IntroductionThe increasing use of artificial insemination (AI) in poultry industry emphasizes the need for good quality sperm distribution. A proper evaluation of semen prior to AI or storage is very important to avoid losses in fertility. Because semen evaluation is extremely important for semen storage and AI programs, a rapid, economical, objective and fertility predictive method of semen evaluation would be beneficial for the poultry industry protocols. Determination of antioxidant enzymes concentration in semen has been practiced for a long time (Peters, 2008).Lipids are a basic component of semen, contributing to the membrane structure of spermatozoa, the metabolism of the sperm cells, and their ability to capacitate and fertilize the female gamete. In birds, the lipid composition of spermatozoa has an influence on fertility (Ansah and Buckland, 1982). El-Saadany (2002) reported that increasing storage time of diluted semen from local chicken breed for 0, 24, 48 and 72 hr decreased significantly (P<0.01) the fertility rate (FR) by 5.12, 9.55 and 12.53%, respectively. Shamiah et al. (2017) reported that GSH supplementation in semen extender significantly (P<0.05) increased FR. Semen supplemented with 0.2 mM GSH (74.5%) showed higher FR than those supplemented with 0.6 mM GSH or free semen (59.9 and 59.2%, respectively).Sperm cells have a high content of unsaturated T HIS STUDY was carried out to evaluate the effect of glutathione (GSH) supplementation at levels of 0.0 (control), 0.2, 0.4 and 0.6 mM to diluted semen stored for 0, 24, 48 and 72 hr at 5°C, on antioxidant enzymes activities in seminal plasma, semen characteristics and fertility rate (FR) of cocks Inshas strain. Supplementation of 0.6 mM GSH to the diluted cocks semen significantly increased (P<0.05) the concentration of alkaline phosphatase (ALP) (40.2 u/ml) compared to other treatments (33.0, 27.8 and 28.3 u/ml). Superoxide dismutase (SOD) concentration in seminal plasma was not significantly affected (P<0.05) by different levels of GSH, storage period or interaction between levels of GSH and storage period. Glutathione peroxidase (GSH-Px) concentration in seminal plasma was not affected by different levels of GSH (P<0.05). Total antioxidant capacity (TACO) in seminal plasma was significantly affected (P<0.05) by different levels of GSH, storage period or interaction between them. There was a positive correlation (r=0.089 and r = 0.168) between SOD concentration and (GSH-Px and TAOC) concentration, but negative correlation (r=-0.119) with ALP concentration. Positive insignificant correlation between (ALP, SOD and TACO) concentration in seminal plasma with the progressive motility, live sperm, curled tail and fertility, while positive significant correlation between GSH-Px concentration with progressive motility, curled tail and fertility. It could be concluded that the addition of GSH to semen extender of cockerels especially at levels 0.2 mM improved the antioxidant enzymes activities, which play a vital role in lowering the deleterious effe...
