Heat Stress and Animal Productivity

Heat stress occurs when there is an imbalance between heat production within the body and its dissipation. This book examines heat stress and animal productivity, and offers solutions for combating the effects of climate-induced temperature rise on animals.

Dr. Anjali Aggarwal is working as a Senior Scientist at National Dairy Research Institute, Karnal (India). She holds a PhD degree in Animal Physiology and is involved in research and teaching at post-graduate level. Her area of research work is stress and environmental physiology. She has more than 50 publications, two technical bulletins, four manuals and many book chapters to her credit. She has successfully guided many post-graduate and PhD students. Her major research accomplishments are on microclimatic modification for alleviation of heat and cold stress, mist and fan cooling systems for cows and buffaloes, and use of wallowing tank in buffaloes. Her work involves the use of technology of supplementing micronutrients during dry period and early lactation to crossbred and indigenous cows for alleviating metabolic and oxidative stress and improved health and productivity. Studies are also done in her lab on partitioning of heat loss from skin and pulmonary system of cattle and buffaloes as a result of exercise or exposure to heat stress. Dr. R.C. Upadhyay is working as Head, Dairy Cattle Physiology Division at National Dairy Research Institute, Karnal (India). He graduated in Veterinary Sciences and obtained his PhD degree in Animal Physiology. His area of recent research is climate change, stress, and environmental physiology. His major research accomplishment is on climate change impact assessment of milk production and growth in livestock. His work also involves studying methane conversion and emission factors for Indian livestock and use of IPCC methodology of methane inventory of Indian livestock. Heat shock protein-70 expression studies in cattle and buffaloes are also done in his lab. Draught animal power evaluation, fatigue assessment, work-rest cycle and work limiting factors form the highlights of his work. Studies on partitioning of heat loss from skin and pulmonary system of cattle and buffaloes and electrocardiographic studies in cattle, buffalo, sheep and goat are also undertaken in his lab. He has more than 75 research papers, four books and several book chapters to his credit. Technologies developed and research done by him include methodology of methane measurement: open and closed circuit for cattle and buffaloes; inventory of methane emission from livestock using IPCC methodology; livestock stress index: thermal stress measurement based on physiological functions; and draught power evaluation system and large animal treadmill system. He received training in Radio-nuclides in medicine at Australian School of Nuclear Technology, Lucas heights, NSW, Australia in 1985 and Use of radioisotopes in cardiovascular investigations at CSIRO, Prospect, NSW, Australia, during 1985-86. He has guided several post-graduate and PhD students. He is recipient of Hari Om Ashram Award-1990 (ICAR) for outstanding research in animal sciences.

CHAPTER 1 Thermoregulation.- 1. Introduction.-2. Thermoneutral zone.- 3. Heat stress indicators.- 4. Adaptation to high temperature.- 5. Thermoregulatory mechanisms.- 6. Response to heat stress.- 6.1Water vaporization.- 6.2 Physical responses.- 6.3 Sweating and panting.- 7.Heat production.- 8. Heat Increment.- 9. Assessment of Adaptability.- 10.Genetic adaptations/cellular changes during heat stress.- 11.Genetic improvement for adaptation.- 12. Genomic responses during acclimation.- CHAPTER 2 Heat stress and Hormones.- 1.Introduction.- 2.Thyroxine (T4) and triiodothyronine (T3).- 3.Cortisol.- 4. Insulin.- 5. Insulin like growth hormone 1 (IGF-I).- 6.Growth hormone.- 7.Aldosterone.- 8.Adiponectin and leptin.- 9.Reproductive hormones.- 10.Catecholamines.- 11.Prolactin.- CHAPTER 3 Heat Stress and Milk Production.- 1.Introduction.- 2.Effect of climatic variables on milk yield.- 3. Behavior of cows during heat stress.-4.Effect of heat stress on bovine somatotropin (bST) administered cows.- 5.Metabolic heat production.- 6.Role of Acclimation during heat stress.- 7.Metabolic Adaptations to Heat Stress.- 8.Mechanism by which heat stress reduces milk production.- 9.Mechanism of regulation of milk secretion and mammary function.- 10. Heat Stress Effects on Heifers.-11.Genetic factors regulating response to heat stress.- 12.Reducing Heat Stress in dairy animals.- 13.Effect of heat stress on milk production in Buffaloes.- CHAPTER 4 Heat stress and Reproduction.- 1. Introduction.- 2. The effect of heat stress on reproductive functions.- 3. The effect of heat stress on the hypothalamic hypophyseal ovarian axis.- 4.Female reproduction.- 4.1 Ovarian follicle.- 4.2 Steroid production.- 4.3 The oocyte.- 4.4 Embryonic development.- 4.5 Fetal development.- 4.6 Uterine environment.- 5.Male reproduction.- 6.Effect of heat stress on reproduction by altering energy balance.- 7. Genetic plasticity controlling the magnitude of heat stress effects.-8.Consequences of action of climate change on reproduction for species survival and distribution.- 9.Reproduction in buffaloes .- 10.Management and production systems that can improve fertility during summer months.- CHAPTER 5 Heat stress and immune function.- 1 Introduction.- 2 Innate and adaptive immunity.- 3 Heat stress and Cell-mediated immunity.- 4 Regulation of stress response.- 4.1 Role of glucocorticoids and catecholamines.- 4.2 Role of cytokines.- 4.3 Role of stress hormones.- 5 Acute and Chronic Stressors .- 6 Mechanism of action of heat stress on immunity .- 7 Nutrition and immunity.- 7.1 Vitamins.- 7.2 minerals.- 8 Effect of free radical production on immunity and role of antioxidants.- CHAPTER 6 Biological Rhythms.- 1. Introduction.- 2. Circadian timekeeping mechanisms.- 2.1 Biological clock.- 3. Daily rhythms.- 4. Annual rhythms.- 5. Functions of sleep.- 6. Pineal gland and melatonin.- 6.1 Synthesis and metabolism of melatonin.- 6.2 Melatonin receptors.- 6.3 Daily rhythm of melatonin .- 6.4 Annual rhythm of melatonin.- 7. Cortisol.- 7.1 Daily rhythm of cortisol.- 7.2 Annual rhythm of cortisol.- 8. Leptin.- 8.1 Daily rhythm of leptin.- 8.2 Annual rhythm of leptin.- 9. Lipid metabolism.- 9.1Lipid metabolism in ruminants.- 9.2 Daily rhythms of free fatty acids (FFA) and glycerol.- 9.3 Seasonal variation of lipid metabolism.- 10. Feeding entrained circadian rhythms.- 11. Circadian clocks as mediators of the homeorhetic response to lactation.- 12. Oxidative stress.- 13.Circadian rhythm of cardiovascular parameters.- CHAPTER 7 Shelter Management for Alleviation of Heat Stress in Cows and Buffaloes.- 1. Introduction.- 2. Heat transfer and concentration and emission of harmful gases in dairy buildings.- 3. Cooling methods for alleviation of heat stress.- 3.1 Provision of shade.- 3.2 Ceiling fans.- 3.3 Evaporative cooling.