Growth, reproduction, fatty acid profiles and offspring performance of broodstock yellow catfish Pelteobagrus fulvidraco fed diets with different lipid levels

Parental nutrition plays important roles in reproductive performance and offspring health of broodstock yellow catfish. However, there is a lack of relevant knowledge concerning the broodstocks of many fish species. This study investigated the influence of dietary lipid levels on growth, spawning performance, tissue fatty acid profiles, sex hormone secretion, and offspring health status of yellow catfish (Pelteobagrus fulvidraco). Five experimental diets were designed containing a 7:3 ratio of fish oil and corn oil blends with graded lipid levels (6.3%, 8.2%, 10.8%, 12.2%, and 14.4% by dry weight) and were fed to female broodstock yellow catfish for 8 weeks. The results showed that weight gain, egg diameter, fertilization ratio, and hatching ratio increased initially and then decreased with increasing dietary lipid levels, reaching optimal peaks in the L10.8 group. Broodstock fed a diet with 10.8% lipid obtained the highest 17-beta estradiol concentration. The deposition of highly unsaturated fatty acids in tissues increased initially and then decreased with the increase in dietary lipids, reaching a peak in the 10.8% group. Plasma superoxide dismutase activity and total glutathione content were lowest in fish fed a diet with a 6.3% lipid level, while the contents of malondialdehyde and cortisol in larvae 3 days post-hatching showed an opposite trend, indicating that a low-fat diet reduced the antioxidant capacity of broodstock and induced a stress response that had negative effects on offspring health. Broodstock fed a diet with an appropriate lipid level could increase the expression of antioxidant enzymes by activating the nrf2 signaling pathway. Based on the regression of dietary lipid level and weight gain, reproductive performance, and egg quality of fish, the optimal dietary lipid level was 10.1-11.7% for broodstock yellow catfish.