In vitro production of cattle embryos: Use in beef twinning
programmes.
P.A. Pugh, J.G. Thompson, L.T. McGowan, W.H. McMillan, H.R.
Tervit.
AgResearch, Ruakura Agricultural Research Centre, Private Bag 3123,
Hamilton, New Zealand.
Proceedings of the New Zealand Society of Animal Production 1994,
54: 351-352
This study investigated the survival of in vitro derived embryos as
single or twin pregnancies following their twin transfer to recipient cows.
Abattoir-derived oocytes were matured, fertilised and then cultured for 6-7 days
using our standard laboratory procedures. One hundred and forty good quality late
morula and blastocysts were transferred non-surgically, in pairs, to recipient
cows on day 7 of the oestrous cycle (day 0 = oestrus). Recipients were
monitored by ultrasound for pregnancy up to Day 60 and embryo survival was
determined. While 57 (81%) of recipients did not show oestrus by day 21, only
39 (56%) were pregnant on day 35 and 30 (77%) of the pregnancies were twins
(embryo survival; 57%). Increasing stage of gestation was associated with a
decrease in pregnancy rate, twin pregnancies and embryo survival (46%, 37%
and 31%, respectively) on day 60. The results show that while high initial
pregnancy rates can be established following the transfer of two in vitro
derived embryos, embryo survival drops during early pregnancy. Current research
efforts are investigating factors that may influence early embryo survival in
cattle.
Keywords: NZSAPAB;
Twinning rates; early pregnancy; IVP embryos
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Last Updated 25-01-1997
