Resumo

GONGORA, Agustín  e  HERNANDEZ, Aureliano. HIGH ENVIRONMENTAL TEMPERATURES AFFECT REPRODUCTION IN THE COW. rev.udcaactual.divulg.cient. [online]. 2010, vol.13, n.2, pp.163-173. ISSN 0123-4226.

A critical review regarding the reproduction physiology of the cow, related to the main effects of high environmental temperatures, in order to point out the scientific and economic importance of its adaptation to tropical conditions, in contrast to those prevailing in temperate zones, is presented. Follicular development, estrus, embryonic implantation, gestation, parturition and return to estrus within the postpartum period are affected. However, economic losses due to heat stress have not been estimated for the Colombian cattle industry and the same appears to be true for other tropical countries. Bos taurus derived genotypes seem to be more susceptible to heat stress than the Bos indicus, given their higher metabolic rate and lesser capacity for heat dissipation. Nevertheless, alterations due to heat stress should depend on the degree of adaptation of individuals or genotypes. For instance, in Colombia there are some B. taurus derived breeds which are adapted to temperature ranges, deleterious to non adapted breeds. It is recommended to establish protected zones for cattle to avoid direct sun radiation exposure and protection from low temperatures, in order to avoid the correspondent effects of temperatures, above or below the range which does not affect animal physiology. It is necessary to reorient the systems of genetic selection in order to select bovines which can adapt better to different climatic conditions existing within the tropics. It should be noted that high environmental temperatures depress food consumption which then interferes in the reproductive efficiency.

Palavras-chave : Heat stress; tropics; bovines; climate; estrus.

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