Abstract
1. We examined the effects of supplemental dietary vitamin E (Vit E) on semen quality and antioxidative status in male domestic fowls exposed to oxidative stress induced by synthetic glucocorticoid, dexamethasone (DEX) injection. 2. Thirty-six Egyptian local cross males, 42 weeks old, were housed individually in cages in an open-sided building under 16 h light:8 h dark and were provided with commercial feed and water ad libitum. Birds were divided into 4 groups: DEX (4 mg/bird/d), Vit E (200 mg/kg diet), DEX + Vit E (4 mg/bird/d + 200 mg/kg diet, respectively) and control, n = 9. All treatments lasted for 7 continuous days. 3. Oxidative stress induced by injection of DEX (4 mg/bird/d) resulted in decreased sperm count and motility correlated with an increased percentage of dead sperms. Vit E (200 mg/kg diet) enhanced sperm count and viability when supplemented to stress-induced birds, compared to DEX treatment alone. 4. In seminal plasma, low calcium concentration, high lipid peroxidation and reduced activity of glutathione peroxidase were associated with the oxidative stress. Vit E reduced lipid peroxidation in the seminal plasma. 5. In conclusion, excessive supplemental dietary Vit E improved semen quality when cockerels were subjected to stress conditions. It increased both sperm count and motility, reduced the percentage of dead sperm and enhanced the antioxidative status of seminal plasma.