Bioscientifica Proceedings

Development of the corpus luteum (CL) in ruminants occurs in a rapid and time-dependent manner within 1 week after ovulation, with morphologic and biochemical changes in the cells of the theca interna and granulosa cells of the preovulatory follicle. These changes involve luteinisation of steroidogenic cells and angiogenesis to establish normal luteal function (progesterone secretion). The CL is composed of a large number of vascular endothelial cells, large and small steroido...

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 c...