No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Thermoregulatory responses and ingestive behavior of sheep subjected to water restriction and high-and low-energy diets in a semi-arid environment
Abstract
The aim of the study was to evaluate the effect of water restriction and low-and high-energy diets on sheep's thermoregulatory responses and ingestive behavior. Forty sheep, non-castrated, with an average body weight of 18.85 kg (SD = 2.80 kg) and an average age of 5 months were assigned to a 2 × 2 factorial arrangement, comprising 2 diets (high-and low-energy) and 2 water offers (ad libitum and 50% water restriction), with 10 replicates. Thermoregulatory responses were evaluated in two periods (morning and afternoon). There was an interaction effect of Diet x Water supply x Periods on respiratory rate (P < 0.05). High-energy diets resulted in increased heart rate, idleness, dry matter feeding and rumination efficiency, and water intake. Low-energy diets increased feeding time, rumination time, the number of ruminal cuds, chews per day, total chewing time, neutral detergent fiber intake and rumination efficiency, number of ruminations per day, average duration of rumina-tion, and defecation frequency. Water supply affected heart rate and idleness (P < 0.05). Sheep had higher values of heart rate and rectal and surface temperatures during the afternoon (P < 0.05). Water restriction combined with a low-energy diet and high environmental temperature leads to a reduction in the respiratory rate of Santa Inês crossbred sheep. Regardless of the dietary energy value, water restriction by 50% of the daily requirement of sheep reduces dry matter intake and increases idleness.
ResearchGate has not been able to resolve any citations for this publication.
The aim of this study was to evaluate the intake, digestibility, water balance and growth performance of lambs receiving diets containing cactus silage under an intermittent water supply. Thirty-six male, uncastrated Santa Inês lambs with an initial weight of 19.8 ± 2.1 kg and age of 6 months were distributed in a 3 × 3 factorial arrangement, with three proportions of cactus pear in the diets (0 (control diet containing Tifton hay), 21% and 42% of dry matter) and three periods of intermittent water supply (0, 24 and 48 h), with four repetitions. Lambs that received diets non-isonitrogenous with cactus silage showed higher intakes of dry matter (p < 0.001), total digestible nutrients (p < 0.001), water excretion via faeces (p < 0.001) and water balance (p < 0.001). Lambs that received diets with cactus silage showed higher digestibility of total carbohydrates, non-fibre carbohydrates (p = 0.005), water intake via food (p < 0.001), total water intake (p < 0.001), water excretion via urine (p < 0.001) and water balance (p < 0.05), when compared to the control diet. Lambs that received diets with cactus silage promoted growth performance (p = 0.001). When using 42% forage cactus silage in place of Tifton hay and water offered at 48 h intervals, intake, digestibility, and performance of feedlot lambs were improved.
Simple Summary
Heat stress is a physiological condition where an animal fails to adequately dissipate body heat; this results in increased blood flow in the animal’s core and negatively affects its physiological system. Considering this problem, this study aimed to analyze the reproductive and physiological changes in ewes subjected to heat stress during pregnancy. Twenty-four pregnant crossbred ewes were kept at UTFPR-DV’s (Brazil) silvopastoral (SP) or open pasture (OP) systems throughout their pregnancy. During the experiment, microclimatic variables, sheep’s blood samples, and physiological variables were collected every two weeks. After the birth of the lambs, the placentas were also collected. Our results showed that both systems were stressful for the sheep, but the SP system had lower air and grass temperatures than the OP system. The respiratory and heart rates of animals from the OP system were higher than those from the SP system. As regards the animals’ immune cells, their mobilization was not affected by the systems, while the neutrophil count was only affected by time. Regarding placental biometry, it was observed that placentas in twin pregnancies had a greater membrane area. We concluded that the type of production system used affects the thermal comfort of pregnant ewes; an SP system can offer more amenable microclimatic conditions, which result in greater comfort for the ewes.
Abstract
This study aimed to analyze the reproductive and physiological changes in ewes subjected to heat stress during pregnancy at UTFPR-Brazil. Twenty-four pregnant crossbred ewes were kept in a silvopastoral system (SP) or an open pasture system (OP) throughout the final trimester of pregnancy. Both systems were stressful, but the SP system had lower air temperature than the OP system (26.0 ± 0.38 and 26.9 ± 0.41 °C, respectively; p = 0.0288). Moreover, the radiant thermal load of the two groups presented a difference of 34 Wm⁻² (p = 0.0288), and the grass temperature was also lower in the SP system compared to that in the OP system (23.4 ± 0.37 and 25.6 ± 0.44 °C, respectively; p = 0.0043). The respiratory and heart rates of animals from the OP group were higher than those from the SP group (p < 0.001), but no difference was observed in the mobilization of white blood cells (p = 0.4777), and the neutrophil count was only affected by time (p < 0.0001). As regards placental biometry, placentas in twin pregnancies had a greater membrane area (p = 0.0223), but no differences between the systems were observed in placental weight (p = 0.1522) and the number of cotyledons (p = 0.5457). We concluded that the type of rearing system used affects the thermal comfort of pregnant ewes, and that an SP system can offer more amenable microclimatic conditions, which result in greater comfort for the ewes.
Exploitation of groundwater resources with no proper characterization of water reserves jeopardizes the quantity and quality of water available in the future. A major challenge is finding appropriate methods or coefficients to evaluate the carrying capacity of the aquifer. The objective of this study was to quantitatively and qualitatively characterize water reserves to provide information and management strategies for the rational use of available water resources in an alluvial aquifer in the Brazilian Northeastern semi-arid region. Shallow and medium-depth wells were analyzed. Water tables were monitored in the dry and wet seasons to calculate water reserves. Groundwater samples were collected for the determination of water quality for irrigation purposes. The increase in agricultural activities is jeopardizing the sustainability of the aquifer’s water, as reserves are not sufficient to meet this demand. Groundwater quality is not limiting for agricultural use. Converting surface irrigation into localized methods will potentially increase water productivity and consequently the irrigated area. This study provides data and makes it possible to recommend appropriate strategies for the exploitation of groundwater resources for the maintenance of agricultural activities under semi-arid conditions, and to avoid overexploitation.
Key words:
aquifer overexploitation; need for irrigation; water quality
Water supply is strategic for the development of society. The water distribution in nature follows patterns linked to geographic and territorial issues. Climate fluctuations aggravate shortage problems in semi-arid regions. This study aims to develop a systematic review of research on water scarcity in semi-arid areas through bibliometric methods that allow the analysis of its structure, performance, evolution, and future trends. The methodology considers three phases: (i) literature review, (ii) data cleaning and processing, and (iii) analysis of the research field and future trends. The intellectual structure of water scarcity in semi-arid zones covers 2206 documents with the collaboration of sixty-one countries, distributed in studies carried out in 54 years (1967 to 2021). This field of research has been growing, especially since the 21st century (93.1% of the documents). The countries that study the issue the most are those with high population rates and large consumption patterns, such as the United States and China. There are two central areas of interest led by the terms "water scarcity" and "water stress" due to the intensive use of the resource for agriculture and the management of the water–energy–climate nexus. Thus, the most significant journals studied relate remote sensing to resource management, and the most cited are related to agriculture. This research made it possible to consider future topics such as the study of anthropogenic effects and climate change, the accuracy and applicability of models, and future trends in conventional and unconventional agriculture and resources.
This study aimed to evaluate intake, digestibility, ingestive behaviour, and growth performance of Boer × nondescript breed (NDG) F1, Canindé, and Moxotó kids subjected to three levels of feeding (ad libitum intake and restricted intake by 25 and 50%). The study used 45 non-castrated males, 15 animals from each genetic group, assigned to a 3 × 3 factorial arrangement, with five replicates of each genotypic group at each feeding level. There was an interaction (P<0.05) between genotype and feeding levels for intake, digestibility, and average daily gain (ADG). Boer × NDG F1 kids fed ad libitum had higher dry matter intake (g/day), average daily gain, and lower dry matter digestibility than the Canindé and Moxotó kids. Kids at the 50% restriction level had a longer rumination time per gram of dry matter ingested (0.76 min/g) compared to that fed ad libitum (0.29 min/g) and with 25% restriction (0.41 min/g, P<0.05). Boer × NDG F1 animals, when fed ad libitum, have high growth performance compared to Canindé and Moxotó. Thus, it can be inferred that in feedlot systems with unrestricted feeding and a higher proportion of concentrate than forage (above 50%) in the diet, the use of the Boer × NDG F1 kids is an alternative to increase meat production in the Brazilian semiarid region. When subjected to feed restriction, the growth performance of Boer crossbred kids is similar to that of indigenous breeds. Kids subjected to feed restriction have longer rumination time and higher digestibility coefficients than their counterparts.
