Predicting fertility of dairy bulls by inducing acrosome reactions in sperm with chondroitin sulfates.

Bull spermatozoa were incubated with 0 or 50 micrograms/ml chondroitin sulfates to induce acrosome reactions in vitro. Data were computed as percent increase in acrosome reactions elicited by chondroitin sulfates compared with control samples for each replicate. Data from 8 bulls with known nonreturn rates served as basis to predict nonreturn rates of 18 bulls entering an AI lineup. The average assay CV was 16.1% for all 26 bulls. Correlation coefficients of polynomial regression lines computed between actual nonreturn rates and percent increases in acrosome reactions in response to chondroitin sulfates were .98 and .81 for the 8 reference bulls and combined data of all 26 bulls, respectively. It is concluded that a laboratory assay using chondroitin sulfates to induce acrosome reactions in sperm can be used to predict relative fertility of bulls.