrogenada e o teor de PB sobre o consumo de MS (CMS). As vacas alimentadas com grão de soja crú integral tiveram maior CMS quando o teor de PB da dieta foi de 130 g CP/kg MS, enquanto que as vacas alimentadas com farelo de algodão apresentaram maior CMS quando o teor de PB da dieta foi de 148 g PB/kg MS. Resultado semelhante ao CMS foi observado para o consumo de matéria orgânica, enquanto que não houve efeito de interação entre fonte nitrogenada e teor de PB sobre o consumo dos demais nutrientes dietéticos. A digestibilidade aparente total da FDN foi maior quando grão de soja crú integral foi utilizado como principal fonte nitrogenada da dieta; enquanto que a digestibilidade da PB não foi alterada pelas fontes nitrogenadas. Apesar de haver alterações no CMS e na digestibilidade aparente total, no presente estudo, não houve efeito de teor de PB e fonte nitrogenada sobre a produção de leite. Como conclusão, o uso de baixo teor dietético de PB (130 g PB/kg de MS) não altera o desempenho produtivo de vacas leiteiras e pode reduzir os custos da dieta, enquanto que a escolha entre grão de soja cru integral e farelo de algodão como principais fontes nitrogenadas da dieta pode depender apenas da disponibilidade e custo, uma vez que ambos ingredientes apresentam desempenhos semelhantes.
... This increased the ammonia production in the rumen fluid and its absorption by the rumen epithelium (Kozloski, 2011), resulting in higher blood urea and MUN levels (González and Campos, 2018). Indeed, ruminal ammonia, blood urea nitrogen (BUN), and MUN are associated (Lee et al., 2012;Danes et al., 2013;Alves et al., 2020), and the latter can be used to evaluate whether a diet is adequate in RDP relative to the energy level (Schwab and Broderick, 2017;González and Campos, 2018). High MUN levels associated with increased RDP intake from concentrate feed have also been reported for Holstein × Zebu cows fed elephant grass silage (Gomes et al., 2016) and for Holstein × Jersey cows grazing on elephant grass pasture (Danes et al., 2013;Chagas et al., 2021). ...
... Indeed, ruminal ammonia, blood urea nitrogen (BUN), and MUN are associated (Lee et al., 2012;Danes et al., 2013;Alves et al., 2020), and the latter can be used to evaluate whether a diet is adequate in RDP relative to the energy level (Schwab and Broderick, 2017;González and Campos, 2018). High MUN levels associated with increased RDP intake from concentrate feed have also been reported for Holstein × Zebu cows fed elephant grass silage (Gomes et al., 2016) and for Holstein × Jersey cows grazing on elephant grass pasture (Danes et al., 2013;Chagas et al., 2021). Despite the highest value obtained in the PM group, the MUN levels remained within the normal range of 10-16 mg/dL (Jonker et al., 1998) for all protein sources. ...
The purpose of this study was to evaluate the effects of total replacement of soybean meal (SBM) with three alternative protein sources in the concentrate supplement on performance, feed efficiency, milk composition, and diurnal ingestive behavior of Holstein × Gyr cows under an intensive system of grazing on tropical pasture. Twelve cows with 512 ± 61 kg of BW (mean ± standard deviation), 20.4 ± 4.1 kg/d of milk yield, and 86 ± 40 days in milk were distributed in a triplicated 4 × 4 Latin square design. The treatments consisted of four concentrate supplements formulated with SBM (Control), cottonseed meal (CSM), peanut meal (PM), or sunflower meal (SFM). The animals were kept in intensive rotational grazing (n = 24 paddocks) on Tanzania grass (Panicum maximum syn. Megathyrsus maximus) pasture, with 1 day of occupation per paddock and a stocking rate of 4.3 AU/ha. The daily amount of concentrate supplement offered to the cows was 1 kg DM of concentrate per 3 kg of milk produced. Fat-corrected milk yield (FCM) for the SBM group (21.1 kg/d) was similar to that of the other groups (21.5 kg/d on average); however, milk fat content and milk urea nitrogen were lower in the SBM group (36 g/kg and 12.6 mg/dL) than in the PM group (38.4 g/kg and 14.2 mg/dL). The protein source did not affect the intakes of DM (17.14 kg/d on average) and forage (9.66 kg DM/d on average). However, cows fed CSM had a lower concentrate supplement intake compared to those fed PM (7.11 vs. 7.78 kg DM/d). The lowest and the highest ether extract intake levels were observed in cows fed with SBM (0.31 kg/d) and CSM (0.39 kg/d). No effect of the protein source was detected on the time spent on grazing, rumination, and idleness, with mean values of 4.73, 2.01, and 5.26 hours within a 12-hour observation period (06:00–18:00 h). Soybean meal can be replaced with CSM, PM, or SFM in the concentrate supplement without affecting the FCM, feed intake, feed efficiency, and diurnal ingestive behavior of lactating Holstein × Gyr cows in an intensive tropical grazing system. The replacement of SBM with PM is recommended since the latter promotes the best results in terms of milk fat content.
... Such pattern was observed in our study since the increase in the concentration of nitrogen compounds in the diet as well as the low assimilation of excess N in microbial protein caused an increase of N-NH 3 in the ruminal fluid. Danes et al. (2013) evaluated the ruminal parameters of cows kept on pasture of Pennisetum purpureum with 18.5% of CP supplemented with three different levels of protein in the concentrate. These authors observed increasing concentrations of ammonia nitrogen as the CP content increased. ...
... These authors observed increasing concentrations of ammonia nitrogen as the CP content increased. Our findings corroborate those published by Danes et al. (2013). ...
The present study aimed to evaluate the degradation dynamics of high-quality tropical forage according to the levels of nitrogen supplementation. In this study, 4 rumen-fistulated cows with a body weight of 653 ± 47 kg were used. These animals were distributed in a 4 × 4 Latin square experimental design. Cows were kept under a grazing regime in an area formed by Panicum maximum Jacq. cv. Tanzania. These animals received 4 levels of crude protein (CP) in the supplements (122, 142, 162, and 180 g/kg of CP in DM). The degradability of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) was determined by in situ incubation of forage samples at 0, 6, 12, 24, 48, 72, 96, and 120 h. Both the concentration of ammonia nitrogen (NH3-N) and the microbial protein synthesis were affected by CP levels of the supplements (P < 0.05). There was a significant difference (P < 0.05) for fraction b, potential degradability, and effective degradability of DM and NDF, and for the c degradation rate of CP of Tanzania grass which had the highest values at 122 g/kg of CP. Overall, the greatest degradation of nutrients from Tanzania grass occurred in the diet with 122 g/kg of CP and 604 g/kg of NFC in dairy cattle supplements that resulted in the highest rates of nitrogen utilization by rumen microbes.
... The rate was established based on milk yield at the beginning of each sampling period (Danes et al., 2013 ...
... The rate was established based on milk yield at the beginning of each period (Danes et al., 2013). The concentrate meal was composed of fine ground corn (80%), soybean meal (15%) and mineral (5%), with chemical composition as following: 86.8% of DM, 9.4% of ash, 13.6% of CP, 13.2% of NDF, 3.4% of ADF, 3.9% of EE and 59.9% of NFC. ...
Pasture-based systems are important milk suppliers to dairy industry and thereby will play relevant role to support the growing demand for food. However, this additional milk supply must be obtained through higher yields resulting from intensification of existing farming systems through strategies environmentally friendly and economically profitable towards sustainable intensification. The central hypothesis of this study was that simple grazing management strategies can improve the efficiency while reduce the key environmental issues of tropical pasture-based dairy systems. Two experiments were carried out on a rainfed and non-irrigated elephant grass (Pennisetum purpureum Schum. cv. Cameroon) pasture in Piracicaba, SP, Brazil. The objective of the first experiment was to investigate the influence of two pre-grazing targets (95% and maximum canopy light interception during pasture regrowth; LI95% and LIMAX, respectively) on sward structure and herbage nutritive value, dry matter intake (DMI), milk yield, stocking rate, enteric methane (CH4) emissions by Holstein × Jersey dairy cows, and nitrous oxide fluxes from the soil. Results indicated that pre-grazing canopy height was greater for LIMAX (≈135 cm) than LI95% (≈100 cm) and can be used as a reliable field guide for monitoring sward structure. Grazing management based on the LI95% target improved herbage nutritive value and grazing efficiency, allowing greater DMI, milk yield and stocking rate by dairy cows. Daily enteric CH4 emission was not affected; however, cows grazing elephant grass at LI95% were more efficient and emitted 21% less CH4/kg of milk yield and 18% less CH4/kg of DMI. The 51% increase in milk yield per hectare overcame the 29% increase in enteric CH4 emissions per hectare for the LI95% target. Nitrous oxide fluxes were not affected by pre-grazing targets. Overall, strategic grazing management is an environmentally friendly practice that improves the use efficiency of allocated resources through optimization of processes involving plant, ruminant and their interface, and enhances milk production efficiency of tropical pasture-based systems. Once the ideal pre-grazing target was established during he first experiment (LI95%), the second step consisted of a refinement of the first phase. The second objective was to describe and measure the influence of two timings of new paddock allocation to cows (AM and PM) on herbage chemical composition and DMI, milk yield, milk compostion, and enteric CH4 emissions of Holstein × Jersey dairy cows. Results supported the general understanding of diurnal variation in herbage chemical composition towards greater concentrations of dry matter and non-fibrous carbohydrates, and lower concentration of fiber components in the afternoon herbage. However, the higher nutritive value of the afternoon herbage did not result in increasead DMI and milk yield, or decreased intensity of CH4 emission by dairy cows. Our findings also indicate that new paddock allocation in the afternoon can be a simple and useful grazing strategy that results in greater N partitioning to protein yield, and lower excretion of urea N in milk. The association of LI95% pre-grazing target and PM allocation could bring economic, productive and environmental benefits towards sustainable intensification of tropical pasture-based systems.
... Se formó una muestra de excremento compuesta a partir de alícuotas diarias, y el contenido de Cr se determinó por espectroscopia de absorción atómica (13) . La producción de excremento se obtuvo con la fórmula: [(g de Cr dosificados)*(Tasa de recuperación)] / [Cr] en excremento; se supuso una tasa de recuperación del 82.5 %, con base en la información presentada por Danes et al (14) . from the pasture by the grazing cow, which is easily audible (11) . ...
... A composite feces sample was made from daily aliquots and its Cr content determined by atomic absorption spectroscopy (13) . Production of feces was obtained by the formula: [(dosed g of Cr) * (recovery rate)] / [Cr] in feces; a recovery rate of 82.5 % was assumed, based on the information published by Danes et al (14) . The DM digestibility of ingested grass (extrusa) was estimated using the in situ method for 48 h of ruminal incubation (15) of extrusa esophageal samples, which were introduced as dried and ground (Wiley Mill # 4 sieve 1 mm) in triplicate into the rumen. ...
Se introdujo la leguminosa Arachis pintoi CIAT 17434 (AP) en una pastura de gramas nativas, para estudiar su efecto sobre la conducta de ingestión del animal al pastar, en la época lluviosa del trópico húmedo del estado de Veracruz. Los tratamientos fueron gramas nativas (PN, testigo) y AP asociado a gramas nativas (PNA). La rotación fue 1 día de pastoreo/20 días de recuperación con carga de 3.2 vacas F1 (Holstein x Cebú)/ha. Las diferencias se probaron a P<0.05, presentándose primero las medias ± error estandar de PNA y luego de PN. Hubo diferencias entre tratamientos en cantidad de materia seca (MS) presente antes del pastoreo (4,225 ± 212 vs 3,314 ± 212 kg/ha), así como en proteína cruda (15.1 ± 0.45 vs 10.6 ± 0.5 %) y materia orgánica (MO) digestible (67.65 ± 1.7 vs 64.1 ± 2.4 %) de la extrusa esofágica. El tiempo de pastoreo (367 ± 11 vs 380 ± 11 min/24 h) fue similar entre tratamientos y el de rumia diferente (291 ± 8 vs 379 ± 8 min/24 h). No hubo diferencias en consumo de MO calculado por Cr-indigestibilidad in situ (2.09 ± 0.11 vs 2.16 ± 0.11 kg MO/100 kg PV), pero por comportamiento ingestivo, si las hubo (1.54 ± 0.12 vs 2.02 ± 0.12). La producción diaria (kg/vaca) de leche ordeñada (6.8 ± 0.4 vs 6.1 ± 0.4) y consumida por el becerro (4.4 ± 0.4 vs 3.8 ± 0.5) fueron similares, pero la producción total fue diferente (9.0 ± 0.6 vs 7.2 ± 0.6 kg/animal/ día).
