LIPID AND ANTIOXIDANT COMPOSITION OF CHICKEN SEMEN AND ITS SUSCEPTIBILITY TO PEROXIDATION

The antioxidant composition of the chicken seminal plasma and spermato zoa and the effect of sperm storage on fatty acid composition of the p hospholipid fraction were investigated. Chicken semen displayed range of antioxidants including vitamin E, ascorbic acid, glutathione, super oxide dismutase and glutathione peroxidase. Ascorbic acid was almost e qually distributed between seminal plasma and spermatozoa. In contrast , reduced glutathione and vitamin E were located mainly in the spermat ozoa. The main form of glutathione peroxidase (GSH-Px) was Se-dependen t GSH-Px, which was found in both the seminal plasma and the spermatoz oa. On the other hand, superoxide dismutase (SOD) was mainly located ( 67%) in the spermatozoa. Cu,Zn-SOD was found only in seminal plasma bu t both forms of the enzyme (Cu,Zn-SOD and Mn-SOD) were found in sperma tozoa. The toxic effect of H2O2 and cumene hydroperoxide on sperm moti lity was determined. Sperm incubation for 12 hours at 20 degrees C was associated with a significant decrease in the proportion of 22:4n-6 i n the phospholipid fraction. The inclusion of Fe2+ in the incubation m edium at 37 degrees C further increased the rate of lipid peroxidation as indicated by the significant decrease in the proportion of 20:4n-6 , 22:4n-6, 22:5n-3 and 22:6n-3 in the phospholipid. Free radical-trapp ing activity of seminal plasma was measured. Possible mechanisms invol ved in sperm antioxidant protection are discussed.