Bile acid improves growth, lipid utilization and antioxidative status of genetically improved farmed tilapia (Oreochromis niloticus) fed with varying protein-lipid diets reared in inland saline water

A 60-day feeding trial was conducted to find out the effect of bile acid supplemented diets with varying protein and lipid levels on growth performance, body composition, antioxidant status and physio-biochemical responses of genetically improved farmed tilapia (GIFT) juveniles reared in inland saline water (ISW) of 10 ppt. Three hetero-nitrogenous (38–32% crude protein, CP), hetero-lipidic (8–14% lipid) and hetero-caloric (409–439 Kcal digestible energy/100 g) diets were supplemented with three levels (0%, 0.05% and 0.1%) of bile acid to prepare nine experimental diets viz. P38L8B0 (38% CP, 8% lipid and 0% bile acid), P38L8B0.05 (38% CP, 8% lipid and 0.05% bile acid), P38L8B0.1 (38% CP, 8% lipid and 0.1% bile acid), P35L11B0 (35% CP, 11% lipid and 0% bile acid), P35L11B0.05 (35% CP, 11% lipid and 0.05% bile acid), P35L11B0.1 (35% CP, 11% lipid and 0.1% bile acid), P32L14B0 (32% CP, 14% lipid and 0% bile acid), P32L14B0.05 (32% CP, 14% lipid and 0.05% bile acid) and P32L14B0.1 (32% CP, 14% lipid and 0.1% bile acid). Four hundred and five acclimated GIFT juveniles (2.51 ± 0.01 g) were randomly distributed in nine treatment groups in triplicate (stocking density 15 fish/tank, 300 L) following 3 × 3 factorial design. Results indicated that body lipid, feed conversation ratio (FCR), amylase and lipase activities, gill and liver superoxide dismutase (SOD) and catalase (CAT) activities and serum glucose (GLU), total protein, triacylglycerol (TAG), total cholesterol (T-CHO), and low density lipoprotein cholesterol (LDL-CHO) were significantly (p < 0.05) increased and weight gain percentage (WG%), specific growth rate (SGR), protease activity and high density lipoprotein cholesterol (HDL-CHO) were significantly (p < 0.05) decreased with increasing dietary lipid levels and more pronounced effect was found in fish fed 32% protein and 14% lipid. Dietary bile acid significantly (p < 0.05) increased WG%, SGR, protein efficiency ratio, lipase activity and HDL-CHO and significantly (p < 0.05) decreased FCR, gill and liver SOD and CAT activities and serum GLU, TAG, T-CHO, and LDL-CHO with more pronounced effect by 0.05% dietary bile acid. In conclusion, feeding of 35% crude protein, 11% lipid and 0.05% bile acid can cause better growth performance, antioxidant status and physio-biochemical responses of GIFT juveniles reared in ISW of 10 ppt. This information will be useful in formulating the bile acid supplemented eco-friendly low protein high lipid (LPHL) feed for profitable culture of GIFT in ISW.