Synchronizing Estrus

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There are many reasons goat breeders might decide to use either group breeding or artificial insemination (A.I.). While both these breeding methods are quite simple, there are plenty of details that can impact success — one of the most notable is the doe’s stage in heat. As a remedy to this, many breeders using A.I. (and natural service in group and hand breeding) choose to use some form of estrus synchronization. 

Estrus synchronization is simply any method used to bring an individual or group of animals into an optimal physiological state for ovulation and, thereby, conception. Besides reducing some breeding season headaches, this is also especially helpful to develop a specific kidding window.  

Many forms of synchronization are designed to bring does into a standing heat within 48 hours. While this greatly reduces the burden of heat checks and tracking natural cycles, it still requires strict attention, observation, and good methodology. 

Synchronization methods 

The nature and function of the doe’s estrous cycle system are easy to manipulate, especially during the typical late-year breeding season. Various synchronization protocols and products are available. Choosing the “right one” depends on the flexibility of the breeder and personal preference. Fellow goat breeders may have their recommendations and methods they swear by; they are certainly worth the listen but don’t be afraid to experiment a bit to find what works best for your herd. 

Overall, it is believed that for goats, progesterone-based (a hormone secreted from the corpus luteum, or CL, on the ovary that sustains pregnancy after conception) protocols tend to be more successful than prostaglandin-based (a hormone secreted by the uterus used in the luteolytic, or degradation, process of the CL each cycle) injection protocols. 

Note: Synchronization protocols use “days” to track the 21-day cycle and synchronization process timeline. 

Progesterone-based synchronization protocols involve placing a sponge soaked in the hormone or controlled internal drug release (CIDR) device into the doe’s vagina for a while. Essentially, the presence of this hormone makes the doe’s body think she is pregnant. When removed, usually seven to nine days later, the doe is given an injection of prostaglandin and comes into heat approximately 48 to 96 hours later. (Different products used may have different timing results, but they are usually within the timeframe.) 

This is a basic outline of the procedure, but multiple injections with different prostaglandin products may be used depending on what protocol you are following. Does can also be bred using a CIDR or sponge without a prostaglandin shot, usually coming into heat 36 to 72 hours later. If the doe returns to heat one to two weeks later, she should be rebred.  

Note that heat checking will need to be done routinely after the device is removed, no matter what protocol is used. The signs to watch for are the usual indicators of natural heat, including flagging, restlessness, vocalization, and, most importantly, the presence of mucus. Sometimes the hormone GnRH (using a product such as Cystorelin®) is also given when the CIDR or sponge is put in. Research has suggested this step may have some additional effectiveness.  

Another method of heat induction is using Lutalyse®, a prostaglandin product. When the first shot is given, the doe’s cycle is at “Day 0” because any presence of a CL is destroyed. On day 10 another shot is given, and the doe will come into heat up to seven days later. When using this method, breeders are encouraged to use the “AM-PM rule,” which means if the doe shows signs of heat in the morning, she should be serviced that evening and vice versa to breed closest to the time of ovulation.  

The University of North Caroline came up with a similar protocol involving Lutalyse and Cystorelin®, where the final dose is administered and the doe serviced on Day 17 of the program. 

Large dairies who wish to continually cycle animals to induce estrous out of season can use artificial lighting to raise melatonin levels to naturally cause does to resume heat cycling — even in summer months. This isn’t common a common practice, but protocols and information are available. 

Considerations 

While there are multiple progesterone and prostaglandin products on the market effective in goats, they are almost always an “off label” usage as official guidelines for use in goats have not yet been established. Before using any of these products, be sure to get a veterinarian’s approval and recommendation.  

Using synchronization certainly saves a lot of sanity in breeding, especially when multiple animals are involved. It can be intimidating to try at first, but with a bit of education on heat cycles and an established protocol, many breeders have found it well worthwhile.  

The importance of manual heat checks cannot be understated, even when these protocols are used. Be sure to learn all the symptoms of standing heat and learn what behavior looks like for your specific animals. 

Bibliography 

Goats. (2019, August 14). Estrus Synchronization for Timed Artificial Insemination in Goats. Goats. https://goats.extension.org/estrus-synchronization-for-timed-artificial-insemination-in-goats/.  

Goats. (2019, August 14). Goat Reproduction Estrous Synchronization. Goats. https://goats.extension.org/goat-reproduction-estrous-synchronization/.  

Omontese, B. O. (2018, June 20). Estrus Synchronization and Artificial Insemination in Goats. IntechOpen. https://www.intechopen.com/books/goat-science/estrus-synchronization-and-artificial-insemination-in-goats.  

Originally published in the September/October 2021 issue of Goat Journal and regularly vetted for accuracy.