Simple Summary
Cow signs are behavioral, physiological, and management parameters that can be observed and measured. Cow signs can be used as a field approach to evaluate the composition of the ration, the quality of rumen fermentation, the quality of digestion, and the general herd health of cattle of interest. This review of cow signs associated with nutrition provides farm advisors, consultants, nutritionists, practitioners, and dairy farmers with an additional toolkit that can be used to improve the assessment of the quality of dairy cattle nutrition. ‘Cow signs’ are not to be used alone as a sole tool for assessment of the quality or nutrition of dairy cows. Some of the ‘cow signs’ are incorporated in precision technologies on many dairy farms and are extensively used in the assessment of dairy cow welfare, health, and nutrition.
Abstract
The aim of this review is to provide dairy farm advisors, consultants, nutritionists, practitioners, and their dairy farmer clients with an additional toolkit that can be used in the assessment of the quality of their dairy cattle nutrition. Cow signs are behavioral, physiological, and management parameters that can be observed and measured. They are detected by examining and observing the cattle. Other physiological parameters such as fecal scoring, rumen fill, and body condition scoring are also included in ‘cow signs’. The assessment should be both qualitative and quantitative; for example, is the cattle individual lame and what is the severity of lameness. The ‘diagnosis’ of a problem should be based on establishing a farm profile of ‘cow signs’ and other relevant information. Information gathered through assessment of cow signs should be used as an advisory tool to assist and improve decision making. Cow signs can be used as part of an investigation and or farm audit.
Aim of study: To evaluate diets with different proportions of butterfly pea hay (BH) and cactus pear meal (CM) on the intake and digestibility of nutrients, productive performance, feeding behavior and physiological parameters of crossbred Boer kids.
Area of study: Northwest of Brazil.
Material and methods: 32 crossbred Boer intact male goats were distributed in a randomized block design, with four treatments with different proportions of BH and CM in the diets, partially replacing elephant grass on a total dry matter (DM) basis: 0% BH + 0 % CM as a control, 83% BH + 17% CM, 67% BH + 33% CM, and 50% BH + 50% CM. Each treatment group included eight animals. The experiment lasted 84 days preceded by 15 days of adaptation.
Main results: Kids fed the control diet had the greatest intake of neutral detergent fiber, hemicellulose, water intake via food, time to feed and the lowest feed conversion (p
Simple Summary
New technologies have been recognized as valuable in controlling, monitoring, and managing farm animal activities. It makes it possible to deepen the knowledge of animal behavior and improve animal welfare and health, which has positive implications for the sustainability of animal production. In recent years, successful technological developments have been applied in intensive farming systems; however, due to challenging conditions that extensive pasture-based systems show, technology has been more limited. Nevertheless, awareness of the available technological solutions for extensive conditions can increase the implementation of their adoption among farmers and researchers. In this context, this review addresses the role of different technologies applied to sheep and goat production in extensive systems. Examples related to precision livestock farming, omics, thermal stress, colostrum intake, passive immunity, and newborn survival are presented; biomarkers of metabolic diseases and parasite resistance breeding are discussed.
Abstract
Sheep and goat extensive production systems are very important in the context of global food security and the use of rangelands that have no alternative agricultural use. In such systems, there are enormous challenges to address. These include, for instance, classical production issues, such as nutrition or reproduction, as well as carbon-efficient systems within the climate-change context. An adequate response to these issues is determinant to economic and environmental sustainability. The answers to such problems need to combine efficiently not only the classical production aspects, but also the increasingly important health, welfare, and environmental aspects in an integrated fashion. The purpose of the study was to review the application of technological developments, in addition to remote-sensing in tandem with other state-of-the-art techniques that could be used within the framework of extensive production systems of sheep and goats and their impact on nutrition, production, and ultimately, the welfare of these species. In addition to precision livestock farming (PLF), these include other relevant technologies, namely omics and other areas of relevance in small-ruminant extensive production: heat stress, colostrum intake, passive immunity, newborn survival, biomarkers of metabolic disease diagnosis, and parasite resistance breeding. This work shows the substantial, dynamic nature of the scientific community to contribute to solutions that make extensive production systems of sheep and goats more sustainable, efficient, and aligned with current concerns with the environment and welfare.
Analyzing the sustainability of grazing livestock farming systems in the drylands at the farm and household or territorial levels (in terms of food security, well-being, value chain performance, feed supply, and maintenance of common grazing resources) constitutes a major challenge in the context of global changes. In particular, social–natural interdependency in an entanglement of spatial and temporal scales complicates the development of a common and systematic framework for assessing the sustainability of these grazing livestock systems. Our objective is to give an overview of some fundamental sets of indicators usually used and elaborate on some principles to guide the sustainable assessment of grazing livestock systems in drylands. To do so, this paper reviews a set of empirical, theoretical, and methodological studies related to the analysis of risk, adaptability, vulnerability, resilience, and sustainability of livestock systems in drylands based on grazing (mostly pastoral systems, but also some integrated crop-livestock systems). More concretely, this review seeks to compile a set of indicators to inform the processes of assessing the sustainability of livestock socio-ecosystems.
It points to the wide range of approaches that have been used to address the sustainability of grazing livestock systems, ranging from those that focus on ecological or social approaches to more integrated and systemic approaches; from indicator-based approaches to those focusing on processes; from quantitative approaches to those that point out the need to take qualitative aspects into consideration; and from research-based assessments to participatory approaches. Based on this review, we propose a multi-scale indicators framework combining scales of space, time, and coordination to address the sustainability of these livestock systems. This framework aims to constitute a sound basis for elaborating a system of information that will contribute to and support policymakers and development agencies in developing their policies and measurements in order to ensure the sustainable development of pastoral and agropastoral systems in the short and medium-term. However, this study also warns about the multiple contextual scopes of the indicators and their implications, which reveal differing dynamics (and therefore adaptive capacities) of these systems.
This study aimed to evaluate the microbiological composition of cactus pear-based diets with increasing levels of buffel grass hay, and its effect on the blood and physiological parameters and occurrence of diarrhea in feedlot sheep. Four diets containing different percentages of buffel grass hay were tested. Diets were composed of forage cactus, buffel grass hay and concentrate, and the treatments were represented by different levels of hay in the dry matter of the feed: 7.5% buffel grass hay; 15% buffel grass hay; 30% buffel grass hay; and 45% buffel grass hay on a dry matter basis. There was a significant effect (p = 0.0034) of inclusion levels of buffel grass hay on fecal score. Only at the 45% inclusion level diarrhea was not observed, showing that the level of buffel grass affected more the animals than the collection period, although the collection period has affected the microbial counts. Probably there was a physiological adaptation of animals over time. There were significant changes (p < 0.0001) in the blood parameters of sheep. The reduction of the proportion of cactus and the inclusion of greater than 15% buffel grass hay, on a dry matter basis, provides less contamination of the diet and animal feces by enterobacteria, such as E. coli.
The supply of drinking water to the population is an important challenge facing humanity, since both surface and underground sources present a great variability of water storage with respect to space and time. This problem is further aggravated in arid and semi-arid areas where rainfall is low and torrential, which makes groundwater the main source of supply; therefore, it is necessary to carry out studies that allow evaluating the evolution of the quantity and quality of water. This study addresses the behavior of groundwater in a semi-arid region, considering the theory of flow systems to identify movement as well as water quality, es determined by a water quality index (WQI), calculated considering arsenic and fluorine. In addition, a quality irrigation classification is used, employing the norms in accordance with international standards and the Mexican Norm, which allows for a comparison. Local, regional, intermediate and mixed flow systems are identified, and the evolution of cations and anions in addition to temperature is examined. It is observed that the drinking water quality index classifies them as excellent in most of the monitored wells (<50), but with a negative evolution. Regarding irrigation, most of the water samples are classified without restriction for the establishment of any type II crop (C2S1) and with restrictions for horticultural crops. It is observed that arsenic had values between 0.49 and 61.40 (µg/L) in 2005, while in 2015 they were between 0.10 and 241.30 (µg/L). In addition, fluoride presented values between 0.00 and 2.6 (mg/L) in 2005, while in 2015 they were between 0.28 and 5.40 (mg/L). The correlations between arsenic and fluorine are noted as well as WQI and SAR. A finding in this research was to include arsenic and fluorine in the calculation of the WQI allowing a better interpretation of the quality of water for both human consumption and for agricultural use to based on this make the best decision to control any harmful effects for the population, in addition to identifying the appropriate purification treatment required to control pollutants. It is concluded that arsenic is an element of utmost importance when considering water quality, so it is necessary to examine its evolution and continue to monitor its levels constantly.
In arid and semi-arid environments, extensively managed ruminants regularly experience drinking water shortage, especially in the dry season. The present study therefore investigated the effects of mild drinking water restriction on feed intake, feed digestibility, solid digesta passage and composition of faeces including faecal microbial biomass. A feeding trial was conducted in Oman, during the dry summer months.
