Em­bryo Trans­fer Ex­pands Po­ten­tial

Practical Horseman - - BORN TO PERFORM -

To date, Wei­he­gold has pro­duced at least 12 foals via em­bryo trans­fer/ sur­ro­gacy and her ba­bies are by such su­per­star stal­lions as Jazz, Toti­las and Sir Don­ner­hall I.

As founder and owner of Palm Beach Equine Clinic, Dr. Scott Sw­erdlin over­sees em­bryo trans­fers for mul­ti­ple per­for­mance mares each year. His team of 26 vet­eri­nar­i­ans in­cludes spe­cial­ists in surgery, in­ter­nal medicine, ra­di­ol­ogy, re­pro­duc­tion and fer­til­ity.

Ac­cord­ing to Dr. Sw­erdlin, “Em­bryo trans­fer is non-in­va­sive and very safe.” He says the “trick­i­est part” of the pro­ce­dure is getting the mare im­preg­nated, so Dr. Sw­erdlin of­ten brings mares to the clinic for a few days for in­sem­i­na­tion, which al­lows them to have an ul­tra­sound ev­ery two hours. Frozen se­men can then be de­posited when and how the mare is most likely to take. Seven to eight days later, the em­bryo is flushed from the donor mare’s uterus and trans­ferred to the re­cip­i­ent mare. The em­bryo col­lec­tion it­self is a pro­ce­dure so sim­ple it can take place in a field at the mare’s home sta­ble. At Dr. Sw­erdlin’s home-base in Florida, where the weather is warm year-round, a mare may have 10 heat cy­cles per year and one could po­ten­tially fur­nish an em­bryo at each cy­cle.

The im­pli­ca­tion of this pro­ce­dure for sporthorse breed­ing is im­mense. It im­plies that high-level sport mares like Wei­he­gold can con­tinue to com­pete while si­mul­ta­ne­ously hav­ing a pro­lific in­flu­ence as a brood­mare. Ac­cord­ing to Dr. Sw­erdlin, “It’s of­ten some­where around 11 or 12 years of age that you’ll know you have a re­ally top mare—she’s hit­ting her per­for­mance peak. That’s the time to col­lect. If you’re not ready for the foal for what­ever rea­son, you can freeze the em­bryo. A mare’s re­pro­duc­tion po­ten­tial starts to de­cline at age 13 or 14, so these years can be so im­por­tant in terms of col­lec­tion. For­merly, we’d have about a 30 per­cent suc­cess rate with frozen em­bryos, but with the new pro­ce­dure that we’re us­ing [cell wall col­lapse] and spe­cially trained tech­ni­cians, we’re getting a 70 per­cent suc­cess rate.”

An im­por­tant im­pli­ca­tion of the pro­ce­dure is that top-per­form­ing mares can now be bred more fre­quently to di­verse top-per­form­ing stal­lions to see which pair­ing yields the most im­pres­sive foal crops. For ex­am­ple, con­sider that 13-year-old Wei­he­gold is still ac­tively per­form­ing at the FEI level, but in past gen­er­a­tions, she may not yet have had one foal and breed­ers cer­tainly would not have had the op­por­tu­nity to test her match with mul­ti­ple in­flu­en­tial stal­lions. There­fore, a mare’s prog­eny record to­day could con­ceiv­ably be 10 times as great as it would have been if she’d car­ried the foals her­self. Her in­flu­ence on the breed may also be greater, as there’s more room to play with spe­cific crosses and her per­for­mance record can be so­lid­i­fied over a life­time, as op­posed to last­ing just a few years.

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