Donor and Recipient Management to Optimize Embryo Technology Success
By Troy Smith, field editor
DES MOINES, Iowa (Sept. 8, 2016) — “Embryo transfer sometimes seems to rely on witchcraft,” joked bovine reproduction specialist Cliff Lamb, explaining that too many of its practitioners seem to be constantly tinkering with their procedure. They’re always seeking some new “trick” that will improve success rates. Too often, the program changes have little or no basis in science.
“Be careful about looking for a silver bullet,” the University of Florida professor and researcher warned an audience gathered for the Applied Reproductive Strategies in Beef Cattle Symposium, hosted Sept. 7-8 in Des Moines, Iowa. “Consistency,” he added, “really is the key to success with embryo transfer.”
According the Lamb, the factors responsible for the success or failure with embryo transfer include nutrition, estrous-cycle control, and management of donor and recipient females. Lamb called donor and recipient management critical, since donors are expected to produce good-quality embryos and the recipients must be able to conceive to the transferred embryo, maintain the pregnancy until full term, calve without assistance, and raise a calf of high genetic merit.
While important to both donors and recipients, Lamb counts nutrition as the single greatest factor influencing donor cow response to superstimulation. Accordingly, it is important that donors be maintained on a positive plane of nutrition. However, Lamb does not advocate for popular dogma calling supplementation of donor cow diets with mineral from only organic sources. He discounted the notion that feeding organic mineral during the period prior to superovulation will enhance both the quality and number of embryos.
“As long as the animal’s mineral requirements are met, the mineral’s source (organic vs inorganic) probably makes minimal difference,” stated Lamb.
While discussing management of cows that are to be recipients of embryo transfer, Lamb said a useful method of increasing the number of animals receiving embryos is to utilize protocols that allow for embryo transfer without the need for estrus detection.
“I refer you to the (Beef Reproduction Task Force-recommended) protocol sheets for fixed-time AI (artificial insemination). They should work,” said Lamb. “However, the single most utilized protocol in the U.S. is the 7-day CO-synch system.”
Lamb also commented on the practice of administering human chorionic gonadotropin (hCG) at the time of embryo transfer. Citing related studies, he said use of hCG has been shown to increase pregnancy rates by about 6%. Lamb warned, however, that enhancement of pregnancy rates does not occur in every case. Generally, nutritionally compromised, thin cows appear to benefit, while well-conditioned cows do not.
Reiterating the influence of nutritional status, this time for recipient females, Lamb emphasized the importance of having recipients on an increasing plane of nutrition.
“It’s not all about BCS (body condition score) on the day of transfer,” explained Lamb. “I’d rather have a recipient at BCS 4 and increasing than have her at BCS 5, fallen from 6 and declining.”
Lamb spoke during Thursday’s ARSBC morning session. Visit the Newsroom at www.appliedreprostrategies.com, which features comprehensive coverage of the symposium, to view his PowerPoint, read the proceedings or listen to the presentation. Compiled by the Angus Media editorial team, the site is made possible through sponsorship by the Beef Reproduction Task Force.
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