Inland saline culture of GIFT (Oreochromis niloticus) juveniles: effect of graded levels of lipid on growth and haemato-biochemical responses.

60-days trial was performed to study the effect of inland saline water (ISW) at 10ppt salinity on lipid requirement of Genetically Improved Farmed Tilapia (GIFT) juveniles. Six purified iso-nitrogenous (37% crude protein) and hetero-caloric (380-430 Kcal DE/100 g) diets having graded levels of dietary lipid viz., 4, 6, 8, 10, 12 and 14% were prepared. Two hundred and seventy acclimated GIFT juveniles (1.90 ± 0.1 g) were randomly distributed (15 fish per 300 L tank) into six different treatments viz., T4, T6, T8, T10, T12 and T14 in triplicates. The increase in dietary lipid resulted in an increase in body lipid and a diminution in moisture levels in fish. There was a significant (p < 0.05) increase in weight gain (g), percent weight gain (WG%), protein efficiency ratio (PER) and feed efficiency ratio (FER) with increasing dietary lipid level up to 8% and decreased thereafter, but an opposite trend was noted in the feed conversion ratio (FCR). The serum glucose level linearly elevated with the rise in dietary lipid level, but higher lipid (beyond 8%) fed groups showed significantly (p < 0.05) more total protein in serum. Though there was a significant (p < 0.05) difference in cholesterol levels, no clear trend was observed; while other parameters viz., body indices (VSI and HSI), serum albumin, globulin and A-G ratio was not showed any significant (p > 0.05) variation with varying dietary lipid level. Based on regression models, it was observed that the optimum lipid level required for GIFT in ISW (10ppt) is in the range of 8.35-9.05%.