Bioscientifica Proceedings

Summary. The increase of milk yield in dairy cows during the last decades has been accompanied by a reduction in fertility. This decline in reproductive performance is most likely caused by the pronounced negative energy balance typically observed in high yielding dairy cows and in cows suffering from production diseases. Often, both phenomena occur coincidentally. Cows with a profound negative energy balance and production diseases show hormonal alterations compared to healthy cows which impair follicular development and oestrous behaviour, delayed resumption of ovarian cyclicity, increased risk of a persistent corpus luteum and decreased peripheral progesterone concentrations, with negative impacts on oocyte quality and embryonic development. However, until now it has not been proven that inflammatory diseases induce embryonic mortality. There is, on the other hand, strong evidence that a negative energy balance causes disturbances in uterine involution by an impairment of immune defense mechanisms. The underlying pathophysiological mechanisms are not yet completely clarified. It has been demonstrated, however, that an early ovulation after parturition delays the process of uterine involution. Taken together, both metabolic disorders as well as inflammatory processes have diverse negative effects on reproductive function and are some of the reasons for the decline of fertility in high yielding dairy cows.

© 2014 Society for Reproduction and Fertility