... The starch digestibility in dairy cows improves with maize diets, with mean particle size. However, although milk production and protein increases, the fat production in the milk is reduced (Danes et al. 2013). Protein supplements are an essential component of feed rations for cows of high dairy yield (Horký 2014). ...
... La digestibilidad del almidón en las vacas lecheras mejora con las dietas de maíz, con tamaño de partícula media. Sin embargo, aunque se incrementa la producción de leche y proteína, la producción de grasa en la leche se reduce (Danes et al. 2013). Los suplementos de proteínas representan un componente indispensable de las raciones de alimento para vacas de alto rendimiento lechero (Horký 2014). ...
In order to determine the effect of ruminal degradation of maize crude protein obtained with two levels of nitrogen (300 and 400 kg ha⁻¹) and two irrigation techniques (gravity and drip), dacron bags (10 × 18 cm) which contained 5 g of maize were used. By introducing a cannula, the bags were inoculated for 0, 3, 6, 12 and 24 h in the rumen of four heifers. A completely randomized design was applied with factorial arrangement 2×2 of the treatments (nitrogen and irrigation technique).There were not statistical differences between the interactions of the variables under study (P < 0.05).However, drip irrigation vs gravity (8.72 vs 8.05%) and fertilization with 400 vs 300 kg de N ha-1 (8.52 vs. 8.25 %) increased (P ≤ 0.05) the crude protein content of the grain. The treatments did not affect (P ≥ 0.21) the PC solubility (19.4 plusmn; 2.85 %).The ruminal degradation of the maize CP in the different incubation times did not change (P ≥ 0.20) by the maize grain obtained by means of irrigation technique or N levels used in maize production. The ruminal degradation rate of CP (0.10 plusmn; 0.03) did not change (P ≥ 0.13) by the treatments. The percentage of crude protein effectively degraded in the rumen (42.14 plusmn; 2.83 %) was similar (P ≥ 0.48) between treatments. Although the schemes of nitrogen levels or irrigation technique can modify the crude protein content in the maize grain, this did not influence on the characteristics of ruminal degradation of its crude protein.
... Se formó una muestra de excremento compuesta a partir de alícuotas diarias, y el contenido de Cr se determinó por espectroscopia de absorción atómica (13) . La producción de excremento se obtuvo con la fórmula: [(g de Cr dosificados)*(Tasa de recuperación)] / [Cr] en excremento; se supuso una tasa de recuperación del 82.5 %, con base en la información presentada por Danes et al (14) . from the pasture by the grazing cow, which is easily audible (11) . ...
... A composite feces sample was made from daily aliquots and its Cr content determined by atomic absorption spectroscopy (13) . Production of feces was obtained by the formula: [(dosed g of Cr) * (recovery rate)] / [Cr] in feces; a recovery rate of 82.5 % was assumed, based on the information published by Danes et al (14) . The DM digestibility of ingested grass (extrusa) was estimated using the in situ method for 48 h of ruminal incubation (15) of extrusa esophageal samples, which were introduced as dried and ground (Wiley Mill # 4 sieve 1 mm) in triplicate into the rumen. ...
A study was conducted in the humid tropics of the state of Veracruz during the rainy season, in order to determine the effect of introducing the legume Arachis pintoi CIAT 17434 (AP) into a native pasture, upon the grazing ingestive behavior of cows. Treatments were the native pasture (PN, control) and PN associated with AP (PNA). A 1 d grazing/20 d recovery rotation and a stocking rate of 3.2 F1 (Holstein x Cebu) cows/ha were used. Significance was set at P<0.05. Means +/- standard error are presented for PNA first and then for PN. There were differences in standing dry matter (kg/ha) before grazing (4,225 +/- 212 vs 3,314 +/- 212 kg/ha), and crude protein (15.1 +/- 0.4 vs 10.6 +/- 0.5) and digestible organic matter (OM) (67.6 +/- 1.7 vs 64.1 +/- 2.0 %) of oesophageal extrusa. Grazing time (min/24 h) was similar between treatments (367 +/- 11 vs 380 +/- 11), but ruminating time was not (291 +/- 8 vs 379 +/- 8). OM intake (kg OM/100 kg LW) calculated by Crin situ digestibility was similar between treatments (2.09 +/- 0.11 vs 2.16 +/- 0.11), while intakes calculated by ingestive behavior were different (1.54 +/- 0.12 vs 2.02 +/- 0.12). Saleable milk yield and milk intake by calf (kg/animal/d) were similar between treatments: 6.8 +/- 0.4 vs 6.1 +/- 0.4, and 4.4 +/- 0.4 vs 3.8 +/- 0.5, but total milk yield was different: 9.0 +/- 0.6 vs 7.2 +/- 0.6.
... Napier, being a C 4 grass, requires a high amount of fertiliser to achieve high yields. It requires 600 kg N/ha (Lotero et al., 1969) to 2,223 kg N/ha (Vicente-Chandler et al., 1959) to produce from 50 to Sources: Ferraris, 1980;Brown et al., 1988;Anindo and Potter, 1994;Aroeira et al., 1999;Filho et al., 2000;Huque et al., 2001;Gwayumba et al., 2002;Islam et al., 2003;Aganga et al., 2005;Goorahoo et al., 2005;Chen et al., 2006;Castillo et al., 2010;Das et al., 2010;Bureenok et al., 2012;Danes et al., 2013;Ferreira et al., 2013;Halim et al., 2013;Gomide et al., 2015;Amin et al., 2016;Aswanimiyuni et al., 2018;Garcez et al., 2018;Gusmao et al., 2018;Habte et al., 2022;Kaitho and Kariuki, 1998;Kariuki et al., 1998;Kariuki et al., 1999;Kozloski et al., 2003;Kozloski et al., 2005;Khairani et al., 2013;Knoll et al., 2013;Kabirizi et al., 2015;Khota et al., 2018;Lounglowan et al., 2014;Manyawu et al., 2003a;Manyawu et al., 2003b;Manyawu et al., 2003c;Magalhães et al., 2010;Muinga et al., 1992;Muinga et al., 1993;Nsahlai et al., 2000;Muia et al., 2001a;Muia et al., 2001b;Muyekho et al., 2015;Parsons et al., 2012;Pieterse and Rethman, 2002;Rahman et al., 2010;Rahman et al., 2013;Rahman et al., 2013;Ruiz et al., 1992;Rao et al., 1993;Schank et al., 1993;Sarwar et al., 1999;Rengsirikul et al., 2013;Rahman et al., 2014a;Ramadhan et al., 2015;Roy et al., 2016;Schneider et al., 2018;Sileshi et al., 1996;Shem et al., 2003;Sidhu et al., 2011;Skerman and Riveros, 1990;Tamada et al., 1999;Tessema and Baars, 2004;Tessema, 2008;Vicente-Chandler et al., 1959;Woodard and Prine, 1993;Vieira et al., 1997;Wijitphan et al., 2009;Tessema et al., 2010;Yammeun-art et al., 2017;Yokota et al., 1998;Zhang and Kumal, 2000;Zewdu et al., 2002;Zhang et al., 2010. (Table 2). ...
... Napier, being a C 4 grass, requires a high amount of fertiliser to achieve high yields. It requires 600 kg N/ha (Lotero et al., 1969) to 2,223 kg N/ha (Vicente-Chandler et al., 1959) to produce from 50 to Sources: Ferraris, 1980;Brown et al., 1988;Anindo and Potter, 1994;Aroeira et al., 1999;Filho et al., 2000;Huque et al., 2001;Gwayumba et al., 2002;Islam et al., 2003;Aganga et al., 2005;Goorahoo et al., 2005;Chen et al., 2006;Castillo et al., 2010;Das et al., 2010;Bureenok et al., 2012;Danes et al., 2013;Ferreira et al., 2013;Halim et al., 2013;Gomide et al., 2015;Amin et al., 2016;Aswanimiyuni et al., 2018;Garcez et al., 2018;Gusmao et al., 2018;Habte et al., 2022;Kaitho and Kariuki, 1998;Kariuki et al., 1998;Kariuki et al., 1999;Kozloski et al., 2003;Kozloski et al., 2005;Khairani et al., 2013;Knoll et al., 2013;Kabirizi et al., 2015;Khota et al., 2018;Lounglowan et al., 2014;Manyawu et al., 2003a;Manyawu et al., 2003b;Manyawu et al., 2003c;Magalhães et al., 2010;Muinga et al., 1992;Muinga et al., 1993;Nsahlai et al., 2000;Muia et al., 2001a;Muia et al., 2001b;Muyekho et al., 2015;Parsons et al., 2012;Pieterse and Rethman, 2002;Rahman et al., 2010;Rahman et al., 2013;Rahman et al., 2013;Ruiz et al., 1992;Rao et al., 1993;Schank et al., 1993;Sarwar et al., 1999;Rengsirikul et al., 2013;Rahman et al., 2014a;Ramadhan et al., 2015;Roy et al., 2016;Schneider et al., 2018;Sileshi et al., 1996;Shem et al., 2003;Sidhu et al., 2011;Skerman and Riveros, 1990;Tamada et al., 1999;Tessema and Baars, 2004;Tessema, 2008;Vicente-Chandler et al., 1959;Woodard and Prine, 1993;Vieira et al., 1997;Wijitphan et al., 2009;Tessema et al., 2010;Yammeun-art et al., 2017;Yokota et al., 1998;Zhang and Kumal, 2000;Zewdu et al., 2002;Zhang et al., 2010. (Table 2). ...
... Napier, being a C 4 grass, requires a high amount of fertiliser to achieve high yields. It requires 600 kg N/ha (Lotero et al., 1969) to 2,223 kg N/ha (Vicente-Chandler et al., 1959) to produce from 50 to Sources: Ferraris, 1980;Brown et al., 1988;Anindo and Potter, 1994;Aroeira et al., 1999;Filho et al., 2000;Huque et al., 2001;Gwayumba et al., 2002;Islam et al., 2003;Aganga et al., 2005;Goorahoo et al., 2005;Chen et al., 2006;Castillo et al., 2010;Das et al., 2010;Bureenok et al., 2012;Danes et al., 2013;Ferreira et al., 2013;Halim et al., 2013;Gomide et al., 2015;Amin et al., 2016;Aswanimiyuni et al., 2018;Garcez et al., 2018;Gusmao et al., 2018;Habte et al., 2022;Kaitho and Kariuki, 1998;Kariuki et al., 1998;Kariuki et al., 1999;Kozloski et al., 2003;Kozloski et al., 2005;Khairani et al., 2013;Knoll et al., 2013;Kabirizi et al., 2015;Khota et al., 2018;Lounglowan et al., 2014;Manyawu et al., 2003a;Manyawu et al., 2003b;Manyawu et al., 2003c;Magalhães et al., 2010;Muinga et al., 1992;Muinga et al., 1993;Nsahlai et al., 2000;Muia et al., 2001a;Muia et al., 2001b;Muyekho et al., 2015;Parsons et al., 2012;Pieterse and Rethman, 2002;Rahman et al., 2010;Rahman et al., 2013;Rahman et al., 2013;Ruiz et al., 1992;Rao et al., 1993;Schank et al., 1993;Sarwar et al., 1999;Rengsirikul et al., 2013;Rahman et al., 2014a;Ramadhan et al., 2015;Roy et al., 2016;Schneider et al., 2018;Sileshi et al., 1996;Shem et al., 2003;Sidhu et al., 2011;Skerman and Riveros, 1990;Tamada et al., 1999;Tessema and Baars, 2004;Tessema, 2008;Vicente-Chandler et al., 1959;Woodard and Prine, 1993;Vieira et al., 1997;Wijitphan et al., 2009;Tessema et al., 2010;Yammeun-art et al., 2017;Yokota et al., 1998;Zhang and Kumal, 2000;Zewdu et al., 2002;Zhang et al., 2010. (Table 2). ...
