Efectos del estrés calórico en bovinos de leche y su influencia productiva

Abstract

Heat stress symbolizes one of the major factors in the environment that negatively affects the productive performance of cattle. Heat stress has a very significant effect on all livestock species causing too much economic losses and also much concern regarding animal welfare. Stress affects both the quantity and quality of milk produced, in addition to having negative effects on production and reproduction of dairy cattle, being more aggressive on animals with high productive potential. Environmental conditions, mainly high temperature and relative humidity in dairy cows, have a negative impact on their production and behavior. Heat stress is produced by the increase in environmental temperature, which causes the animal to lose the biological balance between metabolic heat generation and its dissipation to the environment or thermoregulation. The decrease in milk production in animals under different heat stress situations is due to the fact that feed intake decreases, while the animal's energy needs increase. In addition, heat stress reduces milk fat and protein concentration, inhibits rumination behavior and produces immunosuppression, thus increasing the incidence of some diseases. Finally, heat stress drastically reduces reproductive indices, since it decreases the synthesis and release of LH and GnRH hormones, inhibits ovulation and the expression of estrous behavior.