In the current breeding practices, management of the estrous cycle is a common. Breeders want to know when their mare is in one phase or the other and also wants to be able to determine when she will ovulate. Manipulation of the estrous cycle is a practice of breeding management. Manipulation of estrous involves changing the normal cycle through hormone treatments or other methods. Managing and manipulating the estrous cycle allows breeders to have control over the phase the mare is experiencing and the length of time she will be in that phase.
Estrus synchronization is the practice of regulating when one or many mares will be in estrus. Breeders can follow certain protocol in order to cause synchronization in the cycle. According to Samper (2009), there are three methods of inducing estrus. These are induction of luteolysis, prevention of estrus using progestins and progesterone with estradiol which allow natural luteolysis to occur and are almost always combined with a treatment for ovulation induction, and follicular ablation. This paper with examine and explore the hormones, methods, doses and protocols used to synchronize estrus in the mare.
There are many reasons why breeders may want to synchronize the estrus cycle in a mare. When using cooled or frozen semen for an artificial insemination, synchronization of the estrus cycle can greatly increase the effectiveness of the breeding(s). There is a limited amount of time in which the mare is able to get pregnant, by synchronizing her estrus cycle, her chances of ovulating during that small window of time is greatly increased. Estrus synchronization allows breeders to coordinate several different mares’ ovulations in order to prepare them for embryo or oocyte transfer. Many mares may also have their estrus cycles synchronized so that multiple breedings can be done from a single shipment. If both the mare and the stallion are performance horses, they will have busy schedules to coordinate that may not at all correspond with the mare’s natural estrus cycle Estrus synchronization is used to better coordinate the mare’s cycle with the breeding schedule of the stallion. If the stallion only offers scheduled appointments, you may have to schedule in advance and not know when your mare will be in estrus that far ahead. In all cases, estrus synchronization minimizes the number of inseminations each mare will require per cycle in order to become pregnant.
A review of the estrous cycle is necessary to understanding the protocols for estrus synchronization. The estrous cycle of the mare is the period from one ovulation to a subsequent ovulation. Horses are a seasonally polyestrous animal meaning that non-pregnant mares experience recurring estrous cycles. Further, the equine breeding season is regulated by photoperiod, light exposure. The mares’ estrous cycle is 21 to 22 days in length and involves hormones produced by the pineal gland, hypothalamus, pituitary gland, ovaries and...