Seasonal sexual activity of Nellore breed bulls and their crosses with Fleckvieh and Chianina: spermatic characteristics

Abstract

Semen was collected by electroejaculation from ten bulls, six Nellore (Bos indicus) breed (GI) and Nelore X Fleckvieh and Chianina (GII), twice a month, during the rainy (June-October 1985) and dry (January-May 1986) seasons. The objective was to determine the effect of seasonal changes on the sexual activity of the bulls. The semen characteristics of volume, sperm motility and individual progressive motility increased (p < 0,05) in the rainy season, were not significant between groups, except the concentration higher (p < 0,05) in the crossbreeds. Spermatic pathology, the small and total defects, did not differ between breeds; however, it was higher (p < 0,05) in the rainy season, a period characterized by a markedly increased temperature. All breeds (Bos taurus X Bos indicus, and Nellore, were affected by seasonally, but without negative effects on spermatic characteristics, which suggests their adaptability to the Central Brazil conditions.