DIETARY REQUIREMENT FOR LYSINE BY JUVENILE PENAEUS-VANNAMEI USING INTACT AND FREE AMINO-ACID SOURCES

In a preliminary experiment, order-of-limitation of lysine, arginine a nd 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 greater tha n or equal to methionine greater than or equal to arginine with lysine being significantly more limiting than arginine. In a subsequent expe riment, the dietary requirement for lysine was estimated using juvenil e Penaeus vannamei and a 21-day experimental period. Shrimp were fed f our different types of diets: (1) 35% crude protein, lysine supplement ation via covalently lysine-enriched wheat gluten; (2) 35% crude prote in, lysine supplementation via L-lysine HCl; (3) 45% crude protein, ly sine 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. Appar ent requirement for lysine was estimated by broken-line regression of instantaneous growth coefficient (IGR) against dietary lysine concentr ation. No significant difference (P < 0.05) in survival was observed a mong shrimp fed any of the four different types of diets. Irrespective of means of lysine supplementation, the apparent requirement for lysi ne by shrimp fed diets containing 45% crude protein was 4.67% of the p rotein. The apparent requirement for lysine by shrimp fed the diet con taining 35% crude protein supplemented with wheat gluten and with L-ly sine HCl was 4.49 and 5.19% of the protein, respectively.