Congenital impotentia genarandi

Some bulls which are otherwise normal and healthy produce semen containing spermatozoa with specific morphological abnormalities together with absence or reduced fertilizing power. Spermatozoa may contain heads detached from tails. Some bulls may produce a very high percentage of deformed sperms with reflected tail lying within the plasma  membrane of the head. Some bulls persistently show a high percentage of various sperm abnormalities in their semen and are almost sterile.