Replacing fish meal in rainbow trout (Oncorhynchus mykiss) diets

The effects of Ohio State University (OSU) meal (a mixture of blood meal, meat and bone meal, poultry by-products and feather meal), as partial or total replacement of fish meal was investigated. Thirty-two fish tanks, each containing 30 rainbow trout (initial mean weight 1.93 g), were fed one of 10 diets (the control had only two replicates) containing a different quantity of OSU meal for 14 weeks. The trout fed the diets containing 20% or 40% OSU meal grew similarly to the trout fed the fish meal based diet. Total replacement of the fish meal caused a significant reduction in growth (p<0.05) only at the 47% protein level and not at the 36%. The results of this study suggest that diets containing up to 75% OSU meal and 25% fish meal are sufficient for good growth in rainbow trout fry.