Morphological changes and sperm decapitation as a cause of fertility disorders in breeding stock

Decapitation of spermatozoa was recorded in a young boar as a consequence of epididymitis and in a young dog (mastiff) and a young bull (Brown Swiss breed) as a congenital cause of the subfertility and sterility of the affected animal. Decapitation of spermatozoa as a consequence of an inflammation led to the sterility of the breeding male and affected 52 to 68% of the spermatozoa. The motility of the spermatozoa was reduced considerably (10 to 20%) and the flagella were not observed to move without the heads. In cases of congenital decapitation of spermatozoa, sperm motility in the dog and bull was reduced, but the flagella were observed to move without the heads. Decapitation affected 15 to 42% of the spermatozoa and most frequently it was accompanied by a narrowing of head base and by the presence of a protoplasmic drop, located proximally. Further developmental changes, affecting the flagella of the sperms, were observed in the dog. The mentioned morphological changes led to infertility in the dog and to a substantial reduction of fertility in the bull. After natural mating of the bull with a superovulated cow, the ten eggs obtained included four blastocysts, two were degenerated, and four were unfertilized.