The metabolic challenge of milk production and the toll it takes on fertility
Por:
Gutierrez C.G., Aguilera I., Leon H., Rodríguez A., Hernández-Cerón J.
Publicada:
1 ene 2005
Resumen:
Genetic selection for higher predicted breeding value (PBV) for milk production has altered the endocrine responses of the cow to the metabolic demands of lactation at the time that fertility has declined. The highly selected cow responds by mobilising body energy reserves more readily leaving itself more susceptible to energy deficits. When cows of high and low PBV were compared, ovulation occurred later in cows of higher genetic value. There were no differences in milk yield during the first 35 days of lactation, nor were there changes in body condition or weight loss. Nonetheless, cows with high genetic value had higher concentrations of GH and lower concentrations of glucose, insulin and IGF-I. Fatty acids mobilised during the early postpartum period are used by the liver and when they exceed the oxidative capacity of the liver, they accumulate causing fatty liver. We have found that indicators of hepatic tissue damage (AST and bilirrubin) and hepatic synthesis (cholesterol, triglycerides and protein) during the first two weeks postpartum are together more important for predicting the commencement of ovarian activity postpartum than indicators of tissue mobilisation (free fatty acids and urea) or energy status (glucose and insulin). Finally, targeted treatment of bovine somatotrophin (bST) at the time of artificial insemination increased conception rate in repeat breeders by around 10%. In superovulated cows bST increased the proportion of transferable embryos. Thus, management of the early postpartum period to minimise hepatic damage and targeted treatment for infertility with bST could improve fertility.
Filiaciones:
Gutierrez C.G.:
Departamento de Reproducción, Fac. de Med. Veterinaria Y Zootecnia, Univ. Nac. Auton. de Mex., México D.F., 04510, Mexico
Aguilera I.:
Departamento de Reproducción, Fac. de Med. Veterinaria Y Zootecnia, Univ. Nac. Auton. de Mex., México D.F., 04510, Mexico
Leon H.:
Departamento de Reproducción, Fac. de Med. Veterinaria Y Zootecnia, Univ. Nac. Auton. de Mex., México D.F., 04510, Mexico
Rodríguez A.:
Departamento de Reproducción, Fac. de Med. Veterinaria Y Zootecnia, Univ. Nac. Auton. de Mex., México D.F., 04510, Mexico
Hernández-Cerón J.:
Departamento de Reproducción, Fac. de Med. Veterinaria Y Zootecnia, Univ. Nac. Auton. de Mex., México D.F., 04510, Mexico
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