A decapitated sperm defect in two sterile Hereford bulls.

Two almost identical cases of sterility in young Hereford bulls have been investigated. Semen samples sent to the laboratory showed normal sperm concentradition and abnormal sperm morphology. In 80-95% of the sperm cells, head and tail were separated, and similar to what has been found in the 'decapitated sperm defect' in the Guernsey breed, a high percentage of the loose tails were able to perform active movements. A third characteristic was a proximal bending or curling of the loose tail around the cytoplasmic droplet, a detail which by lower magnification might be mistaken for a mini-head. The possible heredity of the defect is discussed.