The Hereditary ‘Short Tail’ Sperm Defect ‐ A New Reproductive Problem in Yorkshire Boars

Contents This study describes a new sperm defect in Yorkshire boars. The length of the sperm tail is markedly reduced, resulting in a total immotility in all spermatozoa. At transmission electron microscopy level, the morphology of the midpiece microtubular components area is seriously affected. This boar sperm defect differs from the ‘tail stump’ defect observed in bulls, the tails being longer in most spermatozoa than those found in affected bulls. Therefore, the term ‘short tail’ sperm defect is more adequate. The authors observed the first case in 1987. In 1998, this defect became a noteworthy reproductive problem, when it was observed in nine boars intended for breeding. In one litter, three littermates were affected with the ‘short tail’ sperm defect. At the present time the authors believe that the defect is recessively inherited.