Induction of acrosome reactions by chondroitin sulfates in vitro corresponds to nonreturn rates of dairy bulls.

This study was designed to relate nonreturn rates to induction of acrosome reactions by the glycosaminoglycan chondroitin sulfate. Semen samples were obtained from four bulls above and four bulls below 65% nonreturn. Washed sperm from four ejaculates from each bull were incubated for 9 h with 0, 1, 10, or 50 micrograms/ml chondroitin sulfate. Acrosome reactions were evaluated by microscopy with Nomarski optics. Sperm from the higher fertility bulls exhibited significantly higher percentages of acrosome reactions to 10 and 50 micrograms/ml of chondroitin sulfate, and the slope of their dose-response regression line was significantly greater.