... Napier, being a C 4 grass, requires a high amount of fertiliser to achieve high yields. It requires 600 kg N/ha (Lotero et al., 1969) to 2,223 kg N/ha (Vicente-Chandler et al., 1959) to produce from 50 to Sources: Ferraris, 1980;Brown et al., 1988;Anindo and Potter, 1994;Aroeira et al., 1999;Filho et al., 2000;Huque et al., 2001;Gwayumba et al., 2002;Islam et al., 2003;Aganga et al., 2005;Goorahoo et al., 2005;Chen et al., 2006;Castillo et al., 2010;Das et al., 2010;Bureenok et al., 2012;Danes et al., 2013;Ferreira et al., 2013;Halim et al., 2013;Gomide et al., 2015;Amin et al., 2016;Aswanimiyuni et al., 2018;Garcez et al., 2018;Gusmao et al., 2018;Habte et al., 2022;Kaitho and Kariuki, 1998;Kariuki et al., 1998;Kariuki et al., 1999;Kozloski et al., 2003;Kozloski et al., 2005;Khairani et al., 2013;Knoll et al., 2013;Kabirizi et al., 2015;Khota et al., 2018;Lounglowan et al., 2014;Manyawu et al., 2003a;Manyawu et al., 2003b;Manyawu et al., 2003c;Magalhães et al., 2010;Muinga et al., 1992;Muinga et al., 1993;Nsahlai et al., 2000;Muia et al., 2001a;Muia et al., 2001b;Muyekho et al., 2015;Parsons et al., 2012;Pieterse and Rethman, 2002;Rahman et al., 2010;Rahman et al., 2013;Rahman et al., 2013;Ruiz et al., 1992;Rao et al., 1993;Schank et al., 1993;Sarwar et al., 1999;Rengsirikul et al., 2013;Rahman et al., 2014a;Ramadhan et al., 2015;Roy et al., 2016;Schneider et al., 2018;Sileshi et al., 1996;Shem et al., 2003;Sidhu et al., 2011;Skerman and Riveros, 1990;Tamada et al., 1999;Tessema and Baars, 2004;Tessema, 2008;Vicente-Chandler et al., 1959;Woodard and Prine, 1993;Vieira et al., 1997;Wijitphan et al., 2009;Tessema et al., 2010;Yammeun-art et al., 2017;Yokota et al., 1998;Zhang and Kumal, 2000;Zewdu et al., 2002;Zhang et al., 2010. (Table 2). ...
Napier grass ( Pennisetum purpureum Schumach) comprises up to 80% of the cattle diet in many tropical and subtropical regions and is used primarily by smallholder farmers. Despite the grass’s high yield, resulting animal productivity from this grass is low. One of the key reasons for the low animal productivity of Napier grass is its low nutritive value under current management. Taken together, previous work has shown the current yield, crude protein (CP), and metabolisable energy (ME) of Napier grass to be 26 t dry matter (DM)/ha/year, 96 g/kg DM, and 8.7 MJ/kg DM, respectively, ranging from 2 to 86 t DM/ha/year, 9 to 257 g CP/kg DM, and 5.9 to 10.8 MJ ME/kg DM, respectively, suggesting an opportunity for significant improvement on both yield and nutritive value of this grass. The DM yield and nutritive value of this grass are inversely related, indicating a trade-off between yield and quality; however, this trade-off could be minimised by increasing sowing density and harvesting frequency. Available literature shows that this simple management strategy of increasing sowing density (50 cm × 40 cm) and harvesting frequency (11–12 harvests/year) provides 71 t DM/ha with 135 g/kg DM CP and 10.8 MJ ME/kg DM. This quality of Napier grass has the potential to increase both milk and meat production substantially in the tropics and subtropics, and the farmers will likely find this simple management acceptable due to the high yield obtained through this management. However, there is a paucity of work in this field. Therefore, management strategies to improve the nutritive value of Napier grass are required to increase milk and meat production in the tropics and subtropics and in doing so improve the food security of more than half of the global population living in these regions.
... Thus, despite the higher total economic costs for INT and SIS, the higher yield production would dilute the total economic cost and increase revenue in turn. In fact, high-grain diets have more energy and protein levels that support milk productivity and increase milk solids content [65], but the use of high-grain diets can increase feeding costs, as they tend to be more expensive than forage-rich diets [66]. If dairy cows fed a high-grain diet do not have the genetic ability to express this feed increment in litres of milk produced, this higher cost for feed will be converted into an increase in nutrient excretion or average daily gain [67]. ...
This study aimed to evaluate the sustainability of integrated dairy–crop production systems by employing emergy and economic theory perspectives, and to identify strategies to improve the intensification of dairy production systems. A case study of a small Brazilian dairy production system (PROP) was created to assess dairy herd feed exchanges as a sustainability pathway. Three scenarios were proposed for the examination of a dairy production system: extensive (EXT); semi-intensive (SIS); and intensive (INT). The Interlink Decision Making Index (IDMI) was used to compare sustainability among them. The PROP demonstrated higher environmental performance than the other scenarios (ESI = 1.30, 0.65, 0.95, and 0.71, for PROP, INT, SIS, and EXT, respectively); however, PROP’s profitability was 1.6 times lower than that of SIS and INT, although PROP’s profitability was higher than that of the EXT scenario. Notably, the IDMI identified the SIS scenario as having the best sustainability among those studied. We concluded that the consideration of the energy contribution for feed ingredients yields a more equitable evaluation of environmental performance in integrated dairy–crop production systems, which leads us to propose the following suggestions: (i) target higher profit performance by changing extensive dairy systems to semi-intensive systems that utilize feed ingredients produced at the farm, and (ii) promote higher environmental performance by transforming intensive dairy systems to semi-intensive systems that are directed more toward maintaining environmental factors. In our view, public policies should focus on bonifications that upgrade dairy systems to promote and utilize best practices for dairy–crop integration.
... There were conflicting results about feeding a high-protein diet to the dairy cows. Some researchers stated that more dietary protein will increase the total milk production and 4% fat-corrected milk (27), while others did not detect any significant effect (26,28). The physiological state of animals is the main factor providing high efficiency of obtaining high-quality milk, healthy offspring, and more longevity of cows. ...
This study investigated the productive traits and some blood biochemical parameters of high-yielding Ayrshire dairy cows fed at different levels of Agro-Matic@LLC NGO, Russia (Agro-Matic (AM)) protein concentrate. A total of 45 high-yielding Ayrshire cows were selected and divided into three groups, each 15. The control group (0AM) fed the basal ration, while group two (1AM) and group three (2AM) fed a basal ration by replacing sunflower cake with different levels of AM (1 and 1.5 kg/head/day), respectively. Milk and blood samples were collected. The current results revealed that the ratio of rumen undegradable protein to rumen degradable protein during the period of lactation was significantly higher in the 1AM and 2AM compared with 0AM and represented (55.04, 62.14, and 41.73%), respectively. The 1AM had a beneficial effect on the digestibility of crude protein. Daily and whole fat-corrected milk (FCM 4 %) was significantly increased by 3 kg/day and 987 kg/entire lactation in 2AM when compared with 0AM, respectively. Blood total protein was significantly higher in the 1AM group (86.9 vs. 77.8 g/l) than the 0AM, while AM decreased urea concentration. Consequently, the inclusions of AM protein concentrate have a positive impact on increasing milk production and optimizing the rations in terms of the amount of non-digestible protein and the economic efficiency of milk production.
... The lactating cow's protein nutrition has great relevance due to the direct influence on animal performance, as well as on the food cost (Danés et al. 2013;Paiva et al. 2013). Thus, dietary protein is essential for both the maintenance of metabolic processes to support milk production (Silva et al. 2016) and for the production systems profitability as it is an expensive nutrient in the cow's diet. ...
The objective of this study was to evaluate the effects of replacing soybean meal with peanut meal on milk production, chemical and fatty acid composition, nutritional quality indicators of the lipid fraction, and the economic viability of the diets. Twelve crossbred cows in the initial lactation third, with a bodyweight of 545 ± 37 kg and average milk production of 28 kg/day of milk were distributed in a 4 × 4, triple Latin square design. The treatments consisted of diets with substitution levels of soybean meal for peanut meal (0; 330; 670; and 1000 g/kg in DM). The peanut meal inclusion to replace soybean meal in the diets provided a decreasing linear effect for the protein (P = 0.02) and casein (P = 0.01) concentration in milk. Milk production, total solids concentration, feed efficiency, fatty acid composition, and nutritional quality indicators of the milk lipid fraction were not influenced by the substitution levels. The diet cost per kg DM decreased due to the peanut meal inclusion as a protein source. The partial or total substitution of soybean meal for peanut meal in the feedlot cows diet reduces the cost of feed, without affecting milk production and total solids yield.
... However, the results of Barkah et al. (2017) stated that the use of NSM with levels of 10 and 20% in the ration significantly increased Blood Urea Nitrogen (BUN) levels. High levels of BUN indicate that NSM addition in feed increasee protein degradation in the rumen which can lead to inefficient of protein utilization due to excessive degradation of protein before it is used and absorbed in intestines.Increased levels of dietary protein significantly increased BUN levels (Norrapoke et al., 2012), rumen NH3-N concentration (Abadi et al., 2015), urinary N excretion (Leonardi et al., 2003) and decreased the efficiency of N utilization (Danes et al., 2013). It will causing economic loss, adverse environmental effects and possibly some metabolic diseases (Nocek, 1997). ...
... ruminal acidosis), which affects the animals' performance. Thus, the rational supply of protein supplements is essential to enable supplementation, requiring the development of strategies to maximize the use of the supplement and forage intake (Danes et al., 2013). In this context, the objective of this study was to evaluate different strategies of protein supplementation (nutritional plans) on the productive performance and milk composition of F1 Holstein x Zebu cows kept in deferred pasture of brachiaria grass. ...
The objective of this study was to evaluate different supplementation strategies concentrated to F1 Holstein x Zebu lactating cows managed in deferred signal grass pasture on the yield and composition of milk and body weight gain. Thirty six F1 Holstein x Zebu cows with an average lactation period of 267 ± 10 days, mean body weight of 548 ± 19kg were used following a completely randomized design in a 4 x 5 factorial scheme, being four feeding strategies and five days under evaluation. The treatments consisted of four nutritional strategies: deferred pasture as a source of roughage without supplementation (PDSS); deferred pasture as a source of roughage with protein supplement offer (PDCS); deferred pasture supplemented with 15 kilos of corn silage (natural base) + 1,200 grams of protein supplement (PDSP) and corn silage (ad libitum) + 700 grams of protein supplement (SMP). There was no interaction (P> 0.05) between the nutritional plans and days under evaluation for any of the variables. It was found that cows fed SMP showed milk production 26.06% higher than the other nutritional plans (mean of 11.46kg/day). F1 Holstein/Zebu cows handled in deferred pasture in a traditional way supplemented with protein maintains milk yield.
... Tropical pastures have a higher potential for forage yield accumulation (Santos et al., 2014) and recent rotational grazing strategies based on 95% light interception has considerably improved forage quality and animal performance compared with the traditional grazing approach (fixed days) (Congio et al., 2018). However, this grazing management strategy is not enough to meet the energy requirements of grazing dairy cows (Danes et al., 2013), mainly because tropical pastures have high fiber content and lower particle fragility, which negatively impacts animal feed intake and consequently performance (Moore and Mott, 1973;Allen, 1996). Therefore, the use of feeding systems combining grazing and the addition of high energy concentrates is required. ...
The use of grazing systems for milk production is widely used globally because it is a lower-cost feeding system. However, under tropical conditions, the energy content of pastures became is a limitation to improve animal performance and efficiency while reducing the environmental impact. The objective of our study was to evaluate the impact of supplying different dietary sources of energy to lactating dairy cows grazing tropical pastures on the recovery of human-edible (HE) nutrients in milk and the environmental impact. Two experiments were conducted simultaneously. In experiment 1, forty early lactating dairy cows were used in a randomized block design. In experiment 2, four late-lactating rumen-cannulated dairy cows were used in a 4 × 4 Latin Square design. All cows had free access to pasture and treatments were applied individually as a concentrate supplement. Treatments were flint corn grain-processing method either as fine ground (FGC) or steam-flaked (SFC) associated with Ca salts of palm fatty acids supplementation either not supplemented (CON) or supplemented (CSPO). We observed that feeding cows with SFC markedly reduced urinary nitrogen excretion by 43%, and improved milk nitrogen efficiency by 17% when compared with FGC. Additionally, we also observed that feeding supplemental fat improved milk nitrogen efficiency by 17% compared with cows receiving CON diets. A tendency for decreased methane (CH 4 ) per unit of milk (−31%), CH 4 per unit of milk energy output (−29%), and CH 4 per unit of milk protein output (−31%) was observed when CSPO was fed compared with CON. Additionally, SFC diets increased HE recovery of indispensable amino acids by 7–9% when compared with FGC diets, whereas feeding supplemental fat improved HE recovery of indispensable amino acids by 17–19% compared with CON. Altogether, this study increased our understanding of how manipulating energy sources in the dairy cow diet under tropical grazing conditions can benefit HE nutrient recovery and reduce nutrient excretion.
