Embryo survival in mature Romney ewes relative to live weight and face cover

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Abstract
In Experiment 1 fertilised eggs were transplanted at the rate of 1, 2, or 4 per recipient ewe and these animals were autopsied in early pregnancy. In Experiment 2 ewes were mated to fertile rams and autopsied 18–30 days later. Some of these ewes had not conceived to egg transfer (Expt 1). Transfer of 1, 2, or 4 eggs did not affect the percentage of ewes which became pregnant. An ovum had a greater chance of surviving if transferred singly rather than as one of a multiple number of eggs. The number of corpora lutea (lor 2) did not affect the rate of survival of transferred ova or survival of ova in mated ewes. No significant relationship existed between live weight of the ewe and survival of ova. Face cover was related (P < 0.01) to rate of survival of ova among ewes transplanted with 2 eggs each, but no clear effect was apparent in the other ewes after egg transfer or in the mated ewes.