Nine adult male Batinah goats were subjected to three watering regimes in a 3 × 3 Latin Square design. Treatments were (1) water offered ad libitum (100%, W100); (2) water restricted to 85% ad libitum consumption (W85); and (3) water restricted to 70% ad libitum consumption (W70). Animals were offered Rhodes grass hay and whole barley grains (1:1 ratio) at 1.3 times maintenance energy requirements. Each of the three experimental periods comprised 16 days of adaptation and 8 days of measurements. During the latter, feed offered and refused as well as faeces were sampled and quantified. Gastrointestinal digesta passage was determined using ytterbium-labelled Rhodes grass hay. Ergosterol and amino sugars were used as markers for faecal microbial biomass, that is the sum of fungi and bacteria. Water restriction had no effect on feed intake and digesta passage. However, feed dry matter, organic matter and fibre digestibility increased (p < 0.05) in W70 compared with W85, and the excreted amount of faecal dry matter, organic matter, nitrogen and neutral detergent fibre decreased (p < 0.05) in W70 compared with W85. Even though water restriction did not affect total faecal microbial biomass carbon (C) concentration, that of fungal biomass C increased (p < 0.05) in W70 compared with W85. Therefore, mild water restriction seems unproblematic from a physiological and nutrient utilization perspective as it increases feed digestibility without compromising feed intake.
For decades, the principles of genetic improvement have been successfully applied in the production of different livestock species. This success is largely due to the development of statistical methods, computational tools and molecular biology. In general, the production chains which have invested the most in genetic improvement are the ones that developed the most and are providing the greatest economic return today. Sheep farming represents one of the main livestock activities responsible for the production of animal protein in the world. However, most of the sheep flocks, mainly in developing countries, still do not participate in breeding programs. As a result, the economic potential that the sheep farming may achieve is less used, once the growing demand for sheep farming products are coming from consumers of different cultures and social levels. In Brazil, the Santa Inês native sheep breed is considered to have the greatest potential to meet the demands of the consumer market for quality and quantity of sheep meat. This breed has attributes that set it apart from other native and exotic breeds raised in the country. However, due to the low structure of the Brazilian sheep industry and the lack of sheep breeding programs in Brazil, the sheep meat production in the country is insufficient even to meet the domestic demand. In an attempt to solve this situation, several initiatives have already been taken, in particular, within the scope of research. Those initiatives represent efforts to promote the production of sheep meat using native genetic resources, with emphasis on the Santa Inês breed. However, there is still a need for greater investments on the part of the competent authorities, researchers and producers in order to enable the practical application of the results of the research, especially those focused on the genetic improvement of sheep flocks.
Feeding behavior analysis provides information about the relationships between animals and pastures. Therefore, this review aims to describe some aspects of the feeding behavior profiles of both sheep and goats in grazing systems. The structure of the pasture is a key factor in the feeding behavior of grazing animals. The amount of feed consumed in a given period of time is affected by the number of meals, duration and velocity of swallowing, changes in grazing time, bite rate, bite weight, and quality of ingested forage. The different phenological stages of forage also influence the animals' strategies to optimize their intake, which consequently changes their behavioral activities. Sheep and goats tend to be more selective than cattle, and young animals are more selective than older animals; this selectivity characteristic is one of the most important aspects to be observed in pasture management. According to the degree of selectivity, the animals will intake forages of higher or lower nutritive quality. In addition, the intensity and distribution of their daily activities (grazing, ruminating, and resting) are influenced by several factors, such as the availability and nutritive value of the pasture, its management, the animal activity in the group, and the predominant climatic conditions of the region.
The Santa Inês breed is of great importance for the lamb production chain in Brazil. The adaptive and reproductive characteristics of this breed favor its use in future breeding programs for the production of sheep for slaughter in northeastern Brazil. This study evaluated the carcass characteristics, physical parameters, chemical composition and determination of the fatty acid profile of the lambs of the traditional and modern biotypes, slaughtered at 32 kg and 34 kg. Thirty-six Santa Inês lambs were used, with an average age of 180 days and initial weight of 16 kg in a completely randomized design, with a faecal spruce 2x2 (two biotypes and two slaughtering weights). The data were submitted to analysis of variance and averages were compared by the test F α = 0.05 using SAS GLM, (2011) - Statistical Analysis System, version 9.3.Biotypes and slaughter weight did not influence the physical parameters and the fatty acid profile of the meat. Centesimal composition of meat was influenced by treatments, with the larger contents of meat moisture for the traditional biotype slaughtered at 32 kg, and higher content of ash, protein and fat present in the meat for the modern biotype slaughtered at 34 kg. Santa Inês animals that if frame Modern biotype presents potential for meat production with high nutritional value, due to higher protein content, low fat content and satisfactory amount of oleic, palmitic, stearic, linoleic fatty acids, as well as a great relationship between polyunsaturated acids and saturated.
Simple Summary
Ruminants make important contributions to agricultural production, protein food security, livelihoods, and socio-cultural values, particularly in the developing world. Changing climate has dire consequences on animal agriculture and presents a real challenge for humankind. Increasing temperatures, solar radiation, humidity, and resultant heat waves, low rainfall, and drought compromise the availability of forage and water. These environmental factors adversely affect animal growth and reproduction and increase disease incidence as well as threaten biodiversity. The mitigation of such effects has been confined to location or breeds and is often expensive and not always sustainable in view of continuous variations in the climatic data. In this review we have proposed that genetic selection and breeding of thermotolerant ruminants provide a sustainable means of minimizing the effect of climate change on their production. Given the variation in the ability of ruminants to tolerate heat stress and the availability of genomic tools to pursue this agenda, heat stress can be minimised. This is a shared responsibility, requiring action by stakeholders across all sectors of society.
Abstract
Variations in climatic variables (temperature, humidity and solar radiation) negatively impact livestock growth, reproduction, and production. Heat stress, for instance, is a source of huge financial loss to livestock production globally. There have been significant advances in physical modifications of animal environment and nutritional interventions as tools of heat stress mitigation. Unfortunately, these are short-term solutions and may be unsustainable, costly, and not applicable to all production systems. Accordingly, there is a need for innovative, practical, and sustainable approaches to overcome the challenges posed by global warming and climate change-induced heat stress. This review highlights attempts to genetically select and breed ruminants for thermotolerance and thereby sustain production in the face of changing climates. One effective way is to incorporate sustainable heat abatement strategies in ruminant production. Improved knowledge of the physiology of ruminant acclimation to harsh environments, the opportunities and tools available for selecting and breeding thermotolerant ruminants, and the matching of animals to appropriate environments should help to minimise the effect of heat stress on sustainable animal genetic resource growth, production, and reproduction to ensure protein food security.
The objective of this work was to study the influence of environmental effects, sex of the lamb, type of birth, year of birth, birth season, julian birth date, and lambing weight on the weights and biometric measurements of Santa Inês lambs from birth to weaning (70 days of age), and to define the best-adjusted statistical model. Data on weights, heights, body lengths, and thoracic perimeters obtained at birth and close to 28 and 70 days of age from 270 lambs were used. Three analyses were carried out considering different models; one with isolated environmental factors, one with animals grouped into contemporaries according to lamb sex, type of birth, year of birth, and season of birth (GC1), and one with animals gathered in groups of contemporaries according to lamb sex, type of birth, year of birth, season of birth, and the julian date of birth (GC2). Environmental factors influenced a large proportion of body weights and measurements from birth to weaning; the main factors were type of birth and year of birth. The GC2 evaluations presented higher determination coefficients and lower values for Akaike information criteria. However, many observations were discarded; 114, 111, and 103 compared with those rejected by the GC1 analysis, which included two, three, and four observations at birth, 28 days of age, and at weaning, respectively. This may lead to the exclusion of animals with genetic potential.
A meta-analysis was performed from 66 references retained from a total of 147 ones. The aim was to study the relationship between the THI and some physiologic, metabolic and oxidative responses in sheep. The effects of the breed, physiological state and heat relieving strategies were investigated as well. PCA, GLM, one nested ANOVA and global correlations were used to assess the fixed effects.
Respiration rate, rectal temperature and heart pulse vary significantly in response to THI increase. However, the magnitude of this variance is defined by the breed and the physiological state of the animal. Moreover, Mechanical heat relieving strategies allowed alleviating the drastic effects of hyperthermia on sheep physiologic responses, whereas some nutritional heat abatement strategies increased metabolic heat load and respiration rate. Antioxidant and mineral supplementations were able to protect animals from heat stress.
Environmental-induced hyperthermia reduced feed intake, body weight, circulating glucose and cholesterol levels, and increased lipid and protein catabolism. Significant increase of cortisol hormone was recorded. Indeed, ambient- induced hyperthermia resulted in oxidative stress marked by a decrease of Se contents, enhanced SOD activity, high oxidative stress index, increased protein oxidation, reactive oxygen species production and MDA levels. We report here for the first time that respiration is a second source of free radicals generation in sheep under environmental-induced heat stress.
