AAEP Convention 2005: Problems With Multiple Embryo Collection

Embryo transfer has been well-established in the horse industry as a method of obtaining multiple offspring from a valuable donor mare. The increased usage of this technique prompted Colorado State University (CSU) researchers to examine the effects of repeated embryo flushing. Elaine Carnevale, DVM, PhD, from CSU’s Animal Reproduction and Biotechnology Laboratory, presented the study’s findings at the 51st Annual American Association of Equine Practitioners Convention, in Seattle, Wash., Dec. 3-7, 2005.

"The advantages to obtain more than one foal during the breeding season is obvious for the owner, but what we are doing to the mare by multiple embryo transfers is insulting the mare’s uterus," Carnevale explained.

In the study, funded by the American Quarter Horse Association, the researchers found that repeated inseminations and embryo collections were associated with increased chronic uterine inflammation, but were not associated with increased infectious organisms within the uterus.

"During insemination, a significant insult occurs in the uterus," Carnevale reported. "If contamination is not overwhelming, the healthy uterus contends with the invasion through a series of events, resulting in an inflammatory reaction that helps to clear the uterus of sperm and contaminating debris."

Although not directly studied, other potential solutions offered by Carnevale included reducing the number of embryos collected per year, implementing rest cycles between collections, using superovulation (the production of multiple mature eggs in one cycle), and rotating embryo transfers with actual pregnancies. She added that antibiotics would probably not be beneficial, because the problems researchers noted were associated more with inflammation rather than infection.

Carnevale added, "Additional research is required to determine the long-term effects of chronic inflammation on uterine function and fertility."

About the Author

Chad Mendell

Chad Mendell is the former Managing Editor for TheHorse.com .

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