But there is hope. Producers can now identify telltale signs of subfertility in males. Typically, producers have measured breeding success or failure through pregnancy rates, often culling cows rather than bulls when rates drop too low. By using semen motility and morphology, Saacke created a new sperm classification system. Compensable traits include immotile sperm, sperm with tail defects, immature sperm, and sperm with distinctly misshapen heads.
Factors affecting sperm-egg recognition, binding and egg penetration are also compensable traits.
So far, however, no standard tests are available to identify these qualities in sperm. Increasing sperm numbers can compensate for this defect in sperm quality. Producers finding compensable sperm in a bull's semen must increase the number of sperm inseminated. This increases the number of motile sperm, so that the chances of more sperm reaching the egg increase. Identifying sperm with compensable and uncompensable traits may help producers reduce failed pregnancy rates.