Evaluating dietary impacts of commercial-type diets on the growth of Snake River cutthroat trout (Oncorhynchus clarkii behnkei)

A six-month feeding trial was conducted to evaluate the effects of feed formulation on growth performance and proximate composition of Snake River cutthroat trout (Oncorhynchus clarkii behnkei) (initial body weight: 8.6 ± 2.0 g). Two commercially available control diets and four experimental diets formulated with varying levels of crude protein (CP) and crude lipid (CL) were used (40CP:12CL, 45CP:16CL, 45CP:24CL, 40CP:20CL amino acid supplemented [BFTC Experimental]). The results showed that fish fed diets with > 40% crude protein and 12% crude lipid had the highest final body weights, final body lengths, specific growth rates, weight gains and the lowest feed conversion ratios. Energy content was significantly higher in fish fed the 45CP:24CL diet than fish fed the 40CP:12CL or its corresponding control diet. Rudimentary cost analyses suggest that diets with higher nutrient density and amino acid supplementation have lower costs per kg gain than trout grower diets.