... Regardless of SC, the high NH 3 -N concentrations reflect an excess of nitrogen not used for microbial synthesis (Kolver et al., 1998;Russell et al., 1983), which probably occurred due to the high CP concentration and the low concentrations of NFC that are common in intensively managed tropical pastures (Danés et al., 2013). ...
The aim of this study was to evaluate the chemical composition, digestibility, gas production kinetics and in vitro methane (CH4) production of Urochloa brizantha cv. Marandu under two stocking methods over three consecutive stocking cycles. The stocking methods were (1) a fixed‐time stocking cycle of 33 days (33‐SC) with a 30‐day rest period and a 3‐day grazing period, and (2) a variable stocking cycle, with the end of the rest period when the canopy intercepted 95% of the light and a 3‐day grazing period (95‐LI). The average rest period was 24.5‐day (standard deviation of 5.2‐day) for 95‐LI. The in vitro dry matter digestibility (IVDMD) was higher (p < .01) for 95‐LI (646 g/kg) relative to 33‐SC (628 g/kg). Crude protein concentration was higher (p < .01) for 95‐LI (154 g/kg) relative to 33‐SC (136 g/kg). The ADF (303 g/kg DM) and aNDF (623 g/kg) were higher (p < .01) for 33‐SC compared to 95‐LI (287 and 605 g/kg respectively). The gas production potential from non‐fibrous carbohydrates was 9.4% higher for 33‐SC. The in vitro CH4 production per unit of degraded dry matter (DDM) was higher (p < .01) for 33‐SC (19.9 CH4 ml/g), compared to 95‐LI (17.9 CH4 ml/g). The 33‐SC management resulted in rest periods that were too long for the time needed for optimal regrowth. The variable SC based on the 95‐LI was more favourable, because it resulted in maximum yield of dry matter with improved forage nutritive value, while decreasing CH4 yield.
... The literature reports that today it is possible to obtain from 12 to 14 kg/cow/d of milk on elephant grass pastures fertilized with 200 kg/ha/yr of nitrogen during the rainy season when managed under rotational stocking, with a 30-day defoliation interval (DANES et al., 2013). However, due to the reasonable cost of the pasture dry matter, this milk yield level should be maximized by the use of developed techniques for pasture management such as light interception and post-grazing residual heights, as shown in the studies (BRUNETTI et al., 2016;CARVALHO et al., 2017;LEE;DONAGHY;ROCHE, 2008;). ...
The objective of this study was to evaluate nutrient intake and digestibility, yield and components of milk from Holstein × Zebu cows on Tanzania grass pastures using a fixed-rest period or 95% light interception. The treatments consisted of evaluations of two Tanzania-grass pasture-management strategies: LI95 - when the pasture reached 95% light interception (LI), with 3 paddock-occupation days; and FR - the pasture was managed with a 30-days defoliation interval (DI) and 3 paddock-occupation days. Ten recently calved cows per treatment in year 1 and eight cows per treatment in year 2 were used, i.e. five cows per replicate in year 2 and four cows per replicate in year 2. Intake and digestibility of pasture nutrients, milk yield and milk composition were evaluated. The management strategies imposed on the Tanzania-grass pasture did not affect nutrient intake or digestibility. Milk yield and milk components were not affected by the management strategies, but milk yield per area unit was affected by the use of 95% light interception. The management strategy applying 95% light interception implies greater efficiency in the use of area, which translates to a higher milk yield per unit area, and thus it can be recommended to increase milk yield per area.
... Plasma samples were then stored frozen at -20 C for further analysis of glucose and urea nitrogen (PUN), using quantitative colorimetric kits (Numbers G7521 and B7551 respectively; Pointe Scientific Inc., Canton, MI, USA). On the 19th day, ruminal-fluid samples (~100 mL) were collected at 0, 2, 4, 6 and 8 h after supplement feeding, by using a sampling probe as described by Danes et al. (2013). Ruminal pH was measured immediately, and samples were frozen at -20 C for further analyses. ...
Context. Cattle grazing tropical forages usually perform below genetic potential due to limited nutrient intake. Aims. Four experiments were conducted to evaluate supplementation strategies on performance and metabolism of cattle grazing intensively managed marandu palisade grass (Urochloa brizantha). Methods. Experiment 1 evaluated the average daily gain (ADG) of 72 young bulls (222 AE 25 kg bodyweight, BW) grazing palisade grass and supplemented (22% crude protein, CP) at 0.0%, 0.3%, 0.6% and 0.9% BW, and their ADG during the feedlot finishing phase. Experiment 2 evaluated the ADG of 80 bulls (240 AE 18 kg BW) grazing palisade grass and supplemented with energy (11.3% CP) or three protein sources (%20.5% CP) at 0.6% BW. Experiment 3 investigated intake, rumen parameters and digestibility of nutrients in fistulated steers (410 AE 8.6 kg BW) fed an energy supplement, that is, ground corn, at 0.0%, 0.3%, 0.6% and 0.9% BW, with a parallel in vitro study of fermentation kinetics (Experiment 4). Key results. Increased levels of supplementation resulted in linear increases (P < 0.05) in ADG, stocking rate (SR) and in BW gain per area. There were no differences (P > 0.05) in ADG, SR and BW gain per area among supplemental sources of protein or the energy supplement. Increasing energy levels caused a linear decrease (P < 0.05) in forage intake and grazing time and a linear increase (P < 0.05) in total dry matter and digestible-nutrient intakes, but did not affect (P > 0.05) fibre degradability. Corn supplementation also caused a linear decrease (P < 0.05) in acetate : propionate ratio, in ruminal ammonia-N and in N excretion, and a linear increase (P < 0.05) in rumen propionate concentration, in microbial synthesis and in N retention. The supplementation increased BW at the start of the feedlot phase, resulting in similar hot carcass weights with fewer days on feed and no effects on meat quality. Conclusions. Overall, despite the source utilised, supplementation increased ADG, SR and BW gain per area, with fewer days being required on the finishing period. Implications. Having adequate supplementation strategies in place will help producers increase the efficiency of their systems.
... El NUL es considerado un indicador metabólico de la relación energía-proteína en la dieta y de la eciencia del uso de la proteína en rumen (Danes, Chagas, Pedroso, & Santos, 2013;Pardo, Carulla, & Hess, 2008). Los resultados de NUL en el presente estudio estuvieron cercanos al límite superior en el rango optimo (10 a 19 mg/dL NUL), citado por Hess et al. (1999), con excepción del OPDC en el experimento I. Ávila y Lascano (2001) indican que un valor 10 mg/dL puede utilizarse como un punto de referencia para denir el NUL en leche, y que este valor depende del grado de suplementación proteica y del grupo genético de la vaca, con respuestas que van desde incremento en el NUL y en la producción de leche como resultado al aumento del nivel de suplementación proteica en la dieta, principalmente para vacas mestizas, hasta incrementos en NUL sin respuesta en la producción de leche en vacas con fenotipo cebuino. ...
El objetivo del presente trabajo fue evaluar el efecto de subproductos de la palma africana (Elaeis guineensis Jacq.) en la producción y la calidad de la leche bajo condiciones de pequeño productor doble propósito en el sur del departamento del Atlántico, Colombia. Para ello, se estableció un diseño de sobrecambio, balanceado para efectos residuales en seis fincas en Repelón (experimento i), y dos fincas en Manatí y cuatro en Campo de la Cruz (experimento ii). Se suplementó durante un periodo de acostumbramiento y evaluación, torta de palmiste (pkc) y decantado de lodos (opdc) como dietas experimentales, y se comparó con sal mineralizada (SalM). Las dietas afectaron (p < 0,05) la producción de leche. El opdc registró la mayor producción de leche (3,20 y 4,01 L/vaca/día en experimentos i y ii, respectivamente), sin diferencia (p > 0,05) con el pkc, aunque superior (p < 0,05) al tratamiento con SalM (2,91 y 3,38 L/vaca/día en experimentos i y ii, respectivamente). La calidad composicional de la leche fue afectada por las dietas evaluadas (p < 0,05). Las dietas afectaron la concentración de nitrógeno ureico en leche (p < 0,05), indicando posibles alteraciones en la relación de proteína degradable en rumen y carbohidratos fermentables. El opdc y el pkc se presentan como suplementos promisorios para mejorar la producción de leche bajo condiciones de pequeño productor en el sur del Atlántico.
... As the global population of goats is approximately 654 million the goat industry should take responsibility for N excretions [5]. According to previous studies, reducing dietary protein level is an effective way to reduce N excretion [6,7]. ...
The effects of decreasing dietary crude protein (CP) level on growth performance, nutrient digestion, serum metabolites, and nitrogen utilization in growing goat kids were investigated in the current study. Thirty-six male Anhui white goat kids were randomly assigned to one of three CP content diets: 14.8% (control), 13.4%, and 12.0% of dry matter, respectively. Diets were isoenergetic. The experiment lasted for 14 weeks, with the first two weeks being for adaptation. Results showed that the low-CP diet decreased average daily gain, feed efficiency, digestibility of dry matter, organic matter, crude protein, and fiber. No significant changes were observed in dry-matter intake. With a decrease in dietary CP level, fecal nitrogen excretion (% of nitrogen intake) increased linearly, whereas CP intake, blood urea nitrogen, urinary nitrogen excretion (% of nitrogen intake), and total nitrogen excretion (% of nitrogen intake) decreased. Serum glucose concentration decreased, while concentrations of low-density lipoproteins and non-esterified fatty acids increased with the low-CP diet. In conclusion, decreasing the dietary CP level decreased goats’ nitrogen excretion, but with restrictive effects on growth performance. A diet containing 13.4% CP is optimal for reducing nitrogen excretion without any adverse effect on growth performance of Anhui white goat kids. This concentration is 1.4% points lower than the NRC recommendations and thus is also environmentally beneficial on the input side because it decreases the use of feed (soy) protein.
... The review by Chilliard, et al. [7] summarized the effects of forage type on milk fat and composition, and highlighted the need to evaluate the impact of feeding systems on other aspects of milk fat quality, such as flavor and oxidative stability. Milk produced from many supplemented and altered diets have been investigated, including supplementation with flaxseed [8], lipid complex [9], crude protein [10], iodine [11] marine algae [12], oregano and caraway essential oils [13], hull-less barley [14] and sunflower/fish oil [15]. These studies focused mainly on animal production performance, milk composition, milk yield, milk fatty acid composition, and to a lesser extent on the flavor and sensory characteristics of milk. ...
The main aim of this study was to evaluate the volatile profile, sensory perception, and phytochemical content of bovine milk produced from cows fed on three distinct feeding systems, namely grass (GRS), grass/clover (CLV), and total mixed ration (TMR). Previous studies have identified that feed type can influence the sensory perception of milk directly via the transfer of volatile aromatic compounds, or indirectly by the transfer of non-volatile substrates that act as precursors for volatile compounds. In the present study, significant differences were observed in the phytochemical profile of the different feed and milk samples. The isoflavone formonoetin was significantly higher in CLV feed samples, but higher in raw GRS milk, while other smaller isoflavones, such as daidzein, genistein, and apigenin were highly correlated to raw CLV milk. This suggests that changes in isoflavone content and concentration in milk relate to diet, but also to metabolism in the rumen. This study also found unique potential volatile biomarkers in milk (dimethyl sulfone) related to feeding systems, or significant differences in the concentration of others (toluene, p-cresol, ethyl and methyl esters) based on feeding systems. TMR milk scored significantly higher for hay-like flavor and white color, while GRS and CLV milk scored significantly higher for a creamy color. Milk samples were easily distinguishable by their volatile profile based on feeding system, storage time, and pasteurization.
... Total apparent digestibility was calculated using the equation: Nutrient digestibility, g/kg DM = ([Nutrient intake, kg − Faecal nutrient output, kg]/Nutrient intake, kg). On day 16, rumen fluid samples (50 ml) were obtained from each steer via ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22 and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth and the pH was immediately recorded using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda, São Paulo, SP, Brazil). ...