Heat stress disturbs rectal temperature, respiration and heart rates, exacerbates the post absorptive metabolism as well as the antioxidant status of sheep. Therefore, animals increase their maintenance requirements at the expense of production needs, which become not priorities at all.
Keywords
Heat stressMeta-analysisMetabolismOxidative stressSheep
Simple Summary
Water is one of the most important nutrients to livestock. It is so essential that more than half the volume of the animal's body is water. However, its availability is threatened by the irreversible changes in climate, which has culminated into reduced rainfall in most regions of the world. Such an increasing threat to regular water supply, and by extension to food security and livelihood has forced a shift from large to small ruminant production, especially in regions experiencing low rainfall, with farmers taking advantage of their adaptive process and efficiency of water use. Small ruminants, especially desert goats, can adaptively survive in water-limited areas while trekking long distance in search of feed and they will regain any weight loss at the next watering point. Further research is needed on adaptive indigenous breeds of small ruminants since tolerance to water scarcity is breed dependent, so that improvements can be made through effective selection and breeding program.
Abstract
The availability and sustainability of suitable and good quality drinking water is a global concern. Such uncertainties threaten livestock production with an attendant ripple effect on food security. Small ruminants, including sheep and goats, appear to be promising to smallholder farmers in solving this problem because of their ability to survive in water-limited areas and harsh environment when compared with large ruminants. Their small body size is also seen as an advantage, because less water will be required for proper digestion and feed utilization. Therefore, this review will provide information regarding the adaptive responses of small ruminants on thermoregulation, blood metabolites, immune status, drug pharmacokinetics, reproduction and hormonal indices during the period of water stress. Adaptable and indigenous breeds are known to be more tolerant to water stress than selected breeds. A drop in feed intake and weight reduced respiratory rate and increased concentration of blood metabolites are the general effects and/or observations that are encountered by small ruminants during the period of water stress. The concept of water tolerance either as deprivation and/or restriction of indigenous and adaptable breeds of small ruminants is gaining ground in research studies around the world. However, more research, however, seeking to explore water tolerance capacity of adaptable breeds especially in arid and water limiting areas are still needed.
Simple Summary
Heat events during summer can result in dramatic reductions in milk production in grazing dairy cows as they attempt to reduce their accumulated heat load. Therefore, there is interest in dietary manipulations that can decrease heat production or increase heat dissipation. One of the actions of sugar beet-derived betaine is to act as an osmolyte and reduce intracellular ion pumping and heat production. Therefore, this study was conducted to investigate the effects of dietary betaine supplementation on milk and milk component production in grazing dairy cows during hot periods in summer.
Abstract
Betaine is an organic osmolyte sourced from sugar beet that accumulates in plant cells undergoing osmotic stress. Since the accumulation of betaine lowers the energy requirements of animals and, therefore, metabolic heat production, the aim of this experiment was to investigate if betaine supplementation improved milk yield in grazing dairy cows in summer. One hundred and eighteen Friesian × Holstein cows were paired on days in milk and, within each pair, randomly allocated to a containing treatment of either 0 or 2 g/kg natural betaine in their concentrate ration for approximately 3 weeks during February/March 2015 (summer in Australia). The mean maximum February temperature was 30 °C. Cows were allocated approximately 14 kg dry matter pasture and 7.5 kg of concentrate pellets (fed in the milking shed) per cow per day and were milked through an automatic milking system three times per day. Betaine supplementation increased average daily milk yield by over 6% (22.0 vs. 23.4 kg/day, p < 0.001) with the response increasing as the study progressed as indicated by the interaction (p < 0.001) between betaine and day. Milk fat % (p = 0.87), milk protein % (p = 0.90), and milk somatic cell count (p = 0.81) were unchanged by dietary betaine. However, betaine supplementation increased milk protein yield (677 vs. 719 g/day, p < 0.001) and fat yield (874 vs. 922 g/day, p < 0.001) with responses again being more pronounced as the study progressed. In conclusion, dietary betaine supplementation increased milk and component yield during summer in grazing dairy cows.
The objective of this work was to estimate genetic parameters for traits related to resistance to endoparasites in Santa Inês sheep, for a possible inclusion in sheep breeding programs, as well as to evaluate the additive genetic pattern of the animals using cluster analyzes, in order to assess whether there are groups within the population that can be used as candidates for selection for resistance to endoparasites. The studied traits were: Famacha score, fecal egg counts (FEC), packed cell volume (PCV), total plasma protein (TPP), body condition score (BCS), and body weight (BW). Heritability estimates ranged from 0.17 (0.05) for TPP to 0.31 (0.07) for BCS. The cluster analyzes based on the breeding values identified four clusters. Famacha and BCS can be recommended as selection criteria for resistance to hematophagous endoparasites because they can respond to selection and are easy to be measured. Animals from cluster 1 have great potential as candidates for selection because of their additive genetic pattern, taking into account body weight and endoparasite resistance due to higher breeding values for BW, BCS, PCV, and TPP and lower breeding values for Famacha and FEC.
This study aimed to assess the effect of using forage cactus silage in the diet of sheep under intermittent water supply on its ingestive behavior and thermoregulation. We used in the experiment thirty-six intact male sheep of undefined genotype with an initial average weight of 19.8 ± 2.1 kg and age of approximately six months. The experimental design was a randomized block design in a 3 × 3 factorial scheme composed of three levels of forage cactus silage in the diet (0, 21, and 42%), three water supply periods (0, 24, and 48 hours), and four replications. For the ingestive behavior, observations were carried out every 5 minutes for 2 periods of 24 hours. Thermoregulatory responses were taken at 7:00 and 15:00 h on days other than those intended for ingestive behavior tests. Intermittent water supply did not affect any of the studied variables (P > 0.05). The use of forage cactus silage significantly influenced the ingestive behavior of animals (P < 0.05). Sheep fed forage cactus silage in the diet presented an average feeding efficiency of 255.77 g DM h?1 and an average rumination efficiency of 102.16 g DM h?1, while animals fed control diet showed values of 198.63 and 78.45 g DM h?1, respectively. Urinary frequency increased according to the levels of forage cactus silage in the diet, with 23.60 urination per day in animals fed diets with 42% of forage cactus silage and 10.83 urination per day in animals fed control diet. However, the search for water reduced, with averages of 2.73 and 0.54 per day for animals fed 0 and 42% forage cactus silage, respectively. The use of forage cactus silage also increased thermoregulatory responses of sheep, with an average respiratory rate of 103.35 mov. min?1 and heart rate of 140.08 mov. min?1 in the warmest period of the day (in the afternoon). Thus, sheep fed forage cactus silage increases its feeding and rumination efficiencies, decreases its search for water, and increases its thermoregulatory responses. The intermittent water supply within 48 hours does not influence the ingestive behavior and thermoregulation of confined sheep.
This study aimed to evaluate the physiological responses and adaptability of Anglo-Nubian goat breeds by Ibéria and Benezra tests, maintained in bioclimatic chamber under different temperatures: 20, 24, 28 and 32 °C, where temperature and air relative humidity and black globe humidity index (BGHI) were measured. The design was completely randomized with four treatments and six replicates. With the increase of temperature and the BGHI, increased the surface temperature, the cardiac and respiratory frequency, and the thermal gradient, the rectal temperature remained within normal limits. The adaptability tests indicated that animals in the temperatures of 28 and 32 °C had the physiological parameters altered to maintain the warm-blooded, which BGHI values corresponding were 78.21 and 82.55 respectively, characterizing a warning and danger situation.
Many early studies laid the foundation for our understanding of the mechanics of chewing, the physiological role of chewing for the cow, and how chewing behavior is affected by dietary characteristics. However, the dairy cow has changed significantly over the past decades, as have the types of diets fed and the production systems used. The plethora of literature published in recent years provides new insights on eating and ruminating activity of dairy cows. Lactating dairy cows spend about 4.5 h/d eating (range: 2.4-8.5 h/d) and 7 h/d ruminating (range: 2.5-10.5 h/d), with a maximum total chewing time of 16 h/d. Chewing time is affected by many factors, most importantly whether access to feed is restricted, intake of neutral detergent fiber from forages, and mean particle size of the diet. Feed restriction and long particles (≥19 mm) have a greater effect on eating time, whereas intake of forage neutral detergent fiber and medium particles (4-19 mm) affects rumination time. It is well entrenched in the literature that promoting chewing increases salivary secretion of dairy cows, which helps reduce the risk of acidosis. However, the net effect of a change in chewing time on rumen buffing is likely rather small; therefore, acidosis prevention strategies need to be broad. Damage to plant tissues during mastication creates sites that provide access to fungi, adhesion of bacteria, and formation of biofilms that progressively degrade carbohydrates. Rumination and eating are the main ways in which feed is reduced in particle size. Contractions of the rumen increase during eating and ruminating activity and help move small particles to the escapable pool and into the omasum. Use of recently developed low-cost sensors that monitor chewing activity of dairy cows in commercial facilities can provide information that is helpful in management decisions, especially when combined with other criteria. Although accuracy and precision can be somewhat variable depending on sensor and conditions of use, relative changes in cow behavior, such as a marked decrease in rumination time of a cow or sustained low rumination time compared with a contemporary group of cows, can be used to help detect estrus, parturition, and some illnesses. This review provides a comprehensive understanding of the dietary, animal, and management factors that affect eating and ruminating behavior in dairy cows and presents an overview of the physiological importance of chewing with emphasis on recent developments and practical implications for feeding and managing the modern housed dairy cow.
