Heat Stress in Dairy Cows - Reproductive Problems and Control Measures -

Abstract

All animals have a range of ambient environmental temperatures termed as thermo-neutral zone. This is the range of temperatures that are conducive to health and performance. The upper critical temperature is the point at which heat stress begins to affect the animal adversely. There are a number of environmental factors like high temperature, high humidity and radiant energy (sunlight) that contribute to heat stress. Heat stress has long been recognized as reducing both the productivity and reproductive efficiency of dairy cattle. Although heat stress has a direct effect on reproduction, it depends on the magnitude and duration of thermal stress, milk yield, lactation status, breed, composition of diet, dry mater intake and physical activity of animals. Further studies are needed to better understand the associations between climatic conditions and reproductive physiology and to evaluate the efficacy of various nutritional, environmental and reproductive strategies in a particular region for combating heat stress.