The current study evaluated growth performance and digestion responses of finishing bulls fed diets containing 825 g/kg flint maize [dry matter (DM) basis] ground to medium (1.66 mm; MG) or coarse particle sizes (2.12 mm; CG), with added monensin (26 mg/kg; DM basis; MON) or a blend of essential oils (BEO) + exogenous α -amylase (AM; 90 mg/kg + 560 mg/kg commercial product, respectively, DM basis). In Expt 1, 256 Nellore bulls were blocked by initial body weight (BW) (360 ± 11.7 kg) and assigned to 48 pens in a 2 × 2 factorial arrangement of treatments. Effect of a maize particle size × feed additive interaction was not detected for final BW, DM intake (DMI), average daily gain (ADG) and feed efficiency. The DMI was greater for bulls fed BEO + AM v. MON. Final BW and ADG tended to be greater for bulls fed CG than MG maize. An interaction was detected for hot carcass weight which was 11 kg heavier for bulls fed BEO + AM v. MON in diets containing CG, but not MG particle size. In Expt 2, four ruminally cannulated Nellore steers were offered the same treatments as Expt 1, in a 4 × 4 Latin Square design. Intake of most nutrients was greater for steers fed CG than steers fed MG maize. In summary, feeding bulls CG maize increased growth performance and carcass characteristics compared with MG. The combination of BEO + AM resulted in heavier carcass weights compared with MON supplementation when included in diets containing CG maize.
... ndo o efeito da substituição total do farelo de soja por milho e ureia sobre perfil metabólico proteico de vacas mestiças em lactação sob pastejo de capim Mombaça. Esses autores observaram que a substituição do farelo de soja por milho e ureia influenciou de forma linear decrescente as concentrações de NUP, cujos valores médios foram de 17,2 mg/dL.Danes et al. (2013) avaliaram níveis crescentes de PB (8,7%, 13,4% e 18,1%) no concentrado em vacas leiteiras mestiças em pastagens tropicas e encontraram valores de NUP entre 14,8 e 17,7 mg/dL, que são valores considerados dentro da faixa considerada normal, onde promove um melhor aproveitamento de nutrientes advindos de fonte microbiana. De maneira geral ...
The objective of this review was to describe the main factors that influence the production of dairy cows submitted to grazing and the importance of the evaluation of milk and plasma urea nitrogen for animal performance. Pastures are of fundamental importance in Brazilian cattle raising, guaranteeing low production costs since it is the most economical and practical way to produce and offer food for the herd. However, despite the great diversity of grasses with high-quality forage potential, several regions in Brazil present low productivity. In recent years, due to advances in genetic improvement in dairy cows the consumption of protein sources has become a limiting factor for milk production, especially when reared on grazing. The concentration of milk urea nitrogen (MUN) and plasma urea nitrogen (PUN) can be used to monitor crude protein intake, which should be as close as possible to the required requirements of the nutrient by the animal. When MUN values are high (>18 mg/dL) may indicate excess crude protein (CP) in the diet, both the rumen degradable protein fraction (RDP) and the rumen undegradable protein (RUP), ruminal fermentation rate of the non-fibrous carbohydrates fraction (NFC), or protein:energy ratio increased. Low values of MUN (<11 mg/dL) may indicate a deficiency of CP in the diet, limited amounts of RDP and RUP, or a high rate of fermentation of NFC in the rumen. We emphasize the need to seek nutritional strategies by adjusting the MUN and PUN contents according to what is recommended in the literature, that can maximize production, supplying the nutritional limitations imposed on the animals, especially those kept in tropical pastures, reduce production costs and even reduce the environmental impact caused by excess nitrogen excreted.
... On day 16, approximately 50 mL of rumen fluid samples were obtained from each steer via the ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22, and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth with ruminal pH being measured immediately using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda., São Paulo, SP, Brazil). ...
The aim was to evaluate the effects of feeding β-carotene and vitamins on reproduction performance of grazing primiparous beef cows. The experiment was conducted in a commercial farm located in Sidrolandia, MS, Brazil during the spring/summer reproduction season. A total of 204 suckled Nellore primiparous cows (Bos indicus) were used. The animals were maintained in 2 paddocks of Brachiaria brizantha with ad libitum access to water. The cows were homogeneously assigned into groups according the calving date (29.1 ± 5.0 days postpartum), BCS (3.77 ± 0.4) and β-carotene blood concentration (3.96 ± 0.7) to receive treatments for 90 days (30 before and 60 after IA): Control (mineral supplement, n=102) and treated (mineral supplement with 500 mg β-carotene, 70.000 IU vitamin A, 10.000 IU vitamin D3, 500 mg vitamin E and 20 mg biotin/cow/day; n=102). The supplements were daily offered in collective feeders. The β-carotene, vitamins and minerals were provided by DSM Produtos Nutricionais Brasil S.A. Cows were rotated through the paddocks every 15 days to avoid effects of pasture availability and quality. Cows were synchronized at 49 days postpartum using an estradiol/progesterone based FTAI protocol: D0 – insertion of progesterone device and treatment of 2.0 mg estradiol benzoate IM; D9 – treatment of 0.530 PFG2α analogue, 300 IU of eCG, 1.0 mg estradiol cypionate and progesterone device withdrawal; D11 - FTAI. Data were analyzed using the PROC MIXED procedure of SAS. The conception rate at FTAI tended to be greater (P=0.07) in primiparous cows supplemented with β-carotene and vitamins (68.6%; 70/102) compared to control group (58.8%; 60/102). In conclusion, feeding grazing primiparous Nellore cows with a combination of β-carotene and vitamin A, D, E and biotin can increase conception rate at FTAI by 16.6%.
... On day 16, approximately 50 mL of rumen fluid samples were obtained from each steer via the ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22, and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth with ruminal pH being measured immediately using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda., São Paulo, SP, Brazil). ...
Two experiments were conducted to evaluate the performance responses of finishing feedlot cattle to dietary addition of essential oils and exogenous enzymes. The treatments in each experiment consisted of (dry matter basis): MON - sodium monensin (26 mg/kg); BEO- a blend of essential oils (90 mg/kg); BEO+MON- a blend of essential oils plus monensin (90 mg/kg + 26 mg/kg, respectively); BEO+AM- a blend of essential oils plus exogenous α-amylase (90 mg/kg + 560 mg/kg, respectively); and BEO+AM+PRO - a blend of essential oils plus exogenous α-amylase and exogenous protease (90 mg/kg + 560 mg/kg + 840, mg/kg respectively). Exp. 1 consisted of a 93-d finishing period using 300 Nellore bulls in a randomized complete block design. Animals fed BEO had higher dry matter intake (P < 0.001) but similar feed efficiency to animals fed MON (P ≥ 0.98). Compared with MON, the combination of BEO+AM resulted in 810 g greater dry matter intake (P = 0.001), 190 g greater average daily gain (P = 0.04), 18 kg heavier final body weight (P = 0.04) and 12 kg heavier hot carcass weight (P = 0.02), although feed efficiency was not significantly different between BEO+AM and MON (P = 0.89). Combining BEO+MON tended to decrease hot carcass weight compared with BEO alone (P = 0.08) but not compared with MON (P = 0.98). Treatments did not impact observed dietary net energy values (P ≥ 0.74) or the observed:expected net energy ratio (P ≥ 0.11). In Exp. 2, five ruminally cannulated Nellore steers were used to evaluate intake, apparent total tract digestibility of nutrients, and ruminal parameters in a 5 × 5 Latin Square design. Feeding BEO increased the total tract digestibility of CP compared to MON (P = 0.03). Compared to MON, feeding the combination of BEO+MON increased the intake of CP (P = 0.04) and NDF (P = 0.05), with no effects on total tract digestibility of nutrients (P ≥ 0.56), except for a tendency (P = 0.09) to increase CP digestibility. Intakes of all nutrients measured, except for EE (P = 0.16) were greater in animals fed BEO+AM when compared with MON (P ≤ 0.03), with no differences on total tract nutrient digestibilities (P ≥ 0.11) between these two treatments. In summary, diets containing the BEO used herein enhanced dry matter intake of growing-finishing feedlot cattle compared with a basal diet containing MON without impair feed efficiency. A synergism between BEO and AM was detected, further increasing cattle performance and carcass production compared to MON.
... Cows fed higher CP concentrations excreted greater amounts of urea nitrogen in milk (linear effect, p<0.01), indicating inefficiency in the use of dietary nitrogen for productive purposes with increased CP. Similar results were reported by Danes et al. (2013) and Arriola Apelo et al. (2014). Feeding excess nitrogen requires the use of additional energy to metabolize excess protein as observed by Reed et al. (2017), who found increases in heat production and decreases in energy retained in tissue and in milk gross energy after Holstein cows were fed diets with excess nitrogen. ...
The objective of this work was to evaluate the effect of reducing crude protein (CP) contents in diets with a constant metabolizable protein content on the intake, performance, nitrogen balance, and nutrient digestibility of lactating Holstein-Gyr cows. Animals (n = 24, 103±23 days in milk) were allocated to four treatments (n = 6 per group) with different CP contents: 127, 132, 139, and 156 g kg-1 dry matter (DM). DM intake was not affected by treatments. CP intake and digestibility increased linearly with higher CP contents. Milk yield (23.7±3 kg per day) and the percentages of milk protein (3.3±0.2%) and fat (3.8±0.5%) were not affected by CP reduction. Milk and blood urea nitrogen increased linearly with the increase of CP in the diet, similarly to urinary nitrogen excretion. Nitrogen use efficiency was 29.8 and 22.4% when CP was 127 and 156 g kg-1 DM, respectively. Reducing CP in diets fed to mid-lactating Holstein-Gyr cows increases nitrogen use efficiency and maintains the productive performance of the cows.
... Concentrate meals were fed individually twice daily (4:30 am and 2:30 pm) before milking (5 am and 3 pm) at a rate of 1 kg of concentrate/3 kg of milk (considering the average of each block). The rate was established based on milk yield at the beginning of each period (Danes et al., 2013). The concentrate meal was composed of citrus pulp (35%), corn gluten feed (30%), fine ground corn (20%), soybean meal (10%) and mineral (5%), with chemical composition as followed: 88.4% DM, 10.3% ash, 14.0% CP, 22.2% NDF, 9.3% ADF, 3.3% ether extract and 49.8% non-fibrous carbohydrate. ...
... On day 16, approximately 50 mL of rumen fluid samples were obtained from each steer via the ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22, and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth with ruminal pH being measured immediately using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda., São Paulo, SP, Brazil). ...
... On day 16, approximately 50 mL of rumen fluid samples were obtained from each steer via the ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22, and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth with ruminal pH being measured immediately using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda., São Paulo, SP, Brazil). ...
... On day 16, approximately 50 mL of rumen fluid samples were obtained from each steer via the ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22, and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth with ruminal pH being measured immediately using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda., São Paulo, SP, Brazil). ...
... On day 16, approximately 50 mL of rumen fluid samples were obtained from each steer via the ruminal cannula at 0, 2, 4, 6,8,10,12,14,16,18,20,22, and 24 h after feeding as described by Danes et al. (2013). Ruminal fluid samples were squeezed through four layers of cheesecloth with ruminal pH being measured immediately using a portable pH meter (Digimed Model DM22, Digicrom Analítica Ltda., São Paulo, SP, Brazil). ...
... Em trabalho realizado no Sistema de Produção de Leite da Escola Superior de Agricultura "Luiz de Queiroz" (Esalq), em Piracicaba (DANÉS et al., 2013), foram testados três concentrados diferentes para vacas em lactação mantidas em pastagens de capim-elefante de elevada qualidade. A forragem apresentava 18,5% PB, 60,3% NDT, 58,7% FDN e 75,9 % de digestibilidade. ...
