Comparative utilization of rendered animal derived products with or without composite mixture of soybean meal in hybrid tilapia (Oreochromis niloticus x Oreochromis mossambicus) diets

The utilization potential of some rendered animal protein derived products as partial replacement for high grade fish meal protein in practical diets for hybrid tilapia was investigated in two successive laboratory feeding trials. In trial 1, rendered animal protein sources, poultry by-product meal (PBM), hydrolyzed feather meal (HFM), enzyme treated feather meal (EFM) and blood meal (PBM) were used to partially replace high grade low temperature Norwegian fish meal (LT-94) at 66% dietary inclusion for juvenile tilapia in an experiment that lasted for 70 days. In trial 2, the effects of hydrolyzed or enzyme treated feather meals with or without composite mixture of soybean meal as partial replacement for low temperature fish meal in diets for hybrid tilapia fingerlings was investigated for 56 days. Trials 1 and 2 comprising five diets in triplicate treatments each were made isonitrogenous at 30% and 35% crude protein while energy levels of diets were isocaloric at 8% and 12% lipid for juveniles and fingerlings of hybrid tilapia, respectively. The results of trial 1 showed that fish fed poultry by-product meal (PBM) had the best productivity values of weight gain, feed conversion ratio, specific growth rate and protein efficiency which were not significantly different (P >= 0.05) from values obtained for fish fed the fish meal based (control) diet. Fish fed the enzyme treated feather meal in both trials 1 and 2 had higher values of growth performance and nutrient utilization than corresponding fish fed the hydrolyzed feather meal. However, composite mixture of hydrolyzed feather meal with soybean meal had considerable improvement on fish growth and nutrient utilization while there was no significant changes in the productivity values of fish fed enzyme feather meal with or without soybean meal dietary inclusion. Fish fed blood meal had the poorest productivity values but similar to fish fed hydrolyzed feather meal in weight gain and protein efficiency. (c) 2005 Elsevier B.V. All rights reserved.