Fertility of Bull Semen Frozen in Skim Milk Diluent

In Victoria the usual diluent for deep frozen bull semen consists of a mixture of egg yolk, sodium citrate and glycerol. The semen is equilibrated in this mixture for 17 hours prior to freezing. O’Dell and Almquist (1957), and Amman and Almquist (1957) found that survival of spermatozoa as assessed by motility was increased when the semen was diluted with a mixture of glycerol, fructose and skim milk instead of egg yolk-citrate diluent. When diluted with this mixture best survival of spermatozoa was obtained with a very short period of equilibration. The purpose of the present observations was to obtain information on the relative conception rates as distinct from spermatozoa1 motility with the two types of diluents, and to determine whether dilution with the skim milk mixture could be adapted to facilitate the processing of semen at a commercial centre, in this case the Victorian Artificial Breeders’ Co-operative, Bacchus Marsh.