... Holstein-based, crossbreds), level of intensification, and animal management, among other factors. The database comprised of 37 scientific papers published in peer-reviewed journals from 1992 to 2014 (Erasmus et al. 1992(Erasmus et al. , 1994(Erasmus et al. , 1999(Erasmus et al. , 2004(Erasmus et al. , 2013Auldist et al. 1999;Kalscheur et al. 1999;Murphy 1999;Abdullah et al. 2000;Kokkonen et al. 2000;Alvarez et al. 2001;O'Mara et al. 2000;Bargo et al. 2001;McCormick et al. 2001aMcCormick et al. , 2001bAssis et al. 2004;Heard et al. 2004;Colmenero and Broderick 2006;Oguz et al. 2006;Heard et al. 2007;Fatahnia et al. 2008;Meeske et al. 2009;Piamphon et al. 2009;Sun et al. 2009;Grainger et al. 2010;Moharrery 2010;Valizadeh et al. 2010;Walker et al. 2010;Irvine et al. 2011;Petit and Gagnon 2011;Yalçın et al. 2011;Lunsin et al. 2012;Mosavi et al. 2012;Vafa et al. 2012;Greenwood et al. 2013;Danes et al. 2013;Dey and De 2014). The database contained 173 observations (19 for Africa, 45 for Asia, 16 for Europe, 12 for Latin America, 44 for North America, and 37 for Oceania) with the minimum information needed for simulation, such as animal and feedstuff characteristics, DM intake (DMI), and milk composition and production. ...
The contemporary concern about anthropogenic release of greenhouse gas (GHG) into the environment and the contribution of livestock to this phenomenon have sparked animal scientists' interest in predicting methane (CH4) emissions by ruminants. We contend that improving the adequacy of mathematical nutrition model estimates of production of meat and milk is a sine qua non condition to reliably determine ruminants' worldwide contribution to GHG. Focusing on milk production, we address six basic nutrition models or feeding standards (mostly empirical systems) and five complex nutrition models (mostly mechanistic systems), describe their key characteristics, and highlight their similarities and differences. We also present derivative systems. We compiled a database of milk production information from 37 published studies from six regions of the world, totalling 173 data points: 19 for Africa, 45 for Asia, 16 for Europe, 12 for Latin America, 44 for North America and 37 for Oceania. Four models were used to predict milk production in lactating dairy cows, and the adequacy of their predictions was measured against the observed milk production from our database. Even though these mathematical nutrition models shared similar assumptions and calculations, they have different conceptual and structural foundations inherent to their intended purposes. A direct comparison among these models was further complicated by the different models requiring unique inputs that are very often not available, and the low reliability of the inputs prevents an unbiased assessment of the model predictions. Very few studies have collected the necessary information to run more mechanistic systems, and users have to rely on standard information to populate many model inputs. Study effect was a critical source of variation that limited our ability to conclusively evaluate the models' applicability under different scenarios of production around the world. Only after study variation was removed from the database did the adequacy of the model predictions of milk production improved, but deficiencies still existed. On the basis of these analyses, we conclude that not all models were suitable for predicting milk production and that simpler systems might be more resilient to variations in studies and production conditions around the world. Improving the predictability of milk production by mathematical nutrition models is a prerequisite to further development of systems that can effectively and correctly estimate the contribution of ruminants to GHG emissions and their true share of the global warming event.
To evaluate the influence of supplementation strategies on the average daily gain (ADG) of cattle in a rotational grazing system of Guinea grass (Panicum maximum cv. Coloniao) pastures during the rainy season. It was further evaluated the residual effects in the feedlot finishing phase. Seventy-five 8 month-old crossbred bull calves averaging 200.1 ± 2.5 kg of body weight (BW) were stratified and grouped in three into 25 blocks according to BW, and then randomly assigned to one of three supplementation treatments: control (no supplement), energy supplement [65 g crude protein (CP)/kg dry matter (DM)] or protein supplement (200 g CP/kg DM) both fed as 6 g/kg BW. All animals composed a single herd and were separated daily according to treatment groups for supplementation. After the grazing phase, all animals were moved to a feedlot and received the same diet up until slaughter. Guinea grass was subjected to rotational stocking with pre- and post-grazing heights of 76 and 43 cm, respectively. Energy and protein supplements provided similar ADG (P > 0.05; 0.94 kg/day) which was greater than for non-supplemented animals during the grazing phase (P ≤ 0.05; 0.74 kg/day), but there was no difference in the subsequent feedlot phase (P > 0.05; 1.45 kg/day). The protein supplement had no incremental effects over the energy supplement on ADG and carcass traits of growing crossbreed bulls during the grazing phase, indicating that either source could be used, and that an energy supplement would lead to more efficient nutrient use coming from the grass
The objective of this study was to investigate the effects of energy supplementation and pre-grazing sward height on grazing behavior, nutrient intake, digestion and metabolism of cattle in tropical pastures managed as rotational grazing system. Eight rumen-cannulated Nellore steers (24 months age; 300 ± 6.0 kg body weight) were used in a replicated 4 x 4 Latin square design. Treatments consisted of two levels of energy supplementation [0 (none) or 0.3% of body weight (BW) of ground corn on an as-fed basis] and two pre-grazing sward heights [25 cm (defined by 95% light interception) or 35 cm (defined by ≥ 97.5% light interception] constituting 4 treatments. Steers grazed Marandu Palisadegrass [Brachiaria brizantha Stapf. cv. Marandu] and post-grazing sward height was 15-cm for all treatments. Forage dry matter intake (DMI) was increased (P = 0.01) when sward height was 25 cm (1.86 vs 1.32% BW) and decreased (P = 0.04) when 0.3% BW supplement was fed (1.79 vs 1.38% BW). Total and digestible DMI were not affected by energy supplementation (P = 0.57) but were increased when sward height was 25-cm (P = 0.01). Steers grazing the 25-cm sward height treatment spent less time grazing and more time resting, took fewer steps between feeding stations, and had a greater bite rate compared with 35-cm height treatment (P < 0.05). Energy supplementation reduced grazing time (P = 0.02) but did not affect any other grazing behavior parameter (P = 0.11). Energy supplementation increased (P < 0.01) diet dry matter digestibility but had no effect on crude protein and neutral detergent fiber digestibilities (P = 0.13). Compared to 35-cm pre-grazing sward height, steers at 25-cm presented lower rumen pH (6.39 vs 6.52), greater rumen ammonia nitrogen (11.22 vs 9.77 mg/dL) and N retention (49.7 vs 20.8%, P < 0.05). The pre-grazing sward height of 25-cm improved harvesting efficiency and energy intake by cattle, while feeding 0.3% of BW energy supplement did not increase energy intake of cattle on tropical pasture under rotational grazing.
The objective for this study was to evaluate the supplementation with different non-fibrous carbohydrate (NFC) sources for grazing dairy cows in diets with high or low concentrations of rumen undegradable protein (RUP). Twelve multiparous cows averaging 30kg/d of milk production and 45±23 days in milk in a 4x4 Latin square design with 2 × 2 factorial arrangement were used. The difference in NFC content of the diets was achieved using ground corn (GC) or dried citrus pulp (DCP). Dietary RUP was altered by the partial replacement of soybean meal (LRUP) by roasted whole soybean and corn gluten meal (HRUP). Greater dry matter intake (DMI) was observed in DCP treatments compared to GC treatments (19.2 and 17.7kg/day of DM, respectively). Milk fat concentration was lower for LRUP treatments (3.4%) when compared to HRUP (3.6%). The milk protein concentration was greater for GC treatments (2.9%) in relation to DCP treatments (2.8%). Lower milk ureic nitrogen was observed when DCP diets were fed compared to those with GC (17.8 and 21.2mg/dL, respectively). The use of DCP as CNF source increased dry matter intake as well as milk fat concentration, although no differences in milk production were observed for RUP level.
Current experiment evaluated the effect of replacement of full corn meal by dehydrated ground cassava roots at levels 0%, 25%, 50%, 75% and 100% in experimental supplements for lactating cows grazing on irrigated and fertilized tropical pastures. Ten Holstein cows were divided into two 5 x 5 Latin squares, with average initial 150 days of lactation, milk production 22±3.30 kg day-1 at the beginning of experiment and initial body weight of 603±65 kg. Cows were maintained on pasture consisting of elephant grass (Pennisetum purpureum, Schum) cultivar Pioneiro, intercropped with Tifton 85 (Cynodon nlemfuensis), fertilized with 600 kg nitrogen per hectare year-1. There was no significant difference (p > 0.05) between the substitution levels of corn meal by ground and dehydrated cassava root in the concentrate on the synthesis of microbial protein with an estimated average of 1,288.49 g day-1 and efficiency in the synthesis of microbial protein per kilogram of TDN with estimated average of 91.30 g kg-1 TDN. Nitrogen equilibrium showed an estimated average of 218.79 g day-1 of retained nitrogen. The microbial protein synthesis and nitrogen balance were not affected by treatments.
Current experiment evaluated the effect of replacement of full corn meal by dehydrated ground cassava roots at levels 0%, 25%, 50%, 75% and 100% in experimental supplements for lactating cows grazing on irrigated and fertilized tropical pastures. Ten Holstein cows were divided into two 5 x 5 Latin squares, with average initial 150 days of lactation, milk production 22±3.30 kg day-1 at the beginning of experiment and initial body weight of 603±65 kg. Cows were maintained on pasture consisting of elephant grass (Pennisetum purpureum, Schum) cultivar Pioneiro, intercropped with Tifton 85 (Cynodon nlemfuensis), fertilized with 600 kg nitrogen per hectare year-1. There was no significant difference (p > 0.05) between the substitution levels of corn meal by ground and dehydrated cassava root in the concentrate on the synthesis of microbial protein with an estimated average of 1,288.49 g day-1 and efficiency in the synthesis of microbial protein per kilogram of TDN with estimated average of 91.30 g kg-1 TDN. Nitrogen equilibrium showed an estimated average of 218.79 g day-1 of retained nitrogen. The microbial protein synthesis and nitrogen balance were not affected by treatments.
In our experiment, we studied the effects of protein concentrate addition on the qualitative and quantitative composition of milk in organically farmed dairy cows. A total number of 40 Holstein cows were divided into two groups. Live weight of dairy cows was around 625±25 kg. Average production efficiency of animals was 7600±50 kg milk for the lactation period. Animals of both groups received identical basal feed ration. The first experimental group of cows (n=20) received in the feed ration a protein concentrate from organic production (soybean cake 60%, sunflower cake 20%, linseed cake 20%) at 1 kg per head and day. The second group served as a control (n=20) without the addition of protein concentrate. The experiment lasted 30 days. The goal of the experiment was to investigate whether the addition of protein concentrate can affect individual milk components. The measured values show that the experimental group of dairy cows with the addition of protein concentrate exhibited increases in fat content by 7.4% (P≤0.05), in urea content by 83.1% (P≤0.001) and in citric acid content by 18.6% (P≤0.01), and decreases in free fatty acids by 54.9% (P≤0.001), in ECM by 5.5% (P≤0.05) and in FCM by 6.1% (P≤0.05). The control group of cows exhibited the citric acid content in milk increased by 20.0% (P≤0.05). The results indicate that the protein concentrate composed of soybean, sunflower and linseed cakes can affect the composition of milk from organically farmed dairy cows
Abstract Text:
Most of the grassland areas in Brazil are covered with tropical grasses. The majority of the milk (Stock et al, 2011) and beef (Millen et al., 2009) are produced on pasture based systems. In intensive grazing systems during the hot rainy season, stocking rates of 6 to 10 AU//ha (1 AU = 450 kg BW) can be achieved (Santos et al., 2014). Despite the high stock capacity, the average daily gain (ADG) and milk production are lower than the animals genetic potential and this is attributed to the limited energy intake. Some of the major factors imposing limitations to energy intake by the animals in tropical grazing systems are: a) low efficiency of the grazing process because of sward structure and b) rumen fill. During the last 2 decades, considerable amount of information has been published related to new management practices of tropical pastures. The adoption of the start grazing point based on the 95% light interception criterion, has successfully resulted in a more favorable sward structure which allows the animal to harvest a greater daily amount of forage in a shorter grazing period. However, even when all the available technology on tropical pasture management is applied, forage intake is still limited because of rumen fill. The quality of the tropical forage NDF (IVNDFD) is greater than for alfalfa. However the NDF content (51 to 65%) and its low cell fragility cause rumen fill and they limit energy intake. Studies related on cell fragility of tropical grasses are limited and this topic deserves more attention. Supplementing high energy concentrates for grazing cattle is at the same time, an efficient strategy to increase energy intake and to decrease the energy expended with the grazing activity. The substitution effect observed when concentrate is fed to grazing cattle is related not only to the amount of concentrate fed, but it is also related to the pasture management practices.
