Organic zinc supplementation in the dry season in nelore bulls and its effect on spermiogram.

The objective of this study was to evaluate the effect of a diet supplementation with 500mg organic zinc (Zn) on sperm morphological characteristics (mass motility, individual motility, and sperm livability) as well as minor and major sperm defects in Nelore bulls during the dry season of 2010, the pluviometric precipitation during the experimental period which occurred from April to October, was 69mm from April to August. Thirty-six bulls were selected and divided into two groups of 18 bulls. They were fed the supplemented diet for 180 days. The animals in the first group (G1) were supplemented with an average of 48,89ppm/kg MS Zn, and the animals in the second group (G2) were supplemented with 115,09ppm/kg DM Zn. Data was analyzed with Minitab 13.0. The results of the morphological characteristic of sperm G1 and G2 were higher at 180 days compared to Day zero, especially in vigor and mass motility, with only statistically significant difference in each group, not differentiating between groups. The organic zinc did not affect the morphological characteristic of sperm in Nellore bulls in the dry season.