STUDIES ON LYSINE REQUIREMENTS OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) FED WHEAT GLUTEN AS ONLY SOURCE OF DIETARY-PROTEIN

Three feeding trials were performed on rainbow trout. In the first trial, the depression of performance caused by replacing dietary fish meal by wheat gluten plus fish oil was almost eliminated by supplementation of L-lysine . HCl. In the second trial, 8 levels of lysine supplementation were compared. Maximum intake and growth were recorded when diets contained more than 1.0 g lysine per MJ digestible energy, maximum utilization of lysine (74%) was achieved at 0.89 g lysine per MJ DE. In trial 3, it was found that increasing lysine content from 1.3 to 1.6 g/MJ DE lowered feed intake and growth without affecting feed conversion ratios. Supplementing arginine and/or threonine at either level of lysine did not affect intake, growth or composition of gain.