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Angus Journal
Copyright © 2015
Angus Journal

Managing Embryo Transfer
to Improve Success

Embryologists surveyed offer their opinions on ET protocols and factors affecting success.

SIOUX FALLS, S.D. (Dec. 4, 2012) — Areas of management where increased diligence can improve success of embryo transfer (ET) was the topic addressed by University of Florida reproductive physiologist Cliff Lamb during the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium Dec. 3-4 in Sioux Falls, S.D. Lamb cited results of a survey of embryologists to which respondents ranked factors believed to have significant impact on ET.

Cliff Lamb “Systems offering the best opportunities for AI also work for ET,” offered Cliff Lamb, who recommended the same protocols for fixed-time ET as for fixed-time AI.

“Embryologists were asked if they used fixed-time protocols for ET,” noted Lamb. “I thought it interesting that over 72% said ‘yes.’”

Lamb said he concurred, believing fixed-time protocols remove much of the error of heat detection and, for the most part, result in more pregnancies per 100 embryos transferred. He recommended the same protocols for fixed-time ET as for fixed-time artificial insemination (AI).

“Systems offering the best opportunities for AI also work for ET,” offered Lamb.

According to surveyed embryologists, the top three factors affecting fertility were embryo quality, ET technician skill and body condition score of recipient females.

“There’s no question that perception is correct,” agreed Lamb. “Embryo quality makes a big difference. The technician also is tremendously important.”

Lamb said recipient body condition is important, too, calling attention to its dynamic. The ongoing change of nutritional status matters, and it’s best if females are on an increasing plane of nutrition.

“We generally say it’s best if females have a body condition score (BCS) of 5 or higher,” added Lamb. “But I’d rather have a 4 moving toward 5 than a 6 going the other way.”

Click here to view larger image of Fig. 1: Embryologists’ rating
of relative impact on fertility of recipients to embryo transfer,
where 1 is least impact and 5 is greatest impact.

Lamb said other factors that influence ET success include embryo placement, with close proximity to the ovary being favored. With regard to fresh vs. frozen embryos, he said pregnancy rates with frozen embryos tend to be about 10% lower.

Lamb said he fields many questions regarding the importance of mineral supplementation and specifically whether organic sources are best.

“Having a balanced mineral program is more important than whether the product is organic or inorganic,” stated Lamb.

Lamb spoke during Tuesday's ARSBC session focused on advancing technology. Visit the Newsroom at to listen to his prentation and to view the accompanying PowerPoint and proceedings paper.

Comprehensive coverage of the symposium is available online at Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and

Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.