This review aimed to present the current status of the studies about the role of physiological, hematological, biochemical and hormonal variables on the blood of goats raised in adverse environments. Scientific work in recent years has allowed for the evaluation of how goats of distinct breeds react to edaphoclimatic effects to maintain homeothermy according to adaptability to the environment. The exposure of goats to heat stress causes changes in the physiological functions with impact on production and productivity of the animals. There is evidence that the central nervous system is sensitive to temperature changes, and some cells are agiler in the cold than in heat. In conclusion, we say that regardless of the breed, the raising environment and its climatic variables can trigger physiological, biochemical, hematological and hormonal alterations that result in a reduction of the heat production for maintenance of homeothermy. All these changes have a substantial impact on production and productivity.
This study aimed to describe the population genetic structure and evaluate the state of conservation of the genetic variability of Santa Inês sheep in Brazil. We used pedigree data of the Santa Inês breed available in electronic processing of the Brazilian Association of Sheep Breeders. A file with 20,206 records, which enabled the calculation of the genetic conservation index (GCI), individual inbreeding coefficient (F), change in inbreeding (ΔF), effective population size (Ne), effective number of founders (ƒe), effective number of ancestors (ƒɑ), generation interval (L), average relatedness coefficient of each individual (AR), and Wright’s F-statistics (FIT, FIS, and FST). For pedigree analysis and calculation of population parameters, the program ENDOG was used. The average inbreeding coefficient () was 0.97% and the mean average relatedness () 0.49%. The effective numbers of founders and ancestors were, respectively, 199 and 161. The average values of F and AR increased significantly over the years. The effective population size fluctuated over the years concurrently to oscillations in inbreeding rates, wherein Ne reached just 68 in the year 2012. The mean average generation interval was 5.3 years. The Santa Inês breed in Brazil is under genetic drift process, with loss of genetic variation. It requires the implementation of a genetic management plan in the herd, for conservation and improvement of the breed.
RESUMO Objetivou-se avaliar o desempenho e características de cordeiros Santa Inês e suas cruzas desmamados aos 75 dias de vida e terminados em confinamento. Foram utilizados 30 cordeiros não castrados, 10 Santa Inês, 10 ½Dorper × ½Santa Inês e 10 ¾Dorper × ¼Santa Inês, com idade e peso vivo médio no início do experimento de 82 dias e 19,40 kg, respectivamente. Foi utilizada dieta única contendo 169,0 g/kg de proteína bruta e 2,80 Mcal/kg MS. Não houve efeito do genótipo sobre o desempenho dos cordeiros, exceto para escore corporal final, em que os mestiços Dorper alcançaram os maiores escores. As carcaças dos cordeiros ½Dorper × ½Santa Inês e ¾Dorper × ¼Santa Inês apresentaram maior largura da garupa, área de olho de lombo e percentual de lombo do que as carcaças dos cordeiros Santa Inês. As carcaças dos cordeiros ¾Dorper × ¼Santa Inês alcançaram maior largura do tórax e do anterior quando comparadas com as carcaças dos cordeiros Santa Inês, tendo obtido também melhor conformação e acabamento de carcaça quando comparadas com as carcaças dos demais genótipos. Entretanto, as carcaças dos cordeiros Santa Inês e ½Dorper × ½Santa Inês apresentaram maior percentual de pescoço em relação às carcaças dos cordeiros ¾Dorper × ¼Santa Inês.
The goal of this study was to evaluate the daily rhythmicity of the thermoregulatory responses of Morada Nova ewes that were raised in a semiarid environment. The experiment was conducted during the dry season. Data were collected from 5:00 a.m. to 4:00 a.m.. Samples were taken over the course of 8 days, with a 1-week interval between sampling periods. During each day that the data were collected, animals were measured once an hour for 24 h in an area directly exposed to solar radiation. The environment was characterized by measuring the following variables: air temperature (TA), relative humidity (RH), Black Globe Humidity Index (BGHI), radiant heat load (RHL), and wind speed (WS). Physiological variables that were measured included rectal temperature (RT, °C), respiratory rate (RR, breaths/min), surface temperature (ST, °C), and sweating rate (SR, g m² h⁻¹). We observed that RT, RR, and ST increased as environmental conditions became more stressful. Specifically, environmental conditions became more stressful as RHL, air temperature, and BGHI increased, while RH decreased. All physiological variables of the animals were strongly affected by the time of the day: environmental variables changed drastically between nighttime and noon. Physiological parameters increased sharply from the morning (7:00 a.m.–10:00 a.m.) until noon (11:00 a.m.–2:00 p.m.), except for sweating rate. After noon, these variables began to drop until nighttime (11:00 p.m.–6:00 am), and values of the main physiological indexes were stable during this period. The Morada Nova breed exhibited daily cyclic variations in thermoregulatory responses. Evaporative heat loss mechanisms were triggered during the most stressful times of the day. The first mechanism that animals used was panting, which was an immediate response to environmental heat stress. Cutaneous evaporation had a slower response mechanism to environmental heat stress. Homeothermy conditions were restored to the animals at approximately 5:00 p.m.; however, these findings confirm the importance of providing environmental protection during critical periods of the day, even for locally adapted breeds. These responses suggest that the use of thermal storage allowed the animals to achieve equilibrium with the environment and maintain a stable body temperature.
The aim of this study was to evaluate performance and economic viability of producing sheep fed different levels of roughage, concentrate, and water. Forty Santa Inês crossbred sheep with an average initial weight of 18.85 ± 2.80 kg and an average age of 5.0 ± 2.0 months were distributed in a completely randomized design with a 2 × 2 factorial arrangement composed of two proportions of roughage and concentrate (30:70 and 70:30) and two levels of water supply (ad libitum, and 50% restriction), with 10 replicates. Water restriction had a negative effect (P0.05) feed conversion or feed conversion. Total weight gain, average daily gain, feed conversion, and feed efficiency were influenced by the proportions of roughage and concentrate. In conclusion, the diet with 70% roughage, associated with a water restriction of 50%, reduced the uptake of energy and protein, compromising the animal performance. The combination of the diet plus concentrate and water restricted to 50% of the free consumption provides a better cost-benefit ratio.
Abstract O bem-estar animal é afetado por fatores climáticos que causam influências sobre o conforto térmico, portanto, o objetivo desta revisão da literatura foi avaliar a influência de fatores ambientais sobre as variáveis fisiológicas de animais interessantes zootécnicos. O rendimento é limitado ao stress do animal como resposta ao ambiente onde ele é submetido. A adaptação do animal está ligada à sua condição fisiológica relacionada com a sua zona de sobrevivência, tais como: neutralidade térmica (conforto), zona de hipotermia (estresse pelo frio) e zona de hipertermia (estresse por calor). Variáveis fisiológicas: freqüência respiratória (FR); taxa de sudorese (SR); temperatura rectal (RT); freqüência cardíaca (FC). As variáveis ambientais: temperatura do ar (AT), umidade relativa do ar (AH), de bulbo úmido do índice temperatura do globo (WBGTI) e carga térmica radiante (RTC). As variáveis meteorológicas influenciaram na termorregulação dos animais, afetando seu conforto térmico e diminuindo seu bem-estar. A adaptação das condições que são oferecidas pelo clima da região é um dos fatores responsáveis pelo potencial produtivo do animal.
