Dietary requirement for lysine by juvenile Penaeus vannamei using intact and free amino acid sources

Abstract

In a preliminary experiment, order-of-limitation of lysine, arginine and methionine was determined for wheat gluten fed to juvenile shrimp. Limitation diets were prepared by singular deletion of the crystalline component of one of the above amino acids from a control diet. Shrimp fed deletion diets had significantly less weight gain than those fed the control diet with the order-of-limitation being lysine ≥ methionine ≥ arginine with lysine being significantly more limiting than arginine. In a subsequent experiment, the dietary requirement for lysine was estimated using juvenile Penaeus vannamei and a 21-day experimental period. Shrimp were fed four different types of diets: (1) 35% crude protein, lysine supplementation via covalently lysine-enriched wheat gluten; (2) 35% crude protein, lysine supplementation via l-lysine HCl; (3) 45% crude protein, lysine supplementation via covalently lysine-enriched wheat gluten; and (4) 45% crude protein, lysine supplementation via l-lysine HCl. Diets containing 35% crude protein contained graded levels of lysine ranging from 3.43 to 6.57% of the protein. Lysine in the diets containing 45% crude protein ranged from 3.33 to 6.67% of the dietary protein. Apparent requirement for lysine was estimated by broken-line regression of instantaneous growth coefficient (IGR) against dietary lysine concentration. No significant difference ( P < 0.05) in survival was observed among shrimp fed any of the four different types of diets. Irrespective of means of lysine supplementation, the apparent requirement for lysine by shrimp fed diets containing 45% crude protein was 4.67% of the protein. The apparent requirement for lysine by shrimp fed the diet containing 35% crude protein supplemented with wheat gluten and with l-lysine HCl was 4.49 and 5.19% of the protein, respectively.