Replacement of fishmeal by canola protein concentrate in diets fed to rainbow trout (Oncorhynchus mykiss)

Abstract

A dephytinized protein concentrate prepared from canola seed (CPC) was assessed for nutrient digestibility and performance in rainbow trout (Oncorhynchus mykiss). The apparent digestibility coefficients of CPC were: dry matter, 817 g kg−1; crude protein, 899 g kg−1; gross energy, 861 g kg−1; arginine, 945 g kg−1; lysine, 935 g kg−1; methionine, 954 g kg−1; threonine, 893 g kg−1. A 9-week performance trial assessed 7 diets. Fishmeal provided 940 g kg−1 of the protein in the control diet. Test diets consisted of CPC or water-washed CPC replacing 500 and 750 g kg−1 of fishmeal protein; and CPC plus an attractant replacing 500 and 750 g kg−1 of fishmeal protein. No significant differences in performance were observed (P > 0.05). A subsequent 9-week performance trial evaluated the effect of adding CPC into compound diets containing fishmeal/soybean meal/corn gluten meal. Five diets were prepared: fishmeal provided 670 g kg−1 of the protein in the control diet, in the remaining diets CPC was incorporated into commercial-like trout diets at 100, 200 and 300 g kg−1 replacement of fishmeal protein, the fifth diet included an attractant in the 300 g kg−1 replacement diet. No significant differences in performance were obtained (P > 0.05). These studies show that dephytinized canola protein concentrate has potential to replace substantial levels of fishmeal in diets for carnivorous fish without compromising performance.