Effects of betaine supplementation in plant protein based diets on feed intake and growth performance in rainbow trout (Oncorhynchus mykiss)

The effects of betaine supplementation on feed intake and growth performance in rainbow trout fed a plant-protein based diet were evaluated. Triplicate groups of rainbow trout (130 g) were fed the plant-protein basal diet, the basal diet with 1.5% betaine supplementation, or a fishmeal-based diet (control) for 80 days. Feed intake was significantly better (p<0.05) in fish fed the betaine-supplemented diet (161.2 g/fish) than in fish fed the basal diet (131.6 g/fish) and not significantly different from fish fed the control (152.8 g/fish). Weight gain was significantly higher (p<0.05) in fish fed the betaine-supplemented diet (117.0%) than in fish fed the basal diet (95.9%). Results indicate that, in diets based on plant proteins that often have low palatability, betaine supplementation may improve feed acceptability and growth performance in rainbow trout.