Effects of seminal plasma and of its removal and of egg yolk in the diluent on the survival of fresh and frozen-thawed spermatozoa of the Angora goat.

After twofold dilution with Tris-glucose medium, buck seminal plasma was a poorer milieu than ram seminal plasma for the maintenance of viability of freshly collected spermatozoa of both species. Egg yolk (9% v/v) in the diluted buck seminal plasma caused coagulation of the medium coupled with death of spermatozoa after 2 h incubation at 37 degrees C. Removal of seminal plasma by centrifugation (washing) of buck semen was beneficial for the survival of spermatozoa after freeze-thawing, but the effect depended on the intensity of washing. When the semen was diluted 6- or 11-fold, double washing was more effective than single washing. However, the efficiency of the latter method, after 21-fold dilution, was similar to that of double washing at 11-fold extension. Survival of washed spermatozoa was better when the resuspending-freezing medium contained 1.5-12% (v/v) egg yolk than no egg yolk. Egg yolk concentration higher than 1.5% (v/v) depressed the post-thawing survival of non-washed spermatozoa.