Seasonal and monthly variations in the incidence of morphological abnormalities in bovine spermatozoa in Shika, Zaria, Northern Nigeria

Abstract

Morphological abnormalities of spermatozoa were evaluated in ejaculates of 27 healthy bulls aged between one and a half and three and a half years from January to December of 1982. The year was divided into three seasons: (1) January-April (partly harmattan, dry and hot), (2) May-August (rainy), and (3) September-December (dry and partly harmattan). All the bulls showed seasonal variations in the incidence of sperm-head abnormalities, detached-heads, proximal cytoplasmic droplets and total morphological abnormalities. The means for total morphological abnormalities of the spermatozoa were 21.5%, 10.6% and 11.3% for seasons 1, 2 and 3, respectively ( P<0.01). There were also monthly variations in the incidence of morphological abnormalities of the spermatozoa. The monthly means for total morphological abnormalities of the spermatozoa ranged between 23.74% in March and 4.8% in September ( P<0.001). The results indicated that there were significant seasonal and monthly variations in morphological abnormalities of spermatozoa and that the bulls may be most fertile and best used during the rainy season.