Effects of fish meal replacement and selective breeding on Rainbow Trout performance characteristics

The highest priority challenge for increasing aquaculture production in a sustainable manner is to reduce dependence on fish meal and fish oil. This is a complex issue and only a basic understanding exists of the biochemical or molecular value of feeding fish meal and fish oil or in feeding alternative ingredients to fish. To increase the understanding of the effects of replacing fish meal in aquafeeds for rainbow trout, two experiments were performed that correlated physiological growth measurements to plasma parameters, white muscle enzyme activities and expression of genes in white muscle that have roles in muscle development and growth.;A nine-week feeding study was conducted comparing three plant protein diets devoid of or supplemented with carnosine to a fish meal control diet. Carnosine functions as a muscle antioxidant, but has no defined physiological effect. Feeding diets without fish meal resulted in reduced muscle ratio (MR), increased intraperitoneal fat ratio (IPFR) and increased calpain induced proteolysis. Carnosine did not significantly improve the 100% plant protein diets in regard to the measured growth characteristics above the amino acid supplemented plant protein diets and other unidentified factors may be limiting in the diet causing the reductions in MR and elevated IPFR.;A twelve-week feeding study was conducted to determine differences in rainbow trout growth through two generations of selection for increased weight gain utilizing a plant-based feed to provide selection pressure. Fish fed a fish meal control diet exhibited faster growth, lower feed consumption and lower feed conversion ratio (FCR) compared to fish fed the plant meal diet. The increased weight gain after two generations of selection correlated with muscle expression of the IGF-1, Foxo-1 and Pax-7 genes.