Effect of Dietary Supplementation with Omega-3 Fatty Acids on Seminal Plasma Arginase Activity and Semen Quality Parameters in Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792)

Background: This study was conducted to determine the effect of various fatty acid ratios added to diets of rainbow trout (Oncorhynchus mykiss, Walbaum) on some sperm parameters and parameters related to arginase activity. Methods: A total of 99 male rainbow trout were used in this study, with the fish averaging 3 years old. Semen was collected by abdominal massage. Four different experimental groups were created in the study: a control group without n-3 series fatty acids added to their diets, and groups with n-3 series fatty acids added at ratios of 1% (D1), 2% (D2), and 3% (D3), respectively. Results: While no significant difference in semen volume was observed between the D1 and D3 groups and the control group, semen volume was significantly higher in the D2 group. Compared with the control group, the time required for sperm motility to decline to both 50% and 0% was significantly prolonged in the D1 and D3 groups. Seminal plasma arginase activity did not differ significantly in the D2 and D3 groups compared with the control group but was significantly higher in the D1 group. Conclusions: Consequently, considering the doses used in the study, fatty acid supplementation was found to lead to changes in sperm quality parameters, specifically volume (only 2%) and arginase activity (only 1%). Given that the rate of decrease in sperm motility was later in groups D1 and D2, it was concluded that the added fatty acids may be beneficial.