Fatty acid, fat‐soluble vitamin and sterol contents in testis and semen, testis‐somatic index and spermatologic values of broodstock rainbow trout ( Oncorhynchus mykiss ) fed with different levels of omega‐3 fatty acids under regular stripping conditions

Abstract

In this study, the testis and semen fatty acid, fat-soluble vitamin and sterol levels, testis-somatic index and spermatological values were investigated in the broodstock rainbow trout fed with the different levels of omega-3 polyunsaturated fatty acid (PUFA) under the regular stripping conditions. For this purpose, a control and three test diets were prepared. The control, D1, D2 and D3 diets were contained the omega-3 PUFA at 3.14%, 7.84%, 13.63% and 20.54% as a percentage of the total fatty acids respectively. The fish in the experimental groups were fed with these diets for 60 days. The testis-somatic index (3.81–4.50), semen volume (9.30–18.5 ml) and pH (8.05–8.99), initial sperm motility (68.1%–93.7%), duration of 50% sperm motility (141.3–258.9 s), total duration of sperm motility (268.7–489.6 s) and sperm density (9.95–17.5 cells × 109 ml−1) values of the fish fed the control diet were significantly decrease (p < 0.05) depending on decline of the omega-3 PUFA, fat-soluble vitamin and sterol contents in the testis and semen. The omega-3 PUFA (3.40%–14.76% and 3.96%–16.31%), vitamin A (33.9–61.2 ml/mg and 9.12–26.7 ml/mg), D2 (0.10–0.19 ml/mg and 0.04–0.10 ml/mg), D3 (0.75–1.30 ml/mg and 0.06–0.24 ml/mg), alpha-tocopherol (30.1–60.4 ml/mg and 8.93–25.3 ml/mg), K1 (0.30–0.94 ml/mg and 0.03–0.08 ml/mg) and K2 (2.0–3.19 ml/mg and 0.25–0.34 ml/mg) vitamins, cholesterol (1,201–1,588 ml/mg and 330–596 ml/mg), ergosterol (3.12–6.40 ml/mg and 2.10–4.08 ml/mg), stigmasterol (5.57–10.4 ml/mg and 10.2–12.6 ml/mg) and beta-sitosterol (0.20–0.60 ml/mg and 0.14–0.41 ml/mg) contents in the testis and semen of the fish were significantly affected (p < 0.05) by the dietary omega-3 PUFA supplementation. The highest values for these parameters were provided from the fish fed the D2 and D3 diets (p > 0.05), followed by the fish fed the D1 diet (p < 0.05). These results showed that the dietary omega-3 PUFA at 13.63% of the total fatty acids could increase the omega-3 PUFA, fat-soluble vitamin and sterol contents in the testis and semen, the testis-somatic index and spermatologic values of the broodstock rainbow trout under the regular stripping conditions.