Ingredients (g per Kg), proximate composition on a dry weight basis (%) and δ15N values of four experimental diets containing different levels of substitution of fishmeal with poultry by-products meal (PBM; 0, 33, 67 and 100% replacement).

The four diets were fed to juvenile rainbow trout (Oncorhynchus mykiss) for 80 d. Fractional N contribution is expressed inside parentheses ( ).1“Pet food grade” (69.6% crude protein, 12% crude lipid) supplied by the National Renderers Association, USA.2Tuna fishmeal (60.0% crude protein, 6.9% crude lipid) from Proteínas Marinas y Agropecuarias, Guadalajara, México.3Poultry oil from Proteínas Marinas y Agropecuarias, Guadalajara, México.4Sardine oil.5Rovimix; Stay–C donated by DSM, Guadalajara, México.6Nitrogen free extract: calculated by difference: NFE = 100-CP-CF-Ash.δ15N values of main nitrogen-containing ingredients: Fishmeal (14.1‰), poultry by-product meal (3.4‰) and gelatin (7.8‰).Ingredients (g per Kg), proximate composition on a dry weight basis (%) and δ15N values of four experimental diets containing different levels of substitution of fishmeal with poultry by-products meal (PBM; 0, 33, 67 and 100% replacement).