Heat Stress in Livestock: Impacts and Ameliorative Strategies—a Review (original) (raw)
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Physiological adaptability of livestock to heat stress: an updated review
Journal of Animal Behaviour and Biometeorology, 2018
Climate change associated heat stress was established to be the crucial factor, which negatively influences animal production. The animals possess several adaptive mechanisms which are helpful for their survival in harsh environmental conditions, but while doing so their productive performances are compromised. Among the various mechanisms, which helps to maintain homeostasis in animals, Physiological adaptability was considered one of the primary response mechanisms by which the heat stressed animals survive the heat stress. This review is therefore an attempt to provide the audience an updated review on the subject to signify the importance of physiological responses in animals and their role in surviving the stressful environment. Respiration rate (RR), pulse rate (PR), rectal temperature (RT), sweating rate (SR) and skin temperature (ST) are the cardinal physiological variables which helps to maintain the heat balance and homeostasis in the stressed animals. Among the various physiological variables, RR, RT and ST were established to be ideal indicators for quantifying heat stress in several farm animals. Therefore, these variables can be effectively used to assess the severity of heat stress in livestock. Although these variables are considered significant in establishing the heat stress impact in animals, a wide genetic variation was also established in these response mechanisms. Further, variations in physiological adaptability were also established between indigenous, cross bred and pure bred animals. The indigenous livestock breeds were tipped to be exhibiting less physiological variability as compared to their counterparts. These discussions vividly indicate the importance of studying in detail the physiological adaptive mechanisms in different farm animals and these efforts can help the farming community to identify the suitable agroclimatic zone specific livestock breeds which can go in long way to help to ensure climate resilient livestock production.
Adaptation to hot climate and strategies to alleviate heat stress in livestock production
animal, 2012
Despite many challenges faced by animal producers, including environmental problems, diseases, economic pressure, and feed availability, it is still predicted that animal production in developing countries will continue to sustain the future growth of the world's meat production. In these areas, livestock performance is generally lower than those obtained in Western Europe and North America. Although many factors can be involved, climatic factors are among the first and crucial limiting factors of the development of animal production in warm regions. In addition, global warming will further accentuate heat stress-related problems. The objective of this paper was to review the effective strategies to alleviate heat stress in the context of tropical livestock production systems. These strategies can be classified into three groups: those increasing feed intake or decreasing metabolic heat production, those enhancing heat-loss capacities, and those involving genetic selection for heat tolerance. Under heat stress, improved production should be possible through modifications of diet composition that either promotes a higher intake or compensates the low feed consumption. In addition, altering feeding management such as a change in feeding time and/or frequency, are efficient tools to avoid excessive heat load and improve survival rate, especially in poultry. Methods to enhance heat exchange between the environment and the animal and those changing the environment to prevent or limit heat stress can be used to improve performance under hot climatic conditions. Although differences in thermal tolerance exist between livestock species (ruminants . monogastrics), there are also large differences between breeds of a species and within each breed. Consequently, the opportunity may exist to improve thermal tolerance of the animals using genetic tools. However, further research is required to quantify the genetic antagonism between adaptation and production traits to evaluate the potential selection response. With the development of molecular biotechnologies, new opportunities are available to characterize gene expression and identify key cellular responses to heat stress. These new tools will enable scientists to improve the accuracy and the efficiency of selection for heat tolerance. Epigenetic regulation of gene expression and thermal imprinting of the genome could also be an efficient method to improve thermal tolerance. Such techniques (e.g. perinatal heat acclimation) are currently being experimented in chicken.
Veterinaria México OA, 2022
Heat stress induces failures in the physiological mechanisms that regulate the body temperature of farm animals and causes a loss in their productive and reproductive potential. Thus, we performed a scoping review to systematically map, describe, and classify primary research that assessed the effect of heat stress on the reproductive, physiological, and productive parameters of livestock. Electronic databases were searched to retrieve full text, peer-reviewed experimental or cohort studies published from 1980 to August 2018. We included in vivo and in vitro studies exposing animals or cells to heat stress conditions and used a control group. Studies were evaluated based on title and abstract and then selected for final inclusion based on full text. We performed data charting to describe and visualize the evidence. In total, we included 466 studies, among which bovines and pigs were the most frequent species studied. Reproductive and physiological parameters were the main groups of outcomes assessed, and studies using adult females predominated. Seventy percent of the studies were experimental, and almost half of the studies used natural environmental conditions to assess the effect of heat stress in animals. Most of the studies were performed in the Americas and Asia, and three journals provided one-third of the publications. The systematic evidence synthesis presented herein outlines the trends of research performed to assess the effect of heat stress on livestock and allowed us to define future secondary studies to extend our knowledge about the negative impact of heat stress on the productivity of farm animals..
