| Abstract: | A preliminary experiment to determine order of limitation of essential amino acids (EAAs) for shrimp fed wheat gluten indicated that lysine was first-limiting, followed by methionine and arginine. A 6.9-fold carbodiimide-mediated enrichment of wheat gluten with minimal isopeptide bonding was possible using L-lysine HCl. Enrichment also resulted in minimal isopeptide bonding of lysine. Apparent digestibility trials showed that diets containing 94% lysine-enriched gluten and 94% unaltered wheat gluten were equally digestible in terms of apparent dry matter digestibility (ADMD), apparent protein digestibilty (APD) and apparent lysine availability (AA-LYS) by both small (11 g) and large (35 g) shrimp. Juvenile shrimp fed an intact amino acid diet and one supplemented with L-lysine HC1 had similar total free essential amino acids (TFEAAs) and individual free essential amino acids (FEAAs) in whole-body and tail muscle tissues at 4 h post-feeding. Shrimp fed a diet containing only crystalline amino acids (CAAs) achieved maximum levels of tissue TFEAAs and individual FEAAs earlier, at 1 - 2 h post-feeding. Change in tissue TFEAAs and individual FEAAs of shrimp fed diets deficient in EAAs was less than that of shrimp fed diets complete in EAAs and more pronounced in shrimp fed a diet deficient in lysine than in arginine. Shrimp were fed diets containing 35 or 45% crude protein in which graded levels of lysine were achieved by varying content of lysine-enriched wheat gluten or L-lysine HCl. The apparent lysine requirement of juvenile shrimp was typically estimated at 4.5 - 4.7% of dietary protein. Shrimp fed diets containing either 45% crude protein or a majority of intact amino acids had greater IGR (intantaneous growth rate) values. Requirements for EAAs by shrimp of different ages and from different culture environments were estimated using A/E ratios. A general increase and decrease in estimated apparent requirements for EAAs was shown with age of shrimp when calculations were based on levels of whole-body tissue and tail muscle tissue EAAs, respectively. Shrimp grown in various environments had the following order of overall requirement values for EAAs: earthen ponds > concrete ponds > indoor tank. |
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