Effect of heat stress on animal production and welfare: the case of dairy cow

Heat stress affects directly and indirectly metabolic and, physiological acclimation which may reduce the synthesis of milk and makes dairy cows more susceptible to illness. In the present review, after a brief description of heat stress effects on the dairy cow metabolism, nutritional, management and genetic strategies able to tackle heat stress effects were evaluated. As regard the nutrition strategies, die main rule to prevent negative effect of heat stress is to increase the energy and protein density of the diet and to maintain a high efficiency of the rumen activity. In order to mitigate the heat stress two management strategies may be applied: 1) cooling the barn and, in general, the environment of the herd; 2) cooling directly the animals. Finally, recent studies showed that in dairy cattle the heat tolerance genetic component was not negligible, suggesting that heat tolerance selection should be included in the selection objectives