Semen indices, growth response and sperm reserve of male rabbits fed zinc supplemented diets

This study was carried out to assess the effect of dietary levels of zinc on semen indices, growth parameters and testicular sperm reserve of heterogeneous stock of male rabbits. Twenty male rabbits aged 6 mo old were randomly allotted to four groups of five males each and fed diets containing 0, 50, 100 and 150 mg of zinc gluconate per kg diet, respectively, for eight weeks. Semen was collected from the males weekly using an artificial vagina and semen volume (mL), spermatozoa motility (%), sperm concentration (×108/mL) and live sperm cells (%) were assessed. Seminal plasma was separated from the semen by centrifugation, and its zinc concentration was determined using atomic absorption spectrometry. The weights of the males were taken weekly, and the daily feed intake was recorded. At the end of the feeding trial, the rabbits were stunned and slaughtered; the testes and epididymis were carefully removed and homogenised to determine sperm reserves using standard procedure. The result showed that semen indices were not significantly influenced by the dietary levels of zinc gluconate. Seminal zinc concentration was significantly higher in males fed 100 and 150 mg of zinc per kg compared to those in the control group. A higher body weight gain (454±50.3 g), testes weight (6.23±0.25 g) and epididymis weight (1.63±0.59 g) was recorded in males fed diet supplemented with 50 mg of Zinc gluconate per kg. No significant effect of dietary zinc supplementation was recorded in testicular sperm reserve. Epididymal sperm reserve was significantly higher in males fed the diets including 100 and 150 mg of zinc gluconate per kg. In conclusion, dietary levels of zinc gluconate did not improve semen quality and growth indices but increased seminal zinc concentration, which could result in improved prostate health in the heterogeneous stock of male rabbits in the tropics.