Keywords: grazing, nutrient intake, efficiency
Tropical grasses are the primary forages grown for pasture in most regions of Brazil. They are generally described as low quality forages, but with high potential for herbage mass accumulation. However, recent adoption of intensive management grazing practices has improved forage quality of tropical grasses. This study was conducted to characterize the nutrient profile and fiber digestibility of the main tropical grasses produced under intensive rotational grazing management in Brazil and further to develop NIRS (near-infrared reflectance spectroscopy) calibrations to equation to predict nutrient content and fiber digestibility of these tropical grasses. One-hundred six samples of Palisade grass (Brachiaria brizantha); Mulato grass (Brachiaria hibrida), Bermuda grass (Cynodon dactylon); African Bermuda grass (Cynodon nlemfuensis), Guinea grass (Panicum maximum) and Elephant grass (Penisetum purpureum) were collected from intensively managed paddocks after less than 30-d of re-growth. In Experiment A, in vitro NDF digestibility (IVNDFD) assay was performed according to the Goeser and Combs method. Each sample was analyzed three times and digested, in duplicates, for 24-, 30- and 48-h. Tropical grasses had high CP and relatively low NDF content, ranging from 14 to 21 % and 60 to 63 % of DM, averaged by grass species. Means of 24-, 30-, and 48-h IVNDFD were 36 ± 13, 45 ± 13 and 61 ± 13 % of NDF, respectively across forages species. Across incubation times, IVNDFD was higher for Bermuda and African Bermuda grass (53 and 50 % of NDF, respectively) and lower for Elephant and Palisade grass (44 % of NDF for both species). Forage specie had a significant effect on IVNDFD, even though these samples had similar NDF content. In Experiment B, 99 samples from Experiment A were scanned using a NIRS instrument and corresponding nutrient composition and fiber digestibility measurements were used for development of a NIRS calibration equation. The NIRS calibration equation R2 values were 0.79, 0.77 and 0.73 for 24-, 30-, and 48-h IVNDFD. Results indicate that there is potential to determine fiber digestibility by NIRS; however, further studies should be directed to specific forage species, and a larger and more diverse sample set, capable of representing distinct conditions, would be required to predict fiber digestibility of tropical grasses more precisely. Correlation coefficients between fiber digestibility and chemical constituents indicated that IVNDFD of tropical grasses is not related to neither NDF, ADF, or grass lignin content. Our findings indicate that tropical forages subjected to intensive grazing management practices can be relatively high in crude protein content and fiber digestibility, and low in fiber content. Moreover, results suggest the relationship between lignin and digestibility is probably different between tropical and temperate grasses, and also differ within species of tropical grasses.
Grazing management is a key element determining herbage production and grazing efficiency. This study measured herbage accumulation and grazing efficiency in Mombaça grass pastures (Panicum maximum cv. Mombaça) subjected to intermittent defoliation managements. Treatments were combinations of 2 rest periods (grazing at either 95 or 100% canopy light interception - LI) and 2 grazing intensities (30 and 50 cm post-grazing height), and were allocated to 2000 m 2 plots according to a complete randomised block design, in a 2 x 2 factorial arrangement, with 4 replications. Response variables measured from January 2001 to February 2002 were: sward height, herbage mass and morphological composition pre-and post-grazing, and losses due to grazing. Effective values for the 95 and 100% LI targets were 95.5 and 98.5%, respectively, and corresponded with 90 and 115 cm sward height, throughout the experiment, indicating that this could be a satisfactory parameter for monitoring grazing on farms. The apparently small difference in pre-grazing targets was large enough to cause changes in dry matter accumulation and composition of the herbage mass. The 95/30 treatment resulted in lowest pre-grazing herbage mass, shortest rest period (22-24 days in spring-summer and 95 days in autumn-winter) but highest total herbage accumulation (26 890 ± s.e.m. 2506 kg/ha DM). It also resulted in high proportion of live leaf (71%) and low proportion of live stem (15%) pre-grazing. Averaged over the 30 and 50 cm treatments, there was no difference in total herbage accumulation (22 780 ± 1772 kg/ha DM) and total herbage disappearance (20 160 ± 1170 kg/ha DM) for the LI treatments. However, grazing losses were higher for the 100% (5860 ± 550 kg/ha DM) than 95% LI treatments (4060 ± 550 kg/ha DM). Consequently, the amount of herbage effectively harvested and grazing efficiency were higher for the 95% than 100% LI treatments. The 95/30 treatment resulted in highest total herbage accumulation (26 890 ± 2506 kg/ha DM) and grazing efficiency (87%).
Urea has been fed in ruminant rations for more than 100 yr. Its use in dairy cattle rations has fluctuated with protein and urea prices, with various values used in different formulation systems, and with mixed to negative experiences in experiments and field situations. In many studies, rations were not isocaloric when urea was added, and intake reduction occurred because of high dietary levels of urea. Some studies concluded that cows disliked the flavor or odor of urea, or that there was some metabolic component. A series of studies revealed that cows did not dislike the flavor or odor of urea per se, that they could identify different levels of urea in rations, that they developed a conditioned negative aversion to urea when urea was fed at higher levels and for several exposures, and that 135 g/cow daily did not reduce DMI. In older studies, and in even more recent ones, this level of urea intake has been exceeded by 50 and up to 300% with a corresponding DMI decrease, even when fed in TMR. Urea use has also been limited because of in vitro studies showing no benefit to adding urea if ammonia levels are at 5 mg/mL or dietary CP is at 13%. However, several in vivo and in situ studies have shown the optimal rumen ammonia level to be between 17 and 25 mg/mL when DM disappearance and nonammonia-N flow are the determining measurements. Several studies have shown that oils, especially more unsaturated oils, defaunate or reduce protozoa, which can increase microbial protein synthesis efficiency but reduce DMI. In one study, the authors speculated that addition of urea could be beneficial to counteract reduced rumen ammonia and pH. Although there is some belief that addition of urea to higher nitrate-containing diets exacerbates the situation, studies do not support this contention.
The aim of this work was to evaluate the effects of in situ incubation time and particles size on the estimates of indigestible fractions of dry matter (iDM), neutral detergent fiber (iNDF), and acid detergent fiber (iADF) in cattle feeds and feces. Samples of corn grain, wheat bran, corn silage, elephant grass, sugarcane, signal grass hay, corn straw, and feces obtained from cattle fed high and low concentrate diets were used. The samples were ground through 1 mm, 2 mm, and 3 mm screen sieve and put in 4 × 5 cm non-woven textile bags (20 mg DM/cm² of surface). The samples were divided in three groups, being each group incubated in the rumen of a crossbred heifer. The incubation procedure was conducted three times with the change of groups among animals. The following incubation times were used: 0, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, and 312 hours. The contents of iDM, iNDF, and iADF were evaluated sequentially in each bag. The degradation profiles were interpreted by a non-linear logistic model. The particles size did not influence the estimates of iNDF and iADF. However, the particles size altered the rumen degradation dynamic rates of DM for corn silage and corn grain; of NDF for sugarcane, corn silage, and corn straw; and ADF for sugarcane. For those samples, the particle size has been positively associated with the incubation time necessary to estimate the indigestible fraction. Incubation times of 240 hours for DM and NDF, and 264 hours for ADF were suggested for obtaining more accurate estimates of indigestible fractions. The use of 2 mm particle size can increase the precision of estimates.
The objective of this study was to evaluate two grazing intervals (IG) for elephant grass (Pennisetum purpureum Schum cv. Cameroon) pasture: one variable, determined by the entry of animals to the paddocks when 95% of active photosynthetic radiation was intercepted by the sward, and fixed 26-day grazing interval. Eight dairy cows were used, averaging 124 days lactation, 516 kg body weight and 17.5 kg daily milk production at the beginning of the trial. The experimental period was 80 days divided into four sub-periods of 20 days each. Data were analyzed in a cross-over design. The grazing frequencies did not influence milk production and composition, plasma urea nitrogen, body condition score and variations in body weight. However, the stocking rate and milk production per hectare were higher for pasture with interval of grazing determined by 95% of active photosynthetic radiation. Thus grazing frequency defined in variable intervals by sward interception of active photosynthetic radiation result in higher milk production per area unit.
The aim of this research was to evaluate the use of a low level of chromium oxide (Cr2O3) incorporated into the concentrate ration to estimate faecal output (FO) in cattle. Four in vivo digestibility essays were conducted using four steers with live weights of 214±31kg, receiving fresh Italian ryegrass (Lolium multiflorum Lam.). About 200g of concentrate with 5g kg-1 of Cr2O3 was daily rationed during 12 days, where 7 days were used for animal adaptation and 5 days for measurements. The total faecal output was collected and compared with faecal output estimated from grab samples, collected twice a day (8:00 am and 4:00 pm) or at 2-hour intervals, from 8:00 am to 10:00 pm. The average faecal chrome concentration collected at 08:00 am and 04:00 pm (445mg kg-1) was similar with the average of samples collected at a 2-hour interval (447mg kg-1). The marker recovery rate (RR) increased linearly, from approximately 40% to around 80%, with the faecal chrome concentration until approximately 250mg kg-1 OM. When the faecal chrome concentration was higher than 250mg kg-1 OM the RR was relatively constant, with values around 0.76. The faecal output was overestimated up to 35% when the RR was not considered. When the RR was used, faecal output estimative was similar to the total faecal output collected. The faecal output can be accurately estimated in cattle eating ryegrass using a low level of Cr2O3 incorporated into the concentrate ration concomitant with twice-a-day faecal grab samples collection.
To evaluate the effect of feeding concentrate with different crude protein (CP) contents, lactating dairy cows grazing elephant grass were distributed in a 3x3 latin square. Three kg/cow of concentrates (15.2, 18.2, or 21.1% CP) were offered twice a day. Elephant grass dry matter (DM) availability was 1,873kg/ha; with a daily offer of 17.4kg/cow. The elephant grass DM content was 19.6% with 13.9% CP, 66.1% neutral detergent fiber (NDF), and 67.4% in vitro DM digestibility. There was no difference among treatments regarding total diet DM daily intake (21.5, 21.6, and 20.8kg/cow), elephant grass DM (16.1, 16.3, and 15.5kg/cow), and elephant grass NDF (10.7, 10.7, and 10.3kg/cow). Milk yield (17.5, 17.2, and 17.6kg/d) fat (3.4, 3.5, and 3.5%), protein (2.9, 2.9, and 2.9%), lactose (4.4, 4.4, and 4.4%), and N-urea (14.1, 14.6, and 15.8mg/dL) did not differ among concentrates (P>0.05). Plasma N-urea was higher in cows fed concentrate with 21.1% CP (11.5 = 12.2<14.4mg/dL, P<0.05). According to these results, concentrate with 15.2% CP can be used to lactating dairy cows grazing elephant grass, without affecting milk production as compared to concentrate with 18.2 or 21.1% of CP.
A model using concentrations of neutral detergent fiber (NDF), lignin, crude protein (CP), ash, fatty acids or ether extract, and acid and neutral detergent insoluble crude protein, was developed for predicting total digestible nutrients (TDN) of feeds. The model incorporates theoretical digestion coefficients for CP, lipid, and non-fiber carbohydrate. Digestibility of NDF was estimated using a surface area model based on the lignin encrustation theory. The digestible amount of each nutrient was summed and then a term describing metabolic fecal TDN was subtracted. The model was tested on an independent set of 248 feeds (including forages and concentrates). The mean square error for all feeds was 61 g TDN kg−1 dry matter which is comparable with the error term for in vivo digestion data. The model was equally accurate and precise for forages and concentrate feeds.
Avaliou-se o efeito da utilização de concentrados com diferentes teores de proteína bruta (PB) para vacas em lactação sob pastejo rotacionado de capim-elefante, distribuídas em três quadrados latinos (3x3). Os tratamentos foram concentrados suplementares contendo 15,2; 18,2 ou 21,1% de PB. Foram oferecidos 3kg de concentrado por vaca, duas vezes ao dia. A disponibilidade de matéria seca (MS)/ha de capim-elefante foi de 1.873kg ou de 17,4kg de MS/vaca dia-1. A MS do capim-elefante foi de 19,6%, contendo 13,9% de PB e 66,1% de fibra detergente neutro (FDN) e 67,4% de digestibilidade in vitro da MS (DIVMS). Não houve diferença (P>0,05) entre os tratamentos quanto ao consumo diário de MS da dieta total (21,5; 21,6 e 20,8kg/d), MS do capim-elefante (16,1; 16,3 e 15,5kg/d) e FDN do capim-elefante (10,7; 10,7 e 10,3kg/d). As produções de leite (17,5; 17,2 e 17,6kg/d) e os teores de gordura (3,4; 3,5 e 3,5%), proteína (2,9; 2,9 e 2,9%), lactose (4,4; 4,4 e 4,4%) e N-ureia no leite (14,1; 14,6 e 15,8mg/dL) não diferiram (P>0,05) entre os tratamentos (respectivamente, para 15,2; 18,2 ou 21,1% de PB). O teor de N-ureia no plasma foi maior (P<0,05) em vacas alimentadas com concentrado com 21,1% de PB (na ordem citada: 11,5; 12,2 e 14,4mg/dL). Nas condições experimentais, o concentrado suplementar com 15,2% de PB pode ser utilizado na alimentação de vacas em lactação em pastagem de capim-elefante.
