Effect of Zinc Deficiency and Restricted Feeding from Two to Five Months of Age on Reproduction in Holstein Bulls

Open Access
Publisher Website
Google Scholar
Abstract
Reproductive performance in Holstein bulls that had been severely Zinc-deficient from 8 to 21 weeks was compared with that of bulls fed a Zinc-adequate diet both ad libitum and in amounts restricted to somewhat less than those consumed by the deficient animals. The deficiency per se caused a reduction in testicular size at 21 weeks, but the difference disappeared by 64 weeks of age. There were no definite effects of the treatment on volume of semen produced, spermatozoa concentration, total number of spermatozoa produced, rate of motility, or percentage motile spermatozoa during a once per week collection period for 8 weeks, nor in a partial-exhaustion trial of 14 collections at 10-min. intervals. Histological differences in the testicles at the end of the study were not large and not highly correlated with most measures of semen quality. Thus, in contrast to previous experiments with rats, the Zn deficiency did not greatly affect reproductive performance. Restricting the amount of control diet to 58% of that fed, the ad libitum-fed controls from 8 to 21 wk. of age did not significantly affect any of the reproductive characteristics measured.
Keywords