Methionine requirement of juvenile Japanese flounder Paralichthys olivaceus estimated by the oxidation of radioactive methionine. Academic Article uri icon

Abstract

  • Growth and amino acid oxidation studies were conducted to estimate methionine requirement of juvenile Japanese flounder, Paralichthys olivaceus, by using the purifed diets containing 500 g kg±1 crude protein from casein, gelatine and crystalline amino acids (CAA). Diets with six graded levels of methionine (5.3, 8.3, 11.3, 14.3, 17.3 and 20.3 g kg±1 diet) were fed to triplicate groups of the juvenile (initial weight 2.8 ‹ 0.05 g) twice a day for 40 days. To prevent leaching losses, CAA were precoated using carboxymethylcellulose (CMC), and further diets were bound by CMC and j-carrageenan. Based on broken-line analysis of percentage weight gain and feed conversion effciency, the methionine requirements of Japanese flounder in the presence of 0.6 g kg±1 of cystine were 14.9 and 14.4 g kg±1 dry diet, respectively. After the growth study was finished, a direct estimate of methionine requirement was made by examining the influence of dietary methionine level on 14C-methionine oxidation by determin- ing radioactive carbon dioxide, protein and nonprotein fractions of the whole body. The dose±response curve between expired radioactive CO2 and dietary methionine levels showed that the optimum methionine level for the flounder was estimated to be within the range of 14.3±17.3 g kg±1 of diet in high agreement with values obtained from the growth study.

Publication Date

  • 2001-01-01