Abstract
Current experiment was carried out in factorial 2×2 arrangement to study the effects of stress (with or without dexamethasone administration) and addition of dietary selenium (with or without selenium supplementation in the diet) in male broiler breeder on the quality of frozen-thawed sperm under oxidative stress induced by dexamethasone. A total of 24 broiler breeder roosters with the age of 28 weeks were used based on a completely randomized design with four therapeutic approaches (factorial 2×2) and six birds in each approach. The experimental treatments were: 1) basal diet without selenium supplementation and injection of saline (CON), 2) basal diet with dexamethasone injection (4 mg/kg BW, three times every other day for one week), (DEX), 3) without dexamethasone injection and supplementation with 0.3 mg/kg selenium (Sel-Plex), and 4) dexamethasone injection and basal diet supplemented with 0.3 mg/kg of diet selenium (Sel-Plex+Dex). Sperm samples were collected from roosters. Motility, progressive motility, plasma membrane integrity, viability, malondialdehyde concentration and antioxidant parameters were evaluated in fresh and frozen-thawed semen. In spite of non-significant interaction effects, factorial analysis indicated the significant effect of every factor on different experimental parameters in fresh and frozen-thawed semen (P<0.05); The results revealed that total and progressive motility, plasma membrane integrity and viability were lower in DEX group when compared with other treatments (P<0.05). On the other hand, malondialdehyde concentration was higher in DEX group in comparison with Con, Sel-Plex and Sel-Plex+DEX groups (P<0.05). Moreover, total antioxidant capacity, level of glutathione peroxidase and superoxide dismutase were lower in DEX group as compared with other treatments (P<0.05). Our findings indicated that administration of selenium in dexamethasone-receiving roosters (Sel-Plex+DEX) improved the parameters of fresh and frozen-thawed sperm; but the best results were observed in Sel-Plex treatment. Therefore, selenium supplementation in the diet of roosters without dexamethasone injection improved total motility, progressive motility, membrane integrity, viability, malondialdehyde, total antioxidant capacity, glutathione peroxidase and superoxide dismutase pre- and post-freezing. It can be concluded, selenium in organic forms in stressed and non-stressed rooster's diet might improve all motility and antioxidant parameters in fresh and frozen-thawed sperm.