As an important constituent of animal feeds, fiber represents the portion of feeds that is bulky and difficult to digest. The neutral detergent fiber (NDF) method, developed over 30 years ago, is the method of choice for measuring total fiber in for-ages and other feeds. Several modifications that were made to improve its general applicability to all feeds and others developed in individual labora-tories often resulted in variability among laborato-ries in measuring NDF. The amylase-treated NDF (aNDF) method, therefore, was developed as an ac-curate and precise method of measuring total in-soluble fiber in feeds. A collaborative study was conducted to evaluate the repeatability and reproducibility of the aNDF method over the full range of animal feed materials. Twelve laboratories representing research, feed company, regulatory, and commercial feed testing laboratories analyzed 11 materials as blind duplicates. The materials rep-resented feed matrixes, including animal products; high-protein, high-fat, and high-pectin feeds; oil seeds; grains; heated by-product feeds; and le-gume and grass hays and silages. Materials se-lected varied in chemical composition and con-tained 0–90% aNDF, 1–16% ash, 1–20% crude fat, 1–40% crude protein, and 0–50% starch. Cor-recting results for changes in blanks and reporting results as ash-free aNDF organic matter (aNDFom) improved the repeatability and reproducibility of results when aNDF was <25%. The within-labora-tory repeatability standard deviation (s r) for per-centage aNDFom in feeds varied from 0.21 to 1.82 and among-laboratory reproducibility standard de-viation (s R) varied from 0.37 to 2.24. The HORRAT was <2 for all materials except feed materials con-taining >10% fat. However, standard deviations of repeatability and reproducibility for feeds with >10% fat were similar to those of other materials. It is recommended that the aNDF method be ac-cepted for Official First Action status.
Este trabalho foi realizado com o objetivo de avaliar o uso de sal forrageiro sobre os consumos de sal forrageiro (CSF) e de feno de capim-pangola (Digitaria decumbens) e os consumos de matéria seca (MS), proteína bruta (PB), fibra em detergente neutro (FDN), hemicelulose (HCEL), lignina e água (AGU), além do ganho de peso diário (GPD) e da conversão alimentar de cordeiros em confinamento. Os sais forrageiros foram compostos de farelos de fenos (90%) das dicotiledôneas, sal mineral (5%) e milho triturado (5%). Utilizaram-se 30 animais machos não-castrados, mestiços Santa Inês, distribuídos em delineamento inteiramente casualizado, com seis tratamentos (sal mineral; sal forrageiro de leucena, Leucaena leucocephala; sal forrageiro da parte aérea de mandioca, Manihot esculenta; sal forrageiro de feijão-bravo, Macroptilium bracteatum; sal forrageiro de barriguda, Ceiba samauma; e sal forrageiro de quipé, Piptadenia moniliformis), cada um com cinco repetições. Os sais forrageiros de leucena e da parte aérea de mandioca promoveram melhores resultados de desempenho, ganhos de pesos totais e conversão alimentar, o que evidencia o potencial dessas forrageiras para formulação de sal forrageiro, utilizado na suplementação de dietas para cordeiros em confinamento.
Resumo – O objetivo deste trabalho foi estudar os efeitos de diferentes níveis de farelo de cacau e torta de dendê (0, 15 e 30%) em substituição ao milho e farelo de soja no concentrado, sobre o comportamento ingestivo de cinco cabras Saanen, lactantes, não prenhes, com peso corporal médio inicial de 41,6 kg, alojadas em baias individuais durante cinco períodos experimentais. O volumoso utilizado foi a silagem de milho, em proporção de 40:60 (volumoso:concentrado). Distribuídos em um delineamento em quadrado latino 5x5, os animais foram observados em cada um dos cinco tratamentos, ao final de cada período experimental, durante 24 horas, a intervalos de 10 minutos. Não houve diferença entre os tempos de alimentação, ruminação e ócio. Embora os animais que receberam 30% de farelo de cacau tenham reduzido o consumo de matéria seca (MS), a eficiência alimentar (em g de MS/h e g de FDN/h) foi semelhante em todos os tratamentos. No entanto, a eficiência de ruminação (em g de MS/h e g de FDN/h) e a quantidade de MS e FDN (g/bolo ruminado) foram maiores nos animais com dietas de 30% de farelo de cacau. O tempo total de mastigações (h/dia), o número de bolos rumina-dos (n o /dia), o número de mastigações merícicas (n o /dia e n o /bolo) e o tempo de mastigações merícicas por bolo (s/bolo) não apresentaram diferenças significativas. A inclusão de farelo de cacau ou torta de dendê na dieta influenciou parâmetros do comportamento ingestivo. Termos para indexação: alimentação, descanso, ruminação, subprodutos.
Our objective was to provide a review of factors influencing heat stress in lactating dairy cows and how it affects milk production. In warmer parts of the world, during summer months in the United States, and in other temperate regions, reduced milk production resulting from heat stress counteracts tremendous genetic progress achieved in increasing milk production. Genetic progress in milk production is closely related to increased feed intake. High feed intake results in raised metabolic heat increment. High metabolic heat increment requires effective thermoregulatory mechanisms to maintain body temperature in a thermoneutral zone and in physiological homeostasis. Cows can succumb to hyperthermia if they fail to maintain thermoneutrality. Accurate measurement of when cows enter heat stress is complicated because the responses to heat stress affect not only the energy balance, but also water, sodium, potassium and chlorine metabolism. Water, sodium, potassium and chlorine are important constituents of sweat, and sweating is a major, if not the most important, thermoregulatory mechanism used to dissipate excess body heat. Due to high metabolic heat increment, and especially in the warmer months, high-producing dairy cows may enter heat stress much earlier than their lower-producing counterparts and than currently thought, or extra heat has been accommodated by physiological adaptations. Should this be the case, then strategies to reduce heat stress must be developed to enable cows to express their full genetic potential. The thermoneutral zone, heat production and heat gain, heat dissipation mechanisms, and how the lactating cow responds to heat stress are discussed.
The Cornell Net Carbohydrate and Protein System (CNCPS) has a submodel that predicts rates of feedstuff degradation in the rumen, the passage of undegraded feed to the lower gut, and the amount of ME and protein that is available to the animal. In the CNCPS, structural carbohydrate (SC) and nonstructural carbohydrate (NSC) are estimated from sequential NDF analyses of the feed. Data from the literature are used to predict fractional rates of SC and NSC degradation. Crude protein is partitioned into five fractions. Fraction A is NPN, which is trichloroacetic (TCA) acid-soluble N. Unavailable or protein bound to cell wall (Fraction C) is derived from acid detergent insoluble nitrogen (ADIP), and slowly degraded true protein (Fraction B3) is neutral detergent insoluble nitrogen (NDIP) minus Fraction C. Rapidly degraded true protein (Fraction B1) is TCA-precipitable protein from the buffer-soluble protein minus NPN. True protein with an intermediate degradation rate (Fraction B2) is the remaining N. Protein degradation rates are estimated by an in vitro procedure that uses Streptomyces griseus protease, and a curve-peeling technique is used to identify rates for each fraction. The amount of carbohydrate or N that is digested in the rumen is determined by the relative rates of degradation and passage. Ruminal passage rates are a function of DMI, particle size, bulk density, and the type of feed that is consumed (e.g., forage vs cereal grain).
Effects of prepartum energy intake, replacement of 25% of reticulorumen contents with water-filled bladders, and feeding of polyethylene glycol on DM intake during lactation were assessed in two trials. In trial 1, six rumen-cannulated cows were assigned to diets of either 1.50 or 1.68 Mcal NEL/kg 70 d prepartum. Animals fed the higher energy diet had greater NEL intake and tended to gain more BW prepartum. Intake from 28 to 70 d postpartum was not affected by prepartum diet but was reduced by 24.2 L of bladders placed in the rumen. Milk production tended to be increased for cows fed high energy prepartum and to be reduced by bladders. Total reticulorumen volume, digesta fractional passage rates, and acetate:propionate ratio were increased by bladders. In trial 2, eight rumen-cannulated cows, 28 d postpartum, received polyethylene glycol, 4% of diet DM, and 21.4 L of bladders in the rumen in a 2 x 2 factorial arrangement. Polyethylene glycol did not affect DM intake but reduced DM, CP, ADF, and NDF digestibilities. Bladders increased total reticulorumen volume, rumen fluid pH, and acetate:propionate ratio but decreased DM intake. Intake of DM was reduced .099 kg/L added bulk in trial 1 and .130 kg/L in trial 2. Compensation for replacement of rumen contents with inert bulk occurred by expansion of organ volume and, in trial 1, by a reduction in rumen retention time. These factors may explain why reductions in voluntary intake after addition of inert bulk to the reticulorumen often are proportionally lower than would be predicted from the volume of bulk added.
To further characterize the suppression of feeding that normally accompanies water deprivation and to test whether vasopressin contributes to this hypophagia, food intake, meal patterns and plasma vasopressin concentrations were measured during 24 h or 72 h of water deprivation in pygmy goats. The effects of exogenous vasopressin and of a V1-receptor antagonist on feeding during water deprivation were also assessed. The hypophagia during water deprivation was primarily due to decreases in meal size. The plasma vasopressin concentration increased about 2.5-fold and 10-fold after 24 and 72 h of water deprivation, respectively. Plasma osmolality also increased (measured only after 72 h of water deprivation). Intraperitoneally (ip) injected vasopressin (1.5 micrograms/kg b. wt.) that previously reduced food intake in goats with ad lib, access to water (Meyer et al., 1989), failed to affect cumulative food intake in water deprived goats, but led to a transient increase in meal size. The V1-receptor antagonist (2.5 micrograms/kg b. wt., ip) did not affect cumulative food intake or meal patterns either. These findings indicate that endogenous vasopressin is not crucially involved in the hypophagia during water deprivation. The results are in line with the hypothesis that an abnormal prandial increase in the osmolality of the ruminal fluid is a major contributor to the hypophagia during water deprivation.
