Glycosaminoglycans as probes to monitor differences in fertility of bulls.

Recently high molecular weight polysaccharides termed glycosaminoglycans have been successfully used to capacitate bull sperm in vitro. Heparin, one class of glycosaminoglycan, binds to sperm in a manner typical of receptor-ligand interaction. Bulls with above average nonreturn rates produce sperm that exhibit a higher frequency of acrosome reactions when exposed to glycosaminoglycans in vitro. In addition, the binding affinity that sperm possess for heparin is related to nonreturn rates of bulls, and binding affinity decreases in semen samples with a high frequency of abnormal sperm. Glycosaminoglycans may be useful probes to evaluate in vitro cellular changes that sperm complete prior to fertilization and serve as markers of sperm membrane defects, which ultimately affect fertility of a bull.