Grazing strategies alter sward leaf area patterns of growth, affecting herbage accumulation and utilisation. The objective of this experiment was to evaluate the growth of marandu palisadegrass (Brachiaria brizantha cv. Marandu) swards subjected to strategies of intermittent stocking. The experiment was carried out in Piracicaba, São Paulo, Brazil, from October/2004 to September/2005. Swards were grazed at 95 and 100% canopy light interception (LI) to post-grazing heights of 10 and 15 cm, following a 2 × 2 factorial arrangement with four replications in a randomised complete block design. The response variables evaluated were: crop growth rate, relative growth rate, net assimilation rate, leaf area ratio and leaf weight ratio. In early and late spring, the highest crop growth rate was recorded for treatment 95/15 (11.2 and 10.1 g m-2 day-1, respectively), along with high values of net assimilation rate (4.4 and 6.9 g m-2 day-1, respectively), leaf area ratio (0.0095 and 0.0103 m-2 g-1, respectively) and leaf weight ratio (0.56 and 0.56 g g-1, respectively). To compensate reductions in net assimilation rate plants made some morphological and physiological adjustments increasing leaf area and leaf weight ratio. Relative growth rate and net assimilation rate were 26 and 50% higher, respectively, on swards grazed at 95% than at 100% LI. In early spring treatments 100/10 and 95/15 resulted in the highest relative growth rate (0.086 and 0.059 g m-2 day-1, respectively). Treatment 95/15 resulted in the most favourable pattern of growth (crop growth rate, relative growth rate, net assimilation rate), particularly during the transition period between winter and spring.
Tropical pastures fertilized with nitrogen may have high crude protein (CP) contents with high rumen degradability. High crude protein concentrates offered to cows grazing these pastures may increase feed costs without positive effects on their performance. The objectives of this trial were to evaluate the effects of increasing metabolizable protein (MP) supply beyond the NRC (2001) recommendations for mid lactating dairy cows grazing elephant grass pasture (Pennisetum purpureum Schum. cv. Napier) managed with high stocking rates. Three concentrates (6.3 kg DM-1 cow(-1) day(-1)) were evaluated: control (17% CP) was adjusted in relation to MP according to the NRC (2001); the other two contained extra soybean meal, to increase the CP content to 21.2% (CP) and 25.0% (CP). Twelve multiparous Holstein cows, averaging 150 days of milk production at a rate of 19.5 kg of milk day(-1), were used in a 3 x 3 latin square design, replicated four times. Forage consumption was 11,270 kg DM ha(-1) with 34% of green leaves and 12% CP. Milk production, corrected to 3.5% fat, milk fat, protein, lactose and total solids contents were not affected by treatments (P > 0.05). Milk urea nitrogen and plasma urea nitrogen increased linearly (P < 0.05) as the MP supply increased. Treatments did not affect (P > 0.05) body weight gain, body condition score, grazing time, ruminating time, resting time, rectal temperature and respiratory rate. Crude protein content in the concentrate formulated according to NRC (2001) is adequate for mid lactating cows grazing tropical pastures.
The changes in agricultural policy and the increased concern about the effects of intensive production systems on the natural environment may lead to a reduction in the levels of nitrogen (N) fertilization on grassland. The aim of this review is to quantify the consequences of lowering N fertilization on dairy cow nutrition. For grass species harvested at the same age of regrowth, a reduction in N fertilization leads to a decrease in organic matter (OM) digestibility by 0.02 units, but the site of OM digestion is unaffected. Despite a much lower crude protein (CP) content in poorly fertilized grass, the amount of non-ammonia nitrogen entering the intestine is decreased by only about 5% since the efficiency of microbial protein synthesis is unaffected, while the rumen degradability of CP is slightly decreased. Reducing N fertilization could reduce NEL by 0.3 MJ kg−1 DM and Metabolizable Protein (MP) by 5 to 12 g kg−1 DM. These moderate effects can be attributed to the fact that any decrease in CP content is compensated for by an increase in water-soluble carbohydrates, which are completely digestible and provide a readily available source of energy for ruminal proteosynthesis. Conversely, cell wall content remains unchanged. On average, N fertilization has no effect on the quantity of dry matter voluntarily ingested by stall-feeding animals, but herbage intake at grazing may be reduced since low amounts of N fertilization might reduce the ease of prehension of herbage by reducing the green leaf mass per unit area. Lowering the levels of N fertilization would appear to be an efficient means of reducing N losses in ruminants. The possible consequences on dairy cow nutrition are discussed.
The n-alkanes have been used to estimate forage dry matter intake, digestibility and the diet composition in grazing animals. The objective this study was to compare chromium oxide and n- alkanes techniques used to estimate forage intake. Twenty lactating dual-purpose cows receiving two sources of fat (treatments: conjugated linoleic acid (CLA) or Megalac (control)) plus 4 kg of concentrate were dosed with n-alkanes and chromium oxide to estimate the intake of stargrass (Cynodon nlemfüensis Vanderyst var. nlemfüensis). The in vitro dry matter (DM) digestibility of the stargrass and concentrate were used to estimate the nutritive value of the digesta. The n-alkanes between C23 and C36 were quantified in the digesta and feces. The regression between metabolizable energy requirement (MEr, Mcal d -1 ) and supply derived from forage DM intake estimated using chromium oxide was ME IntakeCr
The aim of this work was to evaluate the effects of in situ incubation time and particles size on the estimates of indigestible fractions of dry matter (iDM), neutral detergent fiber (iNDF), and acid detergent fiber (iADF) in cattle feeds and feces. Samples of corn grain, wheat bran, corn silage, elephant grass, sugarcane, signal grass hay, corn straw, and feces obtained from cattle fed high and low concentrate diets were used. The samples were ground through 1 mm, 2 mm, and 3 mm screen sieve and put in 4 × 5 cm non-woven textile bags (20 mg DM/cm² of surface). The samples were divided in three groups, being each group incubated in the rumen of a crossbred heifer. The incubation procedure was conducted three times with the change of groups among animals. The following incubation times were used: 0, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, and 312 hours. The contents of iDM, iNDF, and iADF were evaluated sequentially in each bag. The degradation profiles were interpreted by a non-linear logistic model. The particles size did not influence the estimates of iNDF and iADF. However, the particles size altered the rumen degradation dynamic rates of DM for corn silage and corn grain; of NDF for sugarcane, corn silage, and corn straw; and ADF for sugarcane. For those samples, the particle size has been positively associated with the incubation time necessary to estimate the indigestible fraction. Incubation times of 240 hours for DM and NDF, and 264 hours for ADF were suggested for obtaining more accurate estimates of indigestible fractions. The use of 2 mm particle size can increase the precision of estimates.
Two experiments were carried out at Mt. Cotton, The University of Queensland, from November 1992 to July 1993, to study the effect of extent of digestion or feed type (grass or legume) on particle kinetics in the rumen. Small (0·5–1·18 mm) Yb-labelled grass or legume particles, either digested or undigested, were injected into the rumen of sheep fed on different diets, and their retention time in the reticulo-ruminal compartment measured. In Expt 1, four intact wethers were fed on either pangola grass hay, chaffed lucerne hay, pelleted lucerne hay or commercial pelleted concentrate. Digested particles from the faeces of animals fed on pangola or lucerne and undigested material from the same diets were wet-sieved and the fraction 0·5–1·18 mm collected, labelled with Yb-acetate and injected into the animals together with a solution of Cr-EDTA. Faecal samples were taken and analysed for marker concentrations. In Expt 2, four similar animals, fitted with duodenal and ruminal cannulae, were fed on different proportions of pangola grass hay and lucerne hay, and Cr-EDTA and the above mentioned labelled particles were injected through the rumen cannula. Samples were taken from the duodenum and analysed for marker concentrations.
The results indicated that diet characteristics rather than extent of digestion or particle type had the greatest influence on rates of passage of both liquid and particulate phases. Different proportions of pangola and lucerne did not result in marked differences in either the volumes of rumen contents or the rates of passage of the solid phase marker but altered the rates of passage of Cr-EDTA. Increasing the proportion of legume increased intake and decreased retention time markedly, with no additive effects on digestibility.
Particles of the same small size escaped with the same fractional passage rate within each diet, irrespective of type (grass or legume) or status (undigested or digested), indicating identical kinetics within each rumen type.
It was concluded that rumen conditions as influenced by diet type have most influence on water and particle kinetics and that extent of digestion of the small particles used in our experiments was not important. Particles of legume or grass of the same size behaved similarly within a diet type.
Forty-eight crossbred lambs (29.0 ± 4.5 kg; 24 ewes, 24 wethers; 1 ewe and 1 wether/pen; 6 pens/treatment) were blocked by BW and randomly assigned to 1 of 4 isocaloric, isonitrogenous treatments containing 0, 15, 30, or 45% crude glycerin (DM basis). Diets, which were offered ad libitum, were primarily composed of 15% chopped hay, 25% dried distillers grains with solubles, and cracked corn, which was replaced with increasing amounts of crude glycerin. Lambs were weighed in 21-d intervals and selected for slaughter when they reached approximately 55 kg of BW. Blood samples were collected on d 57 for analysis of metabolic parameters. Carcass characteristics were collected after a 48-h chill. Days on feed increased linearly (P < 0.001), ADG decreased quadratically (P = 0.02), and both DMI and G:F decreased linearly (P < 0.001) with increasing amounts of glycerin in the diet. Although HCW and LM area did not differ as a result of treatment (P > = 0.31), DP, 12th-rib fat thickness, and LM ether extract all decreased linearly with concomitant increases in glycerin (P < = 0.02). Serum glucose and insulin concentrations decreased linearly with increasing amounts of glycerin in the diet (P < = 0.02), and BHBA concentrations were greater for lambs fed glycerin than those not fed glycerin (P < 0.001). Data from the current study suggest that although feeding up to 15% crude glycerin in the diets of finishing lambs does not differ from feeding no glycerin, feeding 30% or more may have deleterious effects on feedlot performance, carcass quality, and both serum metabolite and hormone concentrations.
Foi avaliado o uso de baixa dosagem de óxido de cromo (Cr2O3) incorporado em um alimento concentrado para estimativa da produção fecal (PF) em bovinos. Para tanto, foram conduzidos quatro ensaios de digestibilidade in vivo utilizando quatro novilhos com peso vivo médio de 214±31kg, recebendo ad libitum no cocho azevém anual (Lolium multiflorum Lam.) cortado verde. Aproximadamente 200g de ração contendo 5g kg-1 do indicador foi fornecida diariamente durante 12 dias, sendo feito a coleta de dados e amostras nos últimos cinco dias de cada período. A PF foi medida com o uso de sacolas de coleção total ou estimada com base na concentração do indicador em amostras fecais coletadas duas vezes ao dia (8 e 16h) ou a intervalos de duas horas entre 8 e 22h. A concentração média de cromo nas amostras coletadas às 8 e 16h (445mg kg-1) foi semelhante à média geral de todos os horários (447mg kg-1). O grau de recuperação fecal (GR) do indicador aumentou linearmente, de aproximadamente 40% para em torno de 80%, com o aumento da concentração fecal de cromo até esta última atingir um valor em torno de 250mg kg-1 de MO. Quando a concentração de cromo nas fezes foi superior a este valor o GR se manteve relativamente constante, em média 76%. A produção fecal foi superestimada pelo indicador em até 35% quando não corrigido para o GR. Quando corrigido para a recuperação fecal, as estimativas de produção fecal de MO estimadas foram similares às observadas. A excreção fecal de bovinos alimentados com azevém pode ser acuradamente estimada com o uso de baixa dosagem de óxido de cromo incorporado em uma ração peletizada concomitante à coleta de duas amostragens diárias de fezes