The horse undergoes an estrous cycle that lasts for 19-22 days. This timescale contains two phases: estrus phase- which is 5-7 days long and is when estrogen is secreted by the follicle and an oocyte begins ovulation. The second phase is known as the luteal phase which is 14-15 days in length- this is the stage in which the corpus luteum secretes progesterone. This is the same process as positive feed back in humans. These stages are in place for the development of an oocyte.
More hormones are involved in the estrous cycle, compared with the four hormones involved in human ovulation, as well as LH, FSH oestrogen and progesterone there is also the following hormones involved: GnRH, eCG. GnRH releases LH and FSH and eCG helps the development of foetal gonads.
Horses usually give birth during the summer period and prepare during the rest of the year. This is…