Survival of in vitro-produced cattle embryos from embryo transfer to weaning

D.C. SMEATON, L.T. McGOWAN, M.L. SCOTT, H.R. TERVIT AND C.A. CAMERON

AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand

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NZSAP 2003 Abstract No. 15 Proceedings of the New Zealand Society of Animal Production 63: 57-60

New reproductive technologies present both the beef and dairy industries of New Zealand with numerous opportunities. A key factor in the successful use of these technologies is the reproductive rate obtained from their use.

MOET (multiple ovulation and embryo transfer) is a fairly well established procedure to achieve pregnancy by embryo transfer. As an alternative, harvesting of oocytes, in vitro fertilization, culture, and subsequent embryo transfer (IVP-ET), also has potential. The technology is still relatively new and pregnancy rates of 30% have been reported. This is at least 10% lower than that achieved with MOET. As part of another project, approximately 400 recipient cows, in each of three years, were subject to ET using fresh IVP embryos. Pregnancy rates to calving, per embryo transferred, averaged 40, 44 and 33% in 1999, 2000 and 2001 respectively. Within years, average pregnancy rate varied from less than 20% to over 50% depending on recipient source (P<0.05), breed (P<0.01) and condition score (P<0.05). Once cows could be detected pregnant, at about 50 days after embryo transfer, they tended to stay pregnant through to calving. Neither embryo breed nor the type of oestrus-synchronizing device had a significant effect on pregnancy rate.

Keywords: NZSAPAB; cattle; embryo transfer; in vitro embryo; embryo survival; pregnancy; calving

Last Updated 8/07/2004