Interactive influences of dietary selenium and oxidized fish oil on growth, nutritional composition, muscle development, antioxidant responses and selenoprotein expression in the muscle of yellow catfish Pelteobagrus fulvidraco

The current study is conducted to determine the influences of dietary selenium (Se) and oxidized fish oil (OFO) on growth, nutritional composition, muscle development, antioxidant responses and selenoprotein expression in the muscle of yellow catfish. We used the 2 x 2 factorial experimental design, which included two dietary Se levels at 0.25 (adequate) and 0.5 (high) mg Se/kg diets, and each Se level had fresh fish oil (FFO) and OFO, respectively. The experiment continued for 10 weeks. Compared to FFO group, dietary OFO reduced final body weight (FBW), specific growth rate (SGR) and weight gain (WG), and the contents of n-6 polyunsaturated fatty acid (PUFA), 18: 2n-6, 20: 4n-6, n-3 PUFA, 20: 5n-3, 22: 6n-3 and total PUFA, the diameters of muscle fibers >80 & mu;m, mRNA expression of mef2d, myf5, myod, s6kb and mTOR, and the ratio of p-mTOR to mTOR protein expression, but increased feed conversion rate (FCR), muscle lipid content, malic enzyme (ME) and isocitrate dehydrogenase (ICDH) activities, the number of the muscle fiber with the diameter lower than 50 & mu;m; high dietary Se addition alleviated OFO- induced variations of these indices mentioned above. Dietary OFO also reduced muscle catalase (CAT) and glutathione peroxidase (GPX) activities and total antioxidant capacity (AOC), and mRNA expression of gpx1, gpx2, gpx3, selenoe, selenok and selenos, but increased total superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and NRF2 protein expression, and high dietary Se addition alleviated OFO-induced changes of these parameters involved in antioxidant responses and selenoprotein expression in the muscle of yellow catfish. Based on these observations above, dietary Se addition alleviated OFO-induced lipogenesis, and reversed the OFO-induced inhibition of muscle growth and development, and oxidative damage of muscle. Our study provides new mechanistic insights into the Se and OFO interaction in fish. Statement of relevance: The biological basis through which dietary OFO and Se diets interacted to affect muscle metabolism and physiology is scarce. Our study indicated that dietary Se could alleviate OFO-induced negative effects on muscle metabolism and physiology, which will be helpful to the feed formulation and fish farm.

Automated summary

This study investigated the effects of dietary selenium and oxidized fish oil on growth, nutritional composition, muscle development, antioxidant responses, and selenoprotein expression in yellow catfish. The results showed that oxidized fish oil had negative effects on growth and muscle development, but high dietary selenium levels alleviated these effects. Additionally, oxidized fish oil reduced the antioxidant capacity of fish muscle, while dietary selenium mitigated this effect. These findings are important for feed formulation and fish farming.