Interactive effects of lipid sources and emulsifiers on the growth performance, digestibility, serum biochemistry, fatty acids, and hepatic oxidative status of juvenile Asian Seabass (Lates calcarifer)

Replacing 50% of a fish oil–soybean oil mixture (FVO) with poultry oil (PO) may offer a cost-effective lipid source for aquafeeds, but its efficacy may depend on dietary formulation and emulsifier supplementation. This study evaluated lysolecithin (LL) and bile acids (BA) in juvenile Asian seabass ( Lates calcarifer ) fed diets containing two basal lipid sources (FVO or PO) combined with four supplementation strategies (control, 0.1% LL, 0.1% BA, or 0.1% LL+BA) in a 2 × 4 factorial design. During a 60-day trial, 360 fish (18.87 ± 0.1 g) were randomly assigned to eight dietary treatments. Lipid source alone did not significantly affect final body weight, weight gain, or specific growth rate; however, significant lipid source × supplementation interactions were observed for these parameters. Under PO-based diets, BA supplementation was associated with greater growth than LL supplementation, whereas growth in the PO+BA group was comparable to that of the FVO control. BA supplementation also improved protein efficiency ratio and protein retention, whereas whole-body crude protein content and apparent protein and lipid digestibility remained unaffected by treatment. BA supplementation was also associated with lower hepatic malondialdehyde levels and, in specific treatment combinations, higher glutathione peroxidase activity, whereas responses of other hepatic and serum biochemical variables varied among treatments. PO increased tissue saturated fatty acid content, whereas LL maintained DHA levels comparable to the control. Overall, 50% replacement of FVO with PO did not significantly impair growth, while the effects of emulsifier supplementation on growth depended on the basal lipid source. BA supplementation was associated with more favorable responses than LL for several growth, protein-utilization, and hepatic oxidative indicators under the specific dietary conditions tested.