EFFECT OF DIFFERENT PROTEIN SUPPLEMENTS ON MOTILITY AND PLASMA-MEMBRANE INTEGRITY OF FROZEN-THAWED STALLION SPERMATOZOA

Three experiments were conducted to evaluate the effect of different m acromolecule components (egg yolk, skim milk, and BSA) in a widely emp loyed extender for cryopreservation of horse semen. Spermatozoal motil ity (MOT) and the percentage of spermatozoa with an intact plasma memb rane (IPM) were evaluated in frozen-thawed samples. In the first exper iment (four Draft Horse stallions, four ejaculates each) a standard fr eezing extender containing 20% whole egg yolk was modified by replacin g extender components (glucose-EDTA solution, 11% lactose solution) wi th an increasing volume of a skim milk diluent (0, 25, 50, and 75%, v/ v). The best results were obtained with an extender containing 75% (v/ v) skim milk solution (MOT 24.7%; IPM 46.6%). This extender was furthe r tested in Experiment 2 (three Draft Horse stallions, four ejaculates each) by varying the amount of egg yolk (10 or 20%) and by addition o f 5% BSA. Neither the amount of egg yolk nor the addition of BSA signi ficantly influenced postthaw results. Selected extenders from the prev ious experiments were tested in Experiment 3 (three stallions, four ej aculates each). Again, a mixture of 20% whole egg yolk and a skim milk solution provided the best results (MOT 41.7%; IPM 54.2%). The result s of this study indicate that the inclusion of different sources of ma cromolecules (e.g., egg yolk and skim milk) can improve motility and p lasma membrane integrity of frozen-thawed horse spermatozoa. (C) 1995 Academic Press, Inc.