Utilization of Methionine Supplemented to Diet in Rainbow Trout.

Abstract

To clarify the utilization of dietary methionine in rainbow trout (Oncorhynchus mykiss ), a feeding experiment was conducted. Five experimental diets were prepared: Diet 1, a basal diet containing 50% casein as a sole protein source; Diets 2 to 4, L-methionine was supplemented at levels of 0.5, 1.0, and 1.5% to the basal diet, respectively; Diet 5, containing 50% egg white albumin as a protein source. The fish fed on the methionine-supplemented diet accumulated large amounts of methionine in both the liver and muscle. Unlike methionine contents, hepatic taurine contents were slightly affected by the dietary treatments. Net protein utilization (NPU) was improved by supplementation of methionine up to 1.0%. However, NPU of fish fed on the diet supplemented with 1.5% methionine was lower than that of the 1.0% methionine diet.