EFFECT OF SEMINAL PLASMA AND EGG-YOLK ON MOTION CHARACTERISTICS OF COOLED STALLION SPERMATOZOA

This study on extended, cooled spermatozoa was designed to determine 1) the concentration of seminal plasma required for the preservation of sperm motility, 2) whether the addition of egg yolk to a milk based semen extender improved the maintenance of sperm motility, and 3) whether there was a beneficial interaction of seminal plasma and egg yolk in the maintenance of sperm motility. For all experiments, semen was centrifuged for the removal or reduction of seminal plasma and spermatozoa were resuspended in a nonfat, dried skim milk - glucose extender. In Experiment 1, removal of all seminal plasma from spermatozoa and suspension in the extender resulted in a significant (P<0.05) depression in sperm motion characteristics by 24 hours of cooled storage. Whereas, the suspension of spermatozoa in the extender containing 5 to 20% of seminal plasma was sufficient to maintain motion characteristics over 72 hours of cooled storage. In Experiment 2, the removal of all seminal plasma from spermatozoa and suspension in the extender containing 4 to 16% of clarified egg yolk significantly (P<0.05) improved sperm motion characteristics over 48 hours of cooled storage compared to those of spermatozoa devoid of seminal plasma suspended in the extender without egg yolk. There were no differences in motion characteristics for spermatozoa suspended in extender containing either 4, 8 or 16% of clarified egg yolk. In Experiment 3, the retention of 5% seminal plasma following centrifugation of semen and resuspension of spermatozoa in the extender resulted in similar sperm motion characteristics over 72 hours of cooled storage to those of spermatozoa in uncentrifuged semen diluted with the extender. The removal of seminal plasma from spermatozoa and suspension in the extender containing 4% of clarified egg yolk maintained significantly (P<0.05) higher percentages of motile and progressively motile spermatozoa beginning at 12 hours of cooled storage when compared to that of spermatozoa in semen diluted in thc extender without thc removal of seminal plasma. However, motion characteristics of spermatozoa suspended in extender containing egg yolk were not dissimilar than those for spermatozoa retaining 5% seminal plasma in the extender without the addition of egg yolk. There appeared to be no additional benefit of the retention of 5% seminal plasma and the addition of 4% egg yolk in thc extender for the maintenance of sperm motion characteristics. The resuspension of spermatozoa following centrifugation of semen in a nonfat, dried skim milk - glucose extender containing clarified egg yolk may improve the maintenance of cooled sperm motility.