Optimum dietary lipid requirement of Pangasianodon hypophthalmus juveniles in relation to growth, fatty acid profile, body indices and digestive enzyme activity

Abstract

The present experimental trial was conducted to determine the optimal dietary lipidrequirement of juveniles of Pangasianodon hypophthalmus (Sauvage, 1878) commonlyreferred to as the striped catfish using completely randomized design (CRD). Purified dietswith five different dietary lipid levels (3, 6, 9, 12 and 15%); fish oil/sunflower oil (1:1) wereused to feed triplicate groups of Pangasius with initial mean weight of 13.54–14.12 g twice aday for 8 weeks. The highest weight gain (P< 0.05) was observed in fish fed with 9 and 12%lipid diets, followed by diet with 6% lipid, then by 15% lipid diet, and the lowest weight gainwas observed in fish fed with 3% lipid. Other parameters such as specific growth rate (SGR),feed efficiency (FE) and protein efficiency ratio (PER) showed the same trend of weight gain.The hepatosomatic index (HSI), viscerosomatic index (VSI) and intraperitoneal fat (IPF)values increased with the increase of dietary lipid level. The feed conversion ratio (FCR)(P< 0.05) showed significant effects (P< 0.05) with variations in dietary lipid levels. Theminimum FCR (1.95) was observed at 9% lipid inclusion-fed fishes and maximum FCR (3.53)was noticed at 3% lipid inclusion fed fishes. Higher and lower digestive enzyme activities wererespectively observed in 9 and 15% lipid diets. The muscle fatty acid profile also varied withdifferent dietary lipid levels. The higher level of ω-3, ω-6 fatty acid contents was recorded inthe muscle of fish fed with 9% lipid diet, and lower level of fatty acid content was recorded infish fed with 3% lipid diet. However, using second-order polynomial regression analysis, theoptimal dietary lipid requirement of P. hypophthalmus juveniles was found to be 10.1%