Embryo Transfer: Are Efficiencies Improving?
Preparation of females — donors and recips —
is greatest factor affecting ET success.
SIOUX FALLS, S.D. (Dec. 4, 2012) — Commercial embryo transfer (ET) is a well-established and mature industry. The collection and transfer of embryos is practiced in many countries, and the success of ET in well-managed herds is quite high. According to John Hasler of Bioniche Animal Health Inc., the single most important variable affecting success is the level of management applied to the bovine females involved — the embryo donors and the recipients.
Hasler shared his perspective regarding advancements in the practice of ET during the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium Dec. 3-4 in Sioux Falls, S.D. While few significant changes have occurred in recent years, Hasler believes efficiencies of ET are improving.
“In the last 20 years, there hasn’t been much change in the efficacy of superovulation (collection of multiple ova or ‘eggs’ during one ovulation period). We don’t get any more embryos out of a cow,” stated Hasler. “We can do it more efficiently, though. We can collect them more often, and do it on our schedule, thanks to the use of GnRH (gonadotropin-releasing hormone) and CIDR® (controlled internal drug release) technology.”
Hasler said the average number of embryos recovered from superovulation per donor ranges from five to seven. That’s been the case for a couple of decades. However, it’s now possible to “flush” cows every 40 days, instead of the old 65- to 70-day interval between superovulations.
According to Hasler, in vitro production (IVP) has gained popularity in recent years and is being used extensively in Brazil. Instead of flushing embryos from a donor female’s uterus, IVP involves collection of oocytes (unfertilized eggs) by ultrasound-guided ovarian follicle puncture, followed by in vitro fertilization and culture.
“It’s really not new, but its use is increasing in the U.S., too,” offered Hasler, noting that a decade ago, perhaps a few more than 1,000 IVP embryos were produced in the United States. “I expect there will be nearly 40,000 produced in the U.S. by the end of this year.”
Hasler noted that sexed semen is available through nearly all bull studs, but results with ET have not been satisfactory. He cited encouraging results reported by labs in Finland.
“It shows it can work,” stated Hasler.
Cryopreservation has increased in use, according to Hasler, with an estimated 65% of all embryos recovered in the United States being frozen in ethylene glycol. He said pregnancy rates are lower for frozen embryos, as compared to fresh embryos, but the donor-recipient estrous synchrony requirement is a little more relaxed.
Hasler called “technician effect” a huge factor affecting pregnancy rates, but he emphasized how donor and recipient female quality has the biggest impact on success with ET.
Hasler spoke during Tuesday's ARSBC session focused on advancing technologies. Visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation and to view the accompanying PowerPoint and proceedings paper.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and LiveAuctions.tv.
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.