FREEZABILITY AND FERTILITY RESULTS WITH UNCENTRIFUGED STALLION SEMEN

The first (1 to 3) sperm-rich fractions of the ejaculate were collecte d from 4 stallions using an open-ended vagina. The volume of the colle cted fractions was 12 +/- 8 ml with a density of 475 +/- 200 million s permatozoa/ml. Before freezing, the semen was diluted with a skim-milk based extender 1 : 1 to 1 : 8 (volume of semen : volume of extender), depending on the initial sperm concentration to achieve a final conce ntration of 100 million/ml. The total number of spermatozoa in an inse mination dose ranged from 0.7 to 1 billion spermatozoa. Within 12 h af ter ovulation, 48 mares were inseminated in 70 cycles. The total singl e-cycle pregnancy rate at day 21 was 24%, but varied from 10% to 33% p er cycle among the stallions.