High milk production and good fertility in modern dairy cows: the results of some recent research items
2006
Opsomer, G, Ghent University (Belgium) | Leroy, J | Vanholder, T. | Bossaert, P. | Kruif, A.
The present manuscript summarizes the research, which is currently going on in our department regarding the interaction between negative energy balance (NEB) and fertility in modern high yielding dairy cows. In this work, it has been clearly demonstrated that nearly 50% of the recently calved dairy cows suffer from one or another ovarian dysfunction during the preservice postpartum period. Both clinical signs of a significant negative energy balance as well as the occurrence of puerperal disorders were main risk factors to suffer from these ovarian problems. In the following research using repeated ovum pick sessions it was demonstrated that homeorhetic changes of metabolites known as typical indicators of the negative energy balance, were reflected in the follicular fluid of the dominant follicle during the immediate postpartum period. Based on in vitro experiments it was furthermore shown that these metabolites were able to affect bovine granulosa cells at concentrations, which were found in the in vivo study. The latter opens perspectives in elucidating the question why high yielding dairy cows express less heat symptoms and why modern dairy cows are at an increased risk to suffer from postpartal ovarian dysfunctions such as cystic ovarian disease. Besides the effect on granulosa cells, studies were also carried out to investigate the effect of elevated levels of non esterified fatty acids (NEFAs) on the reproductive competence of the oocyte. In these studies it was demonstrated that NEFAs at levels, which could be found in vivo within the follicular fluid of the dominant follicle during NEB, may influence fertility of high yielding dairy cows by hampering the oocyte maturation as expressed in lower fertilization rates and subsequently lower cleavage and blastocyst development. The latter opens possibilities to explain the worldwide mentioned decreasing fertility results seen in modern high yielding dairy cows
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