THE COMMERCIAL APPLICATION OF EMBRYO SPLITTING IN BEEF-CATTLE

Pregnancy data was reviewed, retrospectively, for demi-embryos transferred over a forty-three month period of time in a commerical embryo transfer environment. Embryos collected from 435 superovulated beef cows in ten different geographic regions of the USA resulted in 994 embryos selected for bisection. Of the 1988 demi-embryos transferred, 997 pregnancies were created, accomplishing an overall pregnancy rate of 50.2%. Embryos selected for the bisection procedure were excellent quality compacted morula, early blastocysts, and blastocysts. Pregnancy rates for these stages were 51.6%, 47.3%, and 44.4%, respectively. Embryos selected for bisection were collected 7.5, 7.0, 6.5 or 6.0 days after estrus and resulted in pregnancy rates of 52.5%, 50.0%, 51.5% and 48.5%, respectively. Embryos producing a pregnancy from each demi-embryo (split-twins) represented 27.7% of the total; while 44.8% of the embryos selected produced only one pregnancy and 27.5% of the embryos selected failed to produce a pregnancy. Embryo splitting was undertaken for the purpose of increasing the number of pregnancies from individual donor cow collections. Client expectations were satisfied and exceeded with pregnancies resulting from 72.4% of the embryos selected.