Evaluation of optimum dietary protein level for juvenile whiteleg shrimp (Litopenaeus vannamei)

Abstract

An 8-week feeding trial was carried out to evaluate the optimum level of dietary protein in juvenile whiteleg shrimp, Litopenaeus vannamei (Boone, 1931). Five experimental diets, containing 25, 30, 35, 40 and 45% crude protein (CP) (CP25, CP30, CP35, CP40 and CP45, respectively) were fed shrimp for 8 weeks. Triplicate of 55 shrimp averaging |$1.3\pm\ 0.09\ {\rm g}\ (\hbox{mean}\ \pm\ {\rm SD})$| were randomly distributed into each of five diets in 15 circular fiberglass tanks of 200 l capacity. The growth performance was enhanced |$(P \lt 0.05)$| linearly and quadratically in shrimp fed diets containing different protein level. Protein efficiency ratio was significantly affected by dietary protein level. Average plasma total protein and cholesterol values were significantly increased among all treatments. Also dietary protein levels significantly influenced on whole body proximate and amino acid composition, and average waste nitrogen excretion parameters such as ammonia nitrogen (TAN), nitrogen as nitrite |$({{\rm NO}_2}^-\hbox{-}\!\hbox{-}{\rm N})$| and nitrogen as nitrate |$({{\rm NO}_3}^-\hbox{-}\!\hbox{-}{\rm N})$|⁠. Broken-line analysis of WG indicated that the optimum dietary protein level could be 33.4% for maximum growth performance and the dietary protein requirement could be greater than 25% but less than or equal to 33.4% in juvenile whiteleg shrimp.