Embryo transfer in fertile and infertile cows

Pregnancy rates were compared between fertile and infertile donors in an embryo transfer program. Non-surgical embryo transfer techniques were utilized for examination of uterine contents and collection of ova. Recovered embryos were transferred surgically into suitable recipients. Three groups of donors were included in this investigation: a) fertile; b) infertile, due to known causes (diagnosed); c) infertile, due to unknown causes (undiagnosed). There were 11.3, 6.6 and 8.0 corpora lutea; 6.8, 1.2 and 1.0 fertilized ova; 3.6, 0.8 and 0.4 pregnancies per superovulation for the fertile, diagnosed and undiagnosed groups, respectively. In 23 months, unsuperovulated, fertile, diagnosed and undiagnosed donors yielded 17, 15 and 9 fertilized ova which resulted in 15, 13, and 3 pregnancies, respectively. Donors treated for uterine infections, adhesions or cystic ovaries prior to superovulation responded with 10.1, 7.6 and 4.1 corpora lutea; 1.9, 4.0 and 0.3 fertilized ova; 1.1, 3.3 and 0.2 pregnancies per superovulation, respectively. Relatively few viable embryos were recovered from donors with chronic cystic ovaries or from infertile cows of unknown etiology. Infertile donors, when compared to fertile donors, were unproductive when used for embryo transfer.