Effects of graded dietary lipid levels on growth, feed utilization, body composition and metabolism in juvenile white leg shrimp, Penaeus vannamei (Boone, 1931) reared in inland saline water of 10 g/L salinity.

Abstract

A feeding trial was performed for 60 days to determine the dietary lipid requirement of Penaeus vannamei juveniles reared in inland saline water (ISW) of 10 g/L salinity. Six iso- nitrogenous (360 g/kg crude protein) and heterocaloric (15.4–17.6 KJ DE/g) semi- purified diets were prepared with graded level of lipid viz., 20, 40, 60, 80, 100 and 120 g/kg (L2–L12 with 20 g/kg incremental level). Two hundred and seventy P. va n-namei juveniles (5.51 ± 0.01 g) were randomly allocated (15 shrimps/200 L) into six treatment groups in triplicate following a completely randomized design. The shrimp of L4 and L6 groups exhibited significantly higher per cent weight gain (WG%), spe-cific growth rate and protein efficiency ratio and the lowest feed conversion ratio. The lipid efficiency ratio and hepatopancreatic somatic index were significantly de-creased and increased with increasing levels of lipid respectively. The L6, L8 and L10 groups exhibited significantly higher (p< .05) lipase activity. Shrimp of higher dietary lipid fed groups exhibited significantly higher (p< .05) aminotransferase activity than their lower dietary lipid fed counterparts. Based on WG% data, broken- line linear and second-order polynomial regression analysis showed that the optimal dietary lipid re-quirement of P. vannamei in ISW of 10 g/L salinity was 46.5 and 51.4 g/kg respectively.