Biochemical and Physiological Changes during Thermal Stress in Bovines: A Review

The variation in climatic variables like temperature, humidity and radiations were recognized as the poten-tial hazards in the growth and production of all domestic livestock species. Thermal environment is a major factor that can negatively affect both production and reproduction in dairy animals, especially in animals of high genetic merit. Among the stressors, heat stress has been of major concern in reducing animal’s produc-tivity in tropical, sub-tropical and arid areas. There are few effective strategies for reducing the effects of heat stress on animal’s health and performance. The major strategiesproviding elaborate housinginvolving shade, sprinklers, fans, air conditioner, etc. are capital intensive, not very efficient and are of limited use for small and medium-size dairies. Sweating, high respiration rate, vasodilation with increased blood flow to skin surface, elevated rectal temperature, reduced metabolic rate, decreased DM intake, efficiency of feed utilization and altered water metabolism are the physiological responses that are associated with negative impacts of heat stress on production and reproduction in dairy animals.This article aimed to review bio-chemical and physiological changes which occur during thermal stress in bovines.