Effects of nutritional conditioning during first feeding and selective breeding with a low fish meal diet on the growth performance of juvenile rainbow trout Oncorhynchus mykiss

Abstract

We investigated the effects of different nutritional condition in early life stage and selective breeding with a low fish meal diet on growth performance of rainbow trout Oncorhynchus mykiss juveniles. Individuals from a non-selected line (Cont) and an F2 generation obtained by selective breeding with a low fish meal content diet (LFMD) (Select) were exposed to different diets (either a fish meal diet (FMD) or LFMD), during first feeding for three weeks. After reaching a body weight of approximately 9 g, the juveniles were subjected to a feeding trial with LFMD for ten weeks. The Select groups showed higher growth rates in the LFMD-feeding trial than the Cont group. There were no significant differences in growth performance of individuals from the Select line, regardless of early nutritional history. In contrast, the juveniles from the Cont line fed LFMD during first feeding showed a significantly lower growth rate than those fed FMD. These results suggest that the growth delay observed in juvenile rainbow trout fed LFMD is caused by the experience of LFMD-feeding in early life stages while the utilization of LFMD is improved by the selective breeding.