Optimal breeding conditions

For goats and sheep, management and nutrition as well as breeding technique play major roles in the success of a farm’s breeding program.

The University of Minnesota Extension and the North Dakota State University Extension partnered to present a webinar entitled, “Managing for Reproductive Success in Sheep and Goats” June 16. NDSU livestock extension specialists Lacey Quail, Ph.D., and Rachel Gibbs, Ph.D., spoke about managing for reproductive success in sheep and goats.

“It’s important to recognize that nutrition during the pre-breeding phase really drives ovulation rates and conception rates,” Gibbs said. “Whereas, when we move into early gestation, we are more focused on that nutrition driving embryo survival.”

For ewes and does, throughout pre-breeding and gestation, nutrition can affect ovulation, conception rate, embryo survival, placental growth and fetal growth, leading to lamb survival, Gibbs said. For rams and bucks, nutrition can affect semen quality, libido and breeding activity.

Gibbs recommends ensuring breeding animals are getting the correct amount of nutrients at least 60 days prior to breeding for both males and females. Farmers should check rams and bucks 60 days prior to breeding because the sperm production cycle is about 48-55 days, Gibbs said.

Increasing energy by 10% and protein by 18%, keeping less than 16% crude protein, will allow sires to reach a body condition score of 3-3.5, Gibbs said. This can also increase sperm production and semen quality in rams and bucks. Body condition score has a range of one to five — one being underweight and five being overweight — for goats and sheep.

“When we think about incorporating these ideas and making sure we’re in optimal breeding conditions, we really need to start evaluating our body condition scores,” Gibbs said. “(Doing this) about 60 days before the breeding season allows us time to make changes, nutritional adjustments and to get them into an ideal body condition.”

Farmers can also do a nutritional flush on ewes and does about 14-28 days prior to breeding. This technique raises the intake of energy and overall nutrition and has been known to improve conception rates by about 25%. However, it is less effective for ewes and does in a body condition score of 3 or above, Gibbs said.

Typically nutritional flushing includes a 50%-100% increase in nutritional requirements, Gibbs said. With that, it is hoped that the animal’s body condition score improves to a 2.5-3.

“Nutrients get devoted to several other aspects of production before reproduction,” Quail said. “That’s why it is so critical to have your nutrition and your management of nutrition dialed in so that we can be successful reproductively.”

Aside from nutrition, many hormones play a role in the animal’s reproductive cycle — estrogen, luteinizing hormone, progesterone and prostaglandin. The average cycle for a sheep is 17 days, while the average cycle for goats is about 21 days.

“A hormone is going to initiate its behavior or initiate its role in an animal by reacting with its own receptor,” Quail said. “That’s a very unique, specific relationship between a hormone and its receptor.”

Estrogen, or estradiol, is responsible for the ewe or doe being receptive to breeding. This hormone peaks at the beginning and end of the cycle. Luteinizing hormone is responsible for releasing eggs and peaks around the same time as estrogen. The corpus luteum produces progesterone, which inhibits eggs from being released. Progesterone peaks in the middle of the cycle. Prostaglandin kills and inactivates the corpus luteum, so prostaglandin is increasing while progesterone is decreasing.

“This is definitely set up like a row of dominoes; you knock over one and a bunch more knock over,” Quail said.

During the cycle, a follicle on the ovary will rupture and release an egg. The follicle will then turn into a corpus luteum for the remainder of the cycle.

Sheep and goat farmers can choose to naturally or artificially inseminate their flock. If A.I. is used, there are three main ways of accomplishing it in sheep and goats — transvaginal, transcervical and laparoscopic.

Transvaginal is primarily used in goats and is otherwise known as splashing. This method, Gibbs said, should use fresh semen. Transcervical is the method most similar to A.I. methods done on cattle and is primarily used in goats and some sheep. Transcervical can use fresh or frozen semen. The final method is laparoscopic, Gibbs said, and is deemed the “gold standard” in sheep because it bypasses the cervix and deposits semen into the uterine horn. This method can also use fresh or frozen semen.

If a farm chooses to A.I. goats or sheep, there are various benefits, Gibbs said. It can increase the number of bred females per ejaculate, it can shorten the breeding season and lambing seasons, reduce the number of sires on-site, and enhance biosecurity and risk management on-site.

“When we think about capitalizing on superior genetics, oftentimes, we think about incorporating other sires outside of our own operation,” Gibbs said. “We can do that in a more bio-secure way if we incorporate fresh and frozen semen through artificial insemination.”

Although Gibbs talked about the benefits of A.I., she also mentioned some considerations. There is an upfront investment cost and a variable success rate with A.I. It also requires precise pre-breeding management and technical experience.

Quail touched on key points for the use of synchronization when inseminating sheep or goats: work with a veterinarian, know the desired goal, each hormone product has a different job, know how to store and use correctly, timing is important, and be sure to plan ahead.