Fertility of dairy cattle after artificial insemination with semen frozen in a lipoprotein diluent

Abstract
A lipoprotein separated from egg yolk by centrifugation and column chromatography was used to prepare a diluent containing 2.9% trisodium citrate.cntdot.2H2O (pH 7.0) and 7% glycerol. Ejaculates from Friesian bulls were split between this and 2 control diluents containing egg yolk, glycerol and citrate or lactose and used to inseminate once 1782 unselected Friesian cows. By 16 wk after insemination with semen frozen in the egg yolk-lactose, egg yolk-citrate or lipoprotein-citrate diluents, 66.4, 67.1 and 66.1% of cows, respectively, had not returned to service.