EFFECTS OF FISH MEAL REPLACED BY FERMENTED FEATHER MEAL ON GROWTH, HEALTH STATUS AND NUTRIENT DIGESTIBILITY OF GROUPER Epinephelus coioides

The present study evaluated the effects of fish meal replacement by fermented feather meal on growth, health status and nutrient digestibility of grouper (Epinephelus coioides). Fish meal protein was replaced by Bacillus fermented feather meal at 0, 50, 100, 200 and 300 g/kg in the basal diet. Total of five experimental diets were each fed to triplicate groups of juvenile grouper (initial weight: 3.24 ± 0.03 g) in a closed recirculating system with seawater for 8 weeks. Grouper fed diets with 0-100 g/kg fish meal protein replacement by fermented feather meal had better (P<0.05) weight gain, feed efficiency, protein retention and protein efficiency ratio than fish fed the 200 and 300 g/kg replacement groups. The parameters for health status of grouper, including hematology, plasma lysozyme activity, immunoglobulin concentration and hepatic oxidative status, showed no significant difference among all dietary treatments. Apparent dry matter digestibility was the highest in fish fed 0 and 50 g/kg replacement diets, followed by fish fed 100 and 200 g/kg replacement diets, and the lowest in fish fed the 300 g/kg replacement diet. Fish fed 0and 50 g/kg replacement diets had the highest protein digestibility, followed by fish fed the 100 g/kg replacement diet, then fish fed the 200 g/kg replacement diet, and the lowest in fish fed the 300 g/kg replacement diet. Lipid digestibility was higher in fish fed 0-100 g/kg replacement diets than that in fish fed 200 and 300 g/kg replacement diets. Results indicated that the fermented feather meal can be used to replace fish meal protein up to 100 g/kg without any negative effects on growth and health status for grouper.