title: Dietary sulfur amino acid requirement of juvenile yellow perch fed the maximum cystine replacement value for methionine.
abstract: We conducted three separate experiments designed to determine the dietary methionine requirement, ability of cyst(e)ine to spare methionine, and the total sulfur amino acid requirement (TSAA) of juvenile yellow perch when fed the maximal amount of cyst(e)ine. The purified basal diet used in each experiment contained 33.6 g of crude protein/100 g diet and 12.0 g of lipid/100 g diet. In the first experiment,;>L-methionine was added to eight diets providing methionine concentrations ranging from 0.37 to 1.77 g/100 g diet in gradations of 0.2 g/100 g diet. Diets were fed for 12 wk to juvenile yellow perch initially weighing 4.7 g/fish. Broken-line analyses of weight gain and feed efficiency data indicated that the dietary methionine requirement was 1.0 g/100 g diet (3.1 g TSAA/100 g dietary protein) and 1.1 g/100 g diet (3.4 g TSAA/100 g dietary protein), respectively. In the second experiment, various ratios of L-cyst(e)ine and L-methionine were added to the basal diet and fed for 12 wk to determine the cyst(e)ine replacement value of yellow perch initially weighing 19.3 g/fish. Weight gain and feed efficiency (FE) data indicated that cyst(e)ine spared up to 51% of the methionine requirement. In the final experiment, graded levels of cyst(e)ine plus methionine in a ratio of 51:49 were added to the basal diet in gradations of 0.1 g/100 g diet (0.5 to 1.2 g TSAA/100 g diet) to determine the dietary total sulfur amino acid requirement. Diets were fed to satiation for 10 wk to fish initially weighing 8. 1 g. Broken-line analyses of weight gain, feed intake and FE data indicated that the dietary TSAA requirement was 0.85, 0.87 and 1.0 g of TSAA/100 g diet (2.5 to 3.0 g of TSAA/100 g of dietary protein), respectively. The majority of dietary TSAA requirements of fish are in the range of 2 to 4 g/100 g of dietary protein and are generally similar to those of both birds and swine, but lower than estimates for rodents.
authors.affiliation: Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN 47907-1159, USA.
authors.forename: R G
authors.initials: RG
authors.lastname: Twibell
authors.forename: K A
authors.initials: KA
authors.lastname: Wilson
authors.forename: P B
authors.initials: PB
authors.lastname: Brown
mesh_terms: D000603:Amino Acids, Sulfur / Q000008:administration & dosage* / Q000494:pharmacology; D000818:Animals; D004032:Diet; D004435:Eating / Q000187:drug effects; D005260:Female; D008715:Methionine / Q000097:blood / Q000378:metabolism*; D009751:Nutritional Requirements; D010471:Perches; D015430:Weight Gain / Q000187:drug effects
chemical_list: D000603:Amino Acids, Sulfur; D008715:Methionine