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.

Heat stress poses major challenges to the dairy industry, disrupting the well-being and productivity of cows. Besides affecting lactating cows, exposure to heat stress during the dry period increases core body temperature (CBT) and alters hormonal profile and mammary gland development, ultimately affecting milk yield in the subsequent lactation. Reproductive performance is severely reduced in dairy cows exposed to heat stress. Even though it is well accepted that estrus expression is reduced during periods of heat stress, it is not clear whether herd-level indicators of estrus-detection efficiency, such as insemination risk, are impacted during periods of heat stress. This dissertation focused on exploring the use of CBT during the dry period as a predictor of postpartum health, production, and reproductive performance during the subsequent lactation. Furthermore, potential implications of heat stress and other seasonal stressors on insemination risk were evaluated. Study 1 investigated the relationships between CBT during the dry period and health, milk production, and reproduction during the subsequent lactation. Dry cows with increased CBT were more susceptible to health disorders and had reduced milk yield early in the subsequent lactation. No association was observed between CBT during the dry period and reproductive performance after parturition. Study 2 explored factors associated with CBT in dry dairy cows and focused on determining the ideal time of the day to assess CBT of heat-stressed dry cows. Core body temperature was increased in cows pregnant with twins and was associated negatively with gestation length. Furthermore, results indicated that 2215 h is the most appropriate time of the day to assess CBT of dry cows exposed to heat stress. Study 3 aimed to compare physiologic and metabolic characteristics of cooled cows classified as having high or low CBT during the dry period. In addition, this study investigated the association between CBT during the dry period and health, milk yield, and reproductive performance after parturition. Cows with high CBT during the dry period had distinct concentrations of pregnancy-associated glycoprotein and indicators of energy balance during the transition period and had reduced milk yield compared with low-CBT cows. Furthermore, CBT during the dry period was a useful predictor of postpartum health disorders. Reproductive performance, however, did not differ between cows that had high or low CBT during the dry period. Study 4 investigated temporal patterns of insemination risk in large dairy herds and explored associations between insemination risk and herd-level traits. Seasonal variation of insemination risk was minimal, with increased insemination risk observed during autumn. Greater values of insemination risk were observed in dry-lot herds, with low mortality of cows, and longer voluntary waiting period for primiparous cows. In summary, assessment of CBT in dry cows may be a useful tool to identify groups of cows more likely to present health disorders and impaired productive performance after parturition. In addition, insemination risk is not reduced during the summer, but it is severely affected by herd-level traits such as housing system, mortality of cows, and voluntary waiting period for primiparous cows.

Heat stress may negatively alter the barrier integrity of mammary epithelium, whereas organic source of dietary zinc has been shown to enhance epithelial integrity. The objective of the first study was to evaluate the effect of environmental heat stress and dietary zinc source (zinc-MET complex vs. zinc hydroxychloride) on lactating Holstein cows' performance and permeability of mammary epithelium. Heat stress impaired cow's performance and increased gene expression of tight junction proteins in mammary tissue. Replacing a portion of zinc hydroxychloride with zinc-MET complex had no impact on cow performance but improved mammary epithelial integrity. The objective of the second study was to examine the effect of repeated mammary tissue collections during lactation on cow performance and udder health of lactating dairy cows. Lactating cows recovered rapidly from mammary tissue collections and no long term impacts of repeated mammary biopsy procedures on DMI, milk yield and composition, or udder health were observed.

Michael Akers provides the basics for understanding mammary development and lactation and conveys the critical regulatory events in lactation. This text willl prove to be an invaluable overview of mamorary development and lactation for undergraduates and graduates studying lactation, new researchers, and as a review for established scientists. Additionally, the book will be an important resource for professionals in the animal and dairy industry and for those in other scientific disciplines such as food chemistry, cell biology, and endocrinology whose work is closely tied to mammary gland development and function. Lactation and the Mammary Gland covers growth and development of the mammary gland including comparisons between species. It imparts and emphasizes the critical nature of mammary growth and the onset of lactation at the time of parturition. Special emphasis is given to the endocrine and growth factor regulation of both mammogenesis and lactogenesis. A thorough discussion of the role of growth hormone in development and maintenance of lactation or galactopoiesis adds to this book's value as a text and reference. The author reviews the presence of hormones, growth factors, and other bioactive compounds in milk and mammary secretions as well as the potential for use of the mammary gland as a bioreactor in the pharmaceutical industry. A description of the nutritional and management factors in milk production round out the book's comprehensive coverage.

Ecological and bioclimatological aspects. Basic physiological mechanisms. Adaptation to specific environments. Species-specific adaptations. Techniques of investigations.

Two strategies to reduce impact of heat stress on high producing dairy cows were examined. The first was to recalculate the temperature-humidity index (THI) using high producing dairy cows under diurnal summer conditions. This re-evaluation confirmed that current THI values underestimate the severity of heat stress levels. Therefore, cooling of dairy cattle during warm summer months should begin at a THI of 68.A second objective involved three studies carried out to evaluate use of niacin in dairy cow rations to improve evaporative heat loss and resistance to heat stress. Niacin is known to cause intense vasodilation in human and lab species. We hypothesized that increasing vasodilation would improve evaporative heat loss in dairy cows. In the first niacin study, supplementation of lactating dairy cows with an encapsulated rumen by-pass form of niacin (NIASHURETM; Balchem Corporation, New Hampton, NY) and proved effective in alleviating some affects of heat stress during mild thermal stress. This was observed through increased evaporative heat loss, increased water intake to support the increased sweating rate, decreased rectal and core temperatures. Past research demonstrated that the possible mechanism for vasodilation affects seen by niacin were most likely due to prostaglandin D secretions. Niacin apparently may act through increased prostaglandin D and E production and secretion by Langerhans cells which then act upon vascular endothelial prostaglandin D receptors to increase vasodilation. Additionally, we and others have now shown that these prostaglandins induced elevated heat shock protein gene expression leading to improved cellular viability under heat stress conditions (42 ðC). No studies have evaluated impact of encapsulated niacin on milk yield and composition during periods of thermal stress under commercial dairy conditions. Therefore, the objective of the last study was to examine the effects of encapsulated niacin during heat stress on milk production and composition as well as core body temperatures under commercial conditions. We concluded that feeding encapsulated niacin did reduce body core temperature but did not increase daily milk yields; however, milk fat and protein percentages were increased thereby, increasing 4% fat- and energy-corrected milk yields significantly when animals were fed encapsulated niacin.