Heat stress management in dairy bovines: An overview

Abstract

With the consistent increase in milk consumption in the country, it is important to develop new technologies for higher milk production. However, the performance of dairy cows, including the yield and composition of milk, are depressed by heat stress. This paper reviews factors affecting the thermal balance as well as reproduction and production of lactating cows in hot environments. Thermal environments have several aspects, including air temperature, humidity, air movement, and radiation rate. However, the effective temperature is a simple and useful indicator for estimating the performance of lactating cows. Shade, fans, mist and fan systems, and night grazing and their effects, are presented as methods of modifying the environments of dairy cattle. Although heat stress causes a decline in dry matter intake, the cow's energy and protein requirements in hot environments increase. Therefore, it is important to increase the energy and by-pass protein contents of diets in order to maintain the performance of dairy cows in a hot environment.