Resumo

GALVIS, Rubén D; MUNERA, Edwin A  e  MARIN, Andres M. Relations among the genetic merit to milk yield and metabolic and reproductive performance of high production cows. Rev Colom Cienc Pecua [online]. 2005, vol.18, n.3, pp.228-239. ISSN 0120-0690.

At the time that the genetic gain for milk production has increased, simultaneously, the cows’ reproductive performance has gotten worse; nevertheless, the physiological reasons of this antagonism are not well determined. Some researchers believe that the fertility drop is only a question of nutritional deficiency due to the longer demand that implies the greater productive level. The upgrading in milk production, increases the cows’ nutritional requirements; during the early postpartum period by natural reasons, a negative energy balance is showed and directly related with milk production, and according with some researchers has negative correlation with the first ovulation postpartum interval. Many health disorders in cows with intensive genetic selection, as metabolic as infectious source occurs in early lactation period, and are related to the low intake previous to calving. Genetic merit to milk yield could have a significant effect on the change pattern of metabolites and hormones plasmatic concentrations, which could had an effect on the postpartum ovarian activity. Although several researchers admit the lowest fertility is correlated with the highest milk production, they affirm that the milk production is not the limiting main factor of ovarian resumption, and the reproductive performance could be more influenced by the energy balance. The objective of this article is to review about the genetic progress to milk yield and its effects on the metabolic and reproduction performance of the high production cow.

Palavras-chave : energy balance; genetic improvement; metabolic profiles; ovarian resumption.

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