Effects of dietary fish oil replacement with rice bran oil on growth performance, serum biochemical index, antioxidant capacity, lipid metabolism and inflammatory response of large yellow croaker (Larimichthys crocea) juveniles

Fish oil (FO) replacement has become a top priority with the increasing growth of aquaculture and the decline of FO production. Dietary rice bran oil (RBO) has been marked with good application prospects and development potential in humans and terrestrial animals. Hence, this study was geared towards ascertaining the effects of replacing dietary FO with RBO in fish feeds. In this study, a 74-day feeding trial was conducted with large yellow croaker (Larimichthys crocea) juveniles to ascertain the effects of dietary FO replaced by different levels (0%, 25%, 50%, 75% and 100%) of RBO. Each diet was randomly fed to triplicate groups of large yellow croaker juveniles (120 fish per group) with an initial mean body weight of 13.02 +/- 0.02 g. Fish fed with dietary RBO 25% showed significantly higher final body weight, weight gain rate, specific growth rate, and feed intake compared to other treatments. Also, fish fed diets with RBO showed significantly higher antioxidant capacity compared to the control. Interestingly, fish fed with RBO 25% diet showed a significantly improved serum lipid profile when compared to the control. Moreover, the hepatic mRNA expression of sterol regulatory element-binding protein-1 (srebp-1), and fatty acid synthase (fas) was significantly upregulated in RBO 25% replacement, while peroxisome proliferator-activated receptor alpha (ppar alpha), was significantly suppressed in fish fed RBO 100% compared to the control. Furthermore, fish fed RBO 100% had significantly increased Interleukin-1 beta (il-1/i), Tumour necrosis factor-alpha (tnf-alpha), and Interferon-gamma (ifn-gamma), and significantly decreased transcript levels of Interleukin-10 (il-10). Therefore, the results of the present study showed that RBO could promote the performance of large yellow croaker juveniles, by improving the growth indexes, serum biochemical properties, antioxidant capacity, and alleviating liver inflammation.