Relationship of Sire Fertility to Acrosome-Reacted and Motile Spermatozoa After Treatment with Liposomes

Abstract

The relationship between bull nonreturn rate and percent acrosome-reacted and percent motile sperm treated with 24.8, 34.8, and 44.8 μM dilauroylphos-phatidylcholine liposomes was examined. Frozen-thawed spermatozoa from six bulls, with fertility ranging from 64 to 78%, were incubated at 39°C with the liposomes for 0, 7, and 15 min. Bulls differed in percentages of motile sperm, and this decreased over time, especially at the highest concentration of lipids (44.8 μM). Bulls differed initially in their percentage of sperm with intact acrosomes and in their linear rate of increase in percent acrosome-reacted sperm. At 24.8 μM of lipid the rate of increase was nearly linear, whereas at higher concentrations the maximum acrosome reaction was approached during short incubations. The variables 1) decline in percent motile sperm and 2) increase in percent acrosome-reacted sperm, used singly, predicted fertility most accurately when measured on sperm treated with 44.8 and 24.8 μM of lipids, respectively. However, the highest relationship (R² ≥ .97) was established by combining the acrosome and motility measurements of sperm exposed to 34.8 μM of lipids. Thus, potential fertility of bulls may be predicted by application of this assay to frozen-thawed semen.