Red clover produces isoflavones, including biochanin A, which have been shown to have microbiological effects on the rumen while also promoting growth in beef cattle. The objective was to determine if supplementation of biochanin A via red clover hay would produce similar effects on the rumen microbiota and improve growth performance of lambs. Twenty-four individually-housed Polypay ram lambs (initial age: 114 ± 1 d; initial weight: 38.1 ± 0.59 kg) were randomly assigned to one of three experimental diets (85:15 concentrate:roughage ratio; n = 8 rams treatment -1): CON - control diet in which the roughage component (15.0% w/w of the total diet) consisted of orchardgrass hay; 7.5-RC - red clover hay substituted for half (7.5% w/w of the total diet) of the roughage component; and 15-RC - the entire roughage component (15.0% w/w of the total diet) consisted of red clover hay. Feed intake and weight gain were measured at 14-d intervals for the duration of the 56-d trial, and rumen microbiological measures were assessed on day 0, 28, and 56. Red clover supplementation impacted growth performance of ram lambs. Average daily gains (ADG) were greater in ram lambs supplemented with red clover hay (7.5-RC and 15-RC) than for those fed the CON diet (P < 0.05). Conversely, dry matter intake (DMI) was lower in 7.5-RC and 15-RC than for CON lambs (P = 0.03). Differences in ADG and DMI resulted in greater feed efficiency in ram lambs supplemented with red clover hay (both 7.5-RC and 15-RC) compared to CON (P < 0.01). Rumen microbiota were also altered by red clover supplementation. The total viable number of hyper-ammonia-producing bacteria in 7.5-RC and 15-RC decreased over the course of the experiment and were lower than CON by day 28 (P ≤ 0.04). Amylolytic bacteria were also lower in 15-RC than in CON (P = 0.03), with a trend for lower amylolytic bacteria in 7.5-RC (P = 0.08). In contrast, there was tendency for greater cellulolytic bacteria in red clover supplemented lambs than in CON (P = 0.06). Red clover supplementation also increased fiber utilization, with greater ex vivo dry matter digestibility of hay for both 7.5-RC and 15-RC compared to CON by day 28 (P < 0.03). Results of this study indicate that low levels of red clover hay can elicit production benefits in high-concentrate lamb finishing systems through alteration of the rumen microbiota.
The aim of this study was to evaluate the reduction in water supply (ad libitum intake - 100%, or 80, 60 and 40% of ad libitum intake) on the proximate composition, physicochemical properties, mineral composition and fatty acid profile of ewe meat. Thirty-two crossbred Santa Inês ewe (n = 8 per treatment) were distributed in a randomized block design, receiving a diet consisting of elephant grass and concentrate (70:30). The experimental period lasted 63 days, preceded by 14 days of adaptation. Ewes were slaughtered at the end of experimental period, at a mean final body weight of 37.63 kg. Carcasses were cut lengthwise and the loin (longissimus lumborum) was taken of the left half carcass to evaluate the proximate composition, the physicochemical characteristics, the minerals content and fatty acid profile. The reduction in water supply resulted in a quadratic effect for resilience (p < 0.05), Lightness L* (p < 0.05), potassium (p < 0.05) and iron content (p < 0.001). There was a decreasing linear effect for magnesium content (p < 0.05), copper content (p < 0.001), C18:1n7t content (p < 0.05) and Σmonounsaturated content (p < 0.05). Crossbred Santa Inês ewe tolerate water restriction up to 40% voluntary intake without compromising the meat quality.
The silvopasture is a sustainable livestock system, which has great potential for sheep, mainly focused on the thermal comfort and welfare of animals. However, there is a lack of information regarding the thermal environment and physiology of ewes and lambs raised in this system. This study was therefore aimed at assessing the influence of microclimate on the thermal comfort of postpartum ewes and lambs kept in silvopastoral (SP) or open pasture (OP) systems during the summer. Postpartum crossbred ewes (Santa Inês x Dorper; n = 24) and their lambs (n = 24) were randomly allocated to SP or OP group, being distributed into four paddocks per group (three ewes and three lambs per paddock). The microclimate characterization measured were dry-bulb ambient temperature (Ta, ºC), black globe temperature (Tbg, ºC), relative humidity (RH, %), grass temperature (Tg, ºC) and wind speed (WS, m s⁻¹). These variables were then applied to calculate the temperature and humidity index (THI), black globe temperature and humidity index (BGHI), and radiant heat load (RHL). To assess the thermophysiology response, the respiratory rate (RR, breaths min⁻¹), heart rate (HR, beat min⁻¹), rectal temperature (RT, ºC), and hair coat surface temperature (ST, ºC) were analyzed. Regarding the microclimate variables, Ta and Tg were higher in OP than in SP (P = 0.008 and P < 0.001, respectively), while SP presented higher RH values (P = 0.037). There was no significant difference in WS between the systems (P = 0.288). As expected, all indices showed lower mean values in SP compared to OP, mainly the radiant heal load (P < 0.001). Regarding the thermophysiology response, the RR of ewes was significantly higher in OP (129 ± 4.5 breaths min.⁻¹) than in SP (85 ± 4.7 breaths min.⁻¹) (P < 0.001). The RT was higher in the OP, but only in the afternoon (P < 0.001). Meanwhile, lambs in OP also presented higher RR (105 ± 3.5 breaths min.⁻¹) and RT (39.9 ± 0.1 °C) values than in SP (74 ± 2.8 breaths min.⁻¹ and 39.9 ± 0.1 °C, respectively). Following the prior trends, during the afternoon lambs showed higher values of RR than in the morning. However, the difference between those periods was small for RT. The ST of ewes in SP was lower compared to ewes in OP (P < 0.001). In the afternoon, the difference of ewes in SP had ST 4.3 °C lower compared to OP, while for lambs, the ST in the afternoon increased by 5.3 °C more in OP than in SP. The study suggests that the presence of trees reduced hyperthermia for both ewes and lambs further supporting the SP as a sustainable farming system that promotes thermal comfort and welfare for small ruminants.
The aim of this study was to evaluate the effect of reducing water supply for watering of Santa Inês ewes on carcass characteristics, non-carcass components and the volume of digestive compartments. Thirty-two crossbred Santa Inês ewes, with an average body weight of 32.2 ± 7.4 kg, were distributed in a randomized block design with four treatments (different supply levels - 100% (ad libitum), 80%, 60% and 40% ad libitum water intake treatment) and eight repetitions. The animals were confined for 63 days until slaughter. The decrease in water availability promoted a linear decreasing effect for the internal carcass length (P=0.032). A quadratic effect was found for the volume of the omasum (P = 0.018) and abomasum (P = 0.039), with maximum volumes of 0.305 and 1.636 liters, respectively, for 40% supply. The reticulum yield showed a quadratic effect (P = 0.044) with a maximum point in the supply of 100%, with 0.527%. The reduction in water supply promoted a quadratic effect for the weight (P = 0.016) and yield (P = 0.030) of the bladder, with maximum yields found in the supply of 60%, with 0.067 kg and 0.233%, respectively. There was a quadratic effect for weight (P = 0.042) and yield (P = 0.029) of the diaphragm with higher values found in the supply of 60%m with 0.272 kg and 0.927%, respectively. There was a quadratic effect for kidney yield (P = 0.022) with higher yield for 100% supply. Therefore, the reduction in water supply levels by up to 40% in relation to voluntary intake can be a strategy to be used in cases of water scarcity, as it does not cause negative effects on the Santa Inês ewe carcass.
In this work, the influence of the addition of Tifton-85 hay supplement to the corn grain mix and commercial pellet was assessed in terms of the digestive behavior exhibited by the dairy calves. The Latin square 4 x 4 duplicate and simultaneous design was adopted in this experiment, in which the treatments included four levels of the hay supplement Tifton-85 (0, 0.2, 0.4, and 0.8 %) with respect to body weight, in the corn grain mix and commercial pellet, over four experimental periods, with two repetitions (eight animals). The effect of the hay levels (P < 0.05) was evident in the time taken by the animals for feeding (TFE), rumination (TRU), and total chewing time (TCT), however, the time spent in leisure (TO) remained unaffected (P > 0.05). The variables, chew time per bolus (CT/bolus), and number of chews per bolus (NC/bolus) showed no differences among the treatments (P > 0.05), however, the number of chews per day (NC/day), and number of ruminal boluses (NRB) revealed significant variations (P < 0.05). Among the treatments, the effects on feed efficiency (EFDM) and rumination (ERUDM) of dry matter (P < 0.05) were evident, but the rumination efficiency of the neutral detergent fiber (ERUNDF), and rumination rate (RR) were not affected (P > 0.05). The supplementary levels of hay added to the diet increased the rumination and chewing times.
