The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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YOUR GUIDE TO THE 2017 AAEP CONVENTION SPONSORED BY A31 TheHorse.com/AAEP2017 March 2018 THE HORSE AAEP Wrap-Up ALEXANDRA BECKSTETT; ERICA LARSON Stallion Collection Schedules Affect Mare Pregnancy Rates rtificial insemination can be an expensive, management-intensive endeavor for mare owners. They must time the mare's ovulation precisely with the availability of good-quality se- men. Therefore, owners are often at the mercy of when their desired stallion is collected and, if dealing with shipped se- men, when that semen arrives. Lisa Metcalf, MS, DVM, Dipl. ACT, owner of Honahlee PC, a breeding facility in Sherwood, Oregon, recently looked at how collection and insemination sched- ules affect pregnancy rates in mares bred using fresh or cooled semen. Breeding stallion collection sched- ules vary widely, said Metcalf. Many are collected every other day, while others are collected daily, weekly, Monday- Wednesday-Friday, or between horse shows. This poses a problem for mare owners working with a limited breeding window due to the short lifespan of the mare's oocyte and the stallion's sperm. In her study, Metcalf compared preg- nancy rates when stallions were avail- able for daily collection to rates from a prior study in which stallions were on an every-other-day schedule and analyzed the differences between on-farm (fresh) and shipped semen (cooled) insemination pregnancy rates. In the current study, she documented 417 mare cycles, inseminat- ing mares with fresh semen during 73 of the cycles and shipped semen during 344. All were bred with semen containing at least 500 million motile sperm (the gold standard) from one of four proven stal- lions 24 hours after induced ovulation. "There was a significant difference between on-farm (75%) versus shipped semen (63%) pregnancy rates," she said. "And pregnancy rate significantly increased for both on-farm and shipped semen inseminations when stallions were available daily." This confirms that the duration of time from collection to insemination signifi- cantly affects pregnancy rates, she said. Metcalf offered recommendations for breeders and their vets to maximize their chances of a successful pregnancy: ■ Know the stallion's contract terms (how frequently he is available, how many collections are permitted, etc.); ■ Communicate with mare owners and stallion managers; ■ Use same-day delivery for semen; ■ Find a reliable courier to transport semen; and ■ Set a standard for stallions to be avail- able every day during breeding season. Overcoming Three Embryo Transfer Obstacles Veterinarians routinely perform em- bryo transfers to obtain foals from valu- able mares that are unavailable to carry a pregnancy for a variety of reasons. They face three common challenges, however, when completing these procedures. Ryan Ferris, DVM, MS, Dipl. ACT, owner of Summit Equine, in Newberg, Oregon, described how to overcome them. While he was an assistant professor at Colorado State University's (CSU) Equine Reproduction Laboratory, in Fort Collins, Ferris and colleagues performed three studies during the 2016/17 breeding sea- son to address the following issues. 1. What media should veterinarians use for embryo recovery? "The options for embryo recovery fluid can be overwhelming," Ferris said, referring to what the vet uses to retrieve the embryo from the uterus. Clinicians at CSU typically use a complete flush media (a ready-to-use solution that doesn't require additions of serums or antibiot- ics), whereas in many other countries practitioners use Ringer's lactate solution or Hartmann's solution, which U.S. vet- erinarians also use during uterine lavage. During the 2016 breeding season Ferris and his team alternated using com- plete flush media (78 embryo recovery attempts) or Hartmann's solution (77 STEPHANIE CHURCH/THE HORSE Improving the Breeding Game