Dietary lipid requirement of juvenile white‐leg shrimp, Penaeus vannamei (Boone, 1931) reared in inland ground saline water of 15 ppt.

Abstract

A 60- day feeding trial was conducted to evaluate the optimum dietary lipid level in terms of growth performance, digestive enzymes and hemato- biochemical pa-rameters of white- leg shrimp, Penaeus vannamei juveniles in inland ground sa-line water (IGSW) of 15 ppt salinity. The shrimps (avg. wt., 4.04 ± 0.03 g) were randomly distributed in six groups in triplicates (15 shrimps/tank, 290 L), viz., TCL40 (40 g/kg lipid), TCL60 (60 g/kg lipid), TCL80 (80 g/kg lipid), TCL100 (100 g/kg lipid), TCL120 (120 g/kg lipid) and TCL140 (140 g/kg lipid). Six semi- purified hetero- lipidic (40-140 g lipid/kg), hetero-caloric (376–426 Kcal DE/100 g) and iso- nitrogenous (400 g crude protein/kg) diets were prepared and fed to respec-tive groups four times daily. Weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) showed higher quad-ratic relations (R2= 0.97, 0.98, 0.94 and 0.87, respectively) to dietary lipid levels (p< 0.05) with enhancing dietary lipid up to 60 g/kg. Whole body moisture and lipid contents exhibited a high linear (R2= 0.87 and 0.98) and quadratic (R2= 0.88 and 0.98) (p< 0.05) inverse relationship with enhancing dietary lipid levels up to 140 g/kg. Hemolymph hemocyanin, serum total protein and glucose level did not differ significantly (p> 0.05), but the TCL60 group showed significantly (p< 0.05) higher serum cholesterol and triglyceride levels. Serum osmolality, osmoregula-tory capacity, and branchial Na+/K+- ATPase activity was similar (p> 0.05) among the groups. Hepatopancreatic lipase and amylase activity significantly (p< 0.05) increased, but trypsin activity did not vary significantly (p> 0.05) among the groups. Second-degree polynomial analysis with WG, SGR and FCR indicated that a 55.80–58.80 g lipid/kg diet is optimum for P. vannamei juveniles in IGSW of 15 ppt salinity.