This study describes a new sperm defect in Yorkshire boars. The length of t
he sperm tail is markedly reduced, resulting in a total immotility in all s
permatozoa. At transmission electron microscopy revel, the morphology of th
e midpiece microtubular components area is seriously affected. This boar sp
erm defect differs from the 'tail stump' defect observed in bulls, the tail
s being longer in most spermatozoa than those found in affected bulls. Ther
efore, the term 'short tail' sperm defect is more adequate. The authors obs
erved the first case in 1987. In 1998, this defect became a noteworthy repr
oductive 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 recessi
vely inherited.