Dietary protein requirement of white shrimp, Penaeus vannamei (Boone, 1931) juveniles, reared in inland ground water of medium salinity

Abstract

A 60-day feeding trial was conducted to evaluate the effect of dietary protein level on growth, digestive enzymes and haemato-biochemical responses of Penaeus vannamei juveniles in inland ground saline water (IGSW) of 15 ppt salinity. The acclimated shrimp (avge. wt., 4.03 ± 0.05 g) were randomly distributed into seven groups, viz. TCP20, TCP25, TCP30, TCP35, TCP40, TCP45 and TCP50, in triplicate with the stocking density of 15 shrimp per tank (275 L). Seven semi-purified hetero-nitrogenous (200–500 g crude protein/kg), iso-caloric (396 Kcal DE/100 g) and iso-lipidic (60 g/kg) diets were prepared for feeding the shrimp of respective group four times daily on satiation basis. Results indicated that the highest (p < 0.05) WG and SGR, and the lowest FCR were observed in TCP40 group. But PER and ANPU values decreased significantly (p < 0.05) with increasing dietary protein. Whole-body protein and ash contents varied significantly (p < 0.05) with an inverse relationship. Shrimps of TCP40 group had the highest (p < 0.05) haemocyanin and serum total protein, while TCP20 group showed the highest (p < 0.05) serum glucose. Serum cholesterol and triglyceride increased significantly (p < 0.05) with increasing dietary protein level up to 400 g protein/kg and beyond that these decreased gradually. Protease activity increased with increasing dietary protein level, but amylase activity showed an inverse trend. Second-order polynomial regression analysis in relation to WG, SGR and FCR indicated that 393.0–397.90 g protein/kg diet could be optimum for culture of P. vannamei juveniles in IGSW of 15 ppt salinity.