Heat stress effects on livestock: molecular, cellular and metabolic aspects, a review
Journal of Animal Physiology and Animal Nutrition, 2015
Elevated ambient temperatures affect animal production and welfare. Animal's reduced production performances during heat stress were traditionally thought to result from the decreased feed intake. However, it has recently been shown that heat stress disturbs the steady state concentrations of free radicals, resulting in both cellular and mitochondrial oxidative damage. Indeed, heat stress reorganizes the use of the body resources including fat, protein and energy. Heat stress reduces the metabolic rates and alters post-absorptive metabolism, regardless of the decreased feed intake. Consequently, growth, production, reproduction and health are not priorities any more in the metabolism of heat-stressed animals. The drastic effects of heat stress depend on its duration and severity. This review clearly describes about biochemical, cellular and metabolic changes that occur during thermal stress in farm animals.
The Impact of Heat Load on Cattle
Animals, 2019
Heat stress and cold stress have a negative influence on cattle welfare and productivity. There have been some studies investigating the influence of cold stress on cattle, however the emphasis within this review is the influence of heat stress on cattle. The impact of hot weather on cattle is of increasing importance due to the changing global environment. Heat stress is a worldwide phenomenon that is associated with reduced animal productivity and welfare, particularly during the summer months. Animal responses to their thermal environment are extremely varied, however, it is clear that the thermal environment influences the health, productivity, and welfare of cattle. Whilst knowledge continues to be developed, managing livestock to reduce the negative impact of hot climatic conditions remains somewhat challenging. This review provides an overview of the impact of heat stress on production and reproduction in bovines.
Physiological and Metabolic Adaptation of Livestock to Heat Stress 1
2017
India lying in the warm climatic zones of the world is subjected to extended periods of high ambient temperature and relative humidity. Despite of these high ambient temperatures, high direct and indirect solar radiation and humidity in tropical, sub-tropical and arid areas, native cattle sustain well by adapting to the environment through certain physiological and metabolic alterations in their body. These include alteration in water and electrolyte metabolism, changes in physiological parameters, exhibition of nycthermal pattern of acid-base balance, variations in secretion rate of various hormones and biochemical parameters. Hormones play a key role in thermal adaptation by involving with nutrient partitioning and homeorhesis or for homeostatic regulation, augmented by thermal stressor. All these adaptive physiologic responses are more pronounced in the native cattle Bos indicus than the exotic Bos taurus making them a thermotolerant breed.
Journal of Animal Behaviour and Biometeorology, 2017
This review aimed to detail the main information pertinent to the physiological and behavioral mechanisms evidenced in cattle under heat stress conditions. Brazilian cattle-breeding represents the second largest herd in the world, promoting great impact on the country's exports. Throughout their adaptability, these animals were submitted to different environments, which directly influence productive and reproductive performance, seeking compensatory mechanisms to maintain body homeostasis. Therefore, we can consider that heat stress directly affects the physiological and behavioral responses of cattle subjected to high temperatures. Adaptability of breeds to tropics should be considered of extreme importance in the choice of a productive activity for cattle-breeding and, particularly, in hot environments.
Review: Adaptation of animals to heat stress
Animal, 2018
Livestock plays an important role in the global economy. Climate change effects are not only limited to crop production, but also affect livestock production, for example reduced milk yields and milk quality, reduced meat production and reduced fertility. Therefore, livestock-based food security is threatened in many parts of the world. Furthermore, multiple stressors are a common phenomenon in many environments, and are likely to increase due to climate change. Among these stresses, heat stress appears to be the major factor which negatively influences livestock production. Hence, it is critical to identify agro-ecological zone-specific climate resilient thermo-tolerant animals to sustain livestock production. Livestock responds to the changing environments by altering their phenotypic and physiological characters. Therefore, survivability of the animal often depends on its ability to cope with or adapt to the existing conditions. So to sustain livestock production in an environmen...
Physiological and pyhsical responses of dairy cattle to heat stress
Black sea journal of agriculture, 2022
Herd management and nutrition strategies against increasing negative effects of global warming on farm animals have been the subject of significant debates in recent years. The fact that the changes in the environmental conditions are directly related to the habitats of the animals and the conditions inside the barn can affect the farm animals negatively. Although effects of heat stress differ according to species, especially high-yielding dairy cattle exposed to heat stress, respond with various interactive mechanism such as physiological, biochemical, immunological, anatomical and behavioral. Therefore, with the selection practices that have been going on for many years to improve the yield characteristics of the animals significantly increased. In this respect, the increased heat load in the body of dairy cattle due to the high productivity decreases their tolerance to environmental conditions. This situation adversely affects the productivity of cows with high breeding value. Yield losses, varying according to some factors about heat stress, can be partially explained by decreasing feed intake as a result of a series of hormonal responses affecting appetite center. However, the physiological requirements of cattle must be defined in order to develop appropriate strategies to reduce or eliminate the negative effects of heat stress. In this review, the variations in physiological, biochemical and behavioral mechanisms originating from heat stress in dairy cattle and the care, nutrition and herd management strategies that can be applied to eliminate or reduce the negative effects were discussed.