Influence of dietary soy and phytase levels on performance and body composition of large rainbow trout (Oncorhynchus mykiss) and algal availability of phosphorus load.

Rainbow trout were fed experimental diets to evaluate the partial replacement of fish meal with soybean meal and the effects of supplemental phytase on phosphorus utilization. The experiment was a 2 x 2 factorial design with 0 and 60.4 percent of the dietary protein from soy protein concentrate and 0 and 1200 units of phytase added per kg diet. The diets were formulated to contain 36 percent protein and supplemented with lysine and methionine. The phosphorus levels of the diets containing fish meal were higher than those containing soy protein (10.5g/kg and 6.5g/kg, respectively). Results indicate that soy protein can replace fish meal in practical rainbow trout diets without reducing weight gains or feed efficiencies. Bone ash was significantly lower in the soy protein fed fish. The phytase addition did not influence fish weight gains or increase bone ash of the fish fed the soy diets.

Vielma, J. and co-workers. 2000. Influence of dietary soy and phytase levels on performance and body composition of large rainbow trout (Oncorhynchus mykiss) and algal availability of phosphorus load. Aquaculture 183(3-4):349-362,