The current study evaluated the effects of dietary roughage:concentrate (R:C) ratios and water supply on the carcass characteristics and yield of lambs. Forty Santa Inês crossbred lambs with an average body weight (BW) of 19 ± 2.8 kg were evaluated in a completely randomized design with a 2 × 2 factorial arrangement consisting of two proportions of roughage and concentrate (30:70 and 70:30) and two levels of water supply ( ad libitum and restricted to 0.5). The animals were slaughtered at an average weight of 28 ± 31 kg. Centesimal composition, colour parameters (L*, a* and b* ), shear force, cooking losses and pH were determined on the Longissimus lumborum muscle. There was no interaction effect between the R:C ratio and water supply on the evaluated variables. Total BW gain, average daily gain and final BW were affected by water restriction and R:C ratio. Water restriction reduced total BW gain, average daily gain and final BW. No effect of water restriction was detected on slaughter weight, centesimal composition, colour variations, shear force, pH, weight or yield of carcass. No effect of water restriction and diets was observed on the cuts, except for neck weight. Carcass weight and yield were affected by the R:C ratios. Restricting the water supply to 0.5 does not affect the carcass weight or yield of Santa Inês crossbred lambs or their meat quality characteristics (centesimal composition, colour, shear force and pH measurements). A higher proportion of concentrate in the diet results in heavier hot and cold carcass weights.
• Historically, drinking water for ruminants has been a relatively inexpensive and abundant resource, but this is changing in both developed and developing countries. • Despite the great amount of attention paid to other essential nutrients by animal scientists and livestock farmers in the last century, water nutrition and water quality have not been adequately examined. Even today, drinking water is seldom considered a potentially limiting factor for the productivity and health of ruminants. Farmers rarely have information about the 2 major initial factors for assessing the adequacy of water nutrition on any farm: how much the animals are drinking and what the quality of that water is. • Although livestock will never rival humans for the world's supply of potable water, they do use large amounts in some production systems. Nonetheless, ruminants also hold a unique niche in the production of food and other tangibles for humans by their ability to consume fibrous and lower quality feedstuffs (e.g., forages and by-products) not utilizable as food directly by humans and other nonruminants, and to convert these feeds into highquality proteins, vitamins, fats, and energy for humans. This unique capacity of ruminants very much depends on sufficient quantities of water for maintenance, digestion, absorption, and assimilation. • Should potable drinking water become scare in some areas of the world, domestic ruminants may be forced to consume poorer quality water containing anti-quality factors. If we are to sustain the increasing demand for animal products and improve the standard of living globally, the conservation and recycling of clean drinking water on ruminant farms will be critical. Otherwise, the only alternative may be widespread use of water treatment systems. • Doubtless, ruminant farmers must improve their management by carefully using and conserving the available clean water for their animals. The future viability of ruminant production systems depends on it. Through more efficient use of water, farmers can maximize animal performance and health while simultaneously optimizing on-farm use (from irrigation for feed crop production through recycling and conservation) to reduce the water footprint of each farm.
The environment within which domesticated livestock production, agricultural crops and related management practices developed over the past 10,000 years is rapidly changing due to human-induced climate change (CC). Nowadays, even countries located within the temperate zone are affected by changes in global warming. These changes are associated with unprecedented events of extreme high ambient temperature (above 40 0C) and seasonal changes. The number of days with temperature humidity index (THI) above a specific comfort threshold (> 68) has noticeably increased in recent years in European countries located within the temperate zone. The rate of global warming, including in the temperate zone, is expected to continue to vulnerable in coming years. Agricultural production from crops and livestock, and thus global food security, is already affected by CC and will continue to be influenced by global warming. Thus, these changes will continue to affect the dairy industry directly and indirectly. The most significant indirect effect is expected to result from cruel reduction in worldwide grains (concentrate feedstuffs) production. This change will impose need to tradeoff between the diminished food sources: using higher proportions of grains production for human nutrition, instead of feeding it to livestock. Similar conflict is expected to be relevant in using high-quality forages that can be used as edible food for humans. Heat stress imposed by high ambient temperature in temperate zones, such as in Germany, northern Italy and the US was identified in recent years as a major factor that affect negatively, milk production, reproduction, and the health of dairy cows. Heat stress also has shown to increase appreciably cow's mortality in those areas. On the other hand, there is no evidence that dairy goat production in temperate zones is affected so far; though, evidence for such an effect was notice in desert and Mediterranean (e.g., Turkey) countries. The major aim of this critical review is to analyze the literature in order to predict how the current trend in harshening of the impact of climatic changes affect dairy industry and to forecast how CC will affect the dairy cows and goat industry in countries located within the temperate zone? Particularly, the direct effects of heat stress on milk production are emphasized. Among domestic ruminants, goats are the most adapted species to imposed heat stress in terms of production, reproduction and resistance to diseases. The main conclusion that can be made is that uttermost scenarios of climatic change will negatively affect the dairy industry and that the importance of goats to the dairy industry will increase in proportion to the severances of changes in environmental temperature.
The purpose of the present review is to provide an integrated examination of the effects of infrequent drinking, water restriction, and heat load on feed intake and utilization in ruminants. The above-mentioned limitations reduce appetite and increase feed utilization. Reduction in rumen motility, rumination activity and saliva secretion reduce passage rate, and hence increase the digestibility of structural carbohydrates. However, contrary to a commonly held view, these digestive responses are directly related to the imposed stress, rather than secondarily related to reduction in feed intake. Although water deprivation, water restriction and heat load similarly affect appetite and digestion, the physiological basis of each is different. Water restriction does not disturb plasma tonicity and its effect is mediated by modification of the food-related drinking. Water deprivation effects are mediated through elevation of plasma osmolarity and secondarily through increase in gut fill and ruminal Na concentration. Heat load effect is mediated through elevation of body temperature and secondarily through increase in gut fill. The response to heat stress is more diverse, since heat load affects both the energy and water metabolism, and varies due to differences among ruminants in insulation properties and body size. As water scarcity and high temperatures are characteristic of dry areas, interactions exist between these two factors, and some examples are given. Goats, having poor insulation capacity, and sheep, with excellent insulation capacity, represent two physiological models. Breeds of ruminants which are well adapted to arid environments demonstrate a greater capability than non-desert breeds to ameliorate the stressful effects induced by water deprivation and heat load. However, as a general rule, the negative effects of water deprivation and heat stress override the benefits from increased feed utilization.
Nonfiber carbohydrates (NFC) encompass a compositionally and nutritionally diverse group exclusive of those carbohydrates found in NDF. Their content in feeds has often been described as a single value estimated by difference as 100% of dry matter minus the percentages of CP, NDF (adjusted for CP in NDF), ether extract, and ash. A calculated value was used because of difficulties with assays for individual NFC, but it does not differentiate among nutritionally distinct NFC. Errors in NFC estimation can arise from not accounting for CP in NDF and when multipliers other than 6.25 are appropriate to estimate CP. Analyses that begin to distinguish among NFC are those for starch, soluble fiber (non-NDF, nonstarch polysaccharides), and low molecular weight carbohydrates (mono- and oligosaccharides). Many starch analyses quantify alpha-glucans through specific hydrolysis of alpha-(1 --> 4) and alpha-(1 --> 6) linkages in the glucan, and measurement of released glucose. Incomplete gelatinization and hydrolysis will lead to underestimation of starch content. Starch values are inflated by enzyme preparations that hydrolyze carbohydrates other than alpha-glucan, measurement of all released monosaccharides without specificity for glucose, and failure to exclude free glucose present in the unhydrolyzed sample. Soluble fiber analyses err in a fashion similar to NFC if estimation of CP requires multipliers other than 6.25, or if contaminants such as CP and starch have not been properly accounted. Depolymerization and incomplete precipitation can also decrease soluble fiber estimates. The low molecular weight carbohydrates have been defined as carbohydrates soluble in 78 to 80% ethanol, which separates them from polysaccharides. They can be measured in extracts using broad-spectrum colorimetric assays (phenol-sulfuric acid assay or reducing sugar analysis of acid hydrolyzed samples) or chromatographic methods. Limitations of the colorimetric assays include lack of differentiation among mono- and oligosaccharides and differences in efficacy of measuring total carbohydrate. More sensitive and precise chromatographic methods require expensive equipment and specialized expertise. Current methods for NFC can separate nutritionally relevant fractions, but questions remain as to which fractions merit analysis and what analyses to use. These issues must be resolved in order to soundly evaluate and explore the roles of carbohydrates in diets.