Use of organically certified yeast in the diet of juvenile rainbow trout (Oncorhynchus mykiss): Growth performance, Nutrient utilization, And fatty acid composition

Abstract

This study evaluated the effects of the dietary organically-certified yeast, NuPro™, used as a replacement for fishmeal, on growth performance, nutrient utilization, and fatty acid composition in juvenile rainbow trout, Oncorhynchus mykiss. Two reference diets (conventional and organic) and three experimental diets (including 10%, 20%, or 30% NuPro™) were formulated. Diets were assigned to triplicate groups of 20 fish (4.0 g) for 12 weeks. There were no differences in growth performance or feed conversion ratio (FCR) between the two reference groups and growth responses were similar among experimental groups (p>0.05). Fish fed the 20% diet grew significantly better than the conventional group (p<0.05). Similarly, there were no significant differences in nutrient utilization between reference groups or between experimental groups, and none in body composition between any group (p>0.05). The highest n-3/n-6 ratio was obtained in fish fed the organic diet and the lowest in fish fed the 30% diet. Results show that organically certified yeast can contribute be an effective alternative to plant proteins in organic trout feed.