Evaluation Of Enzymatic Hydrolyzate From Tilapia Wastes As A Replacement For Fish Meal In Practical Diets Of Juvenile Tilapia

This paper aimed at producing fish protein from tilapia wastes through enzymatic hydrolysis technique. The paper firstly studied different enzymatic hydrolysis conditions of papain, to evaluate the effects of four hydrolyzing factors including temperature, time and amounts of water added and enzyme-substrate ratio on a-Amino Nitrogen contented in tilapia wastes protein hydrolysis. Study showed that in the nature pH, the optimal enzymolysis temperature of55℃, the optimal enzyme addition of700U·g-1, the optimal enzymolysis enzyme-substrate ratio of1:2g·ml-1and the optimal enzymolysis time of6h, respectively, and a degree of hydrolysis up to10.05%was obtained under this condition, and the enzymolysis liquid amino acid nitrogen concentration was1.4mg·ml-1. The test evaluate the possibility of enzymatic hydrolysis as the potential source of protein for fingerling tilapias. Each diet was fed for63days to three replicate groups of20fish (1.69±0.03g; mean±SE), arranged in a completely randomized design by nets in an indoor cement pit with circulation system. Six test diets were formulated to contain enzymatic hydrolysis at levels of3.1%,6.2%,9.3%,12.2%and15.3%of the diets or replaced20%、40%、60%、80%、18.19%and100%of the total dietary protein (Diet1,2,3,4and5) respectively and one diet acting as a control included high quality steam fish meal as protein sources. All diets were isonitrogenous and isoenergetic intake. No mortality was observed during the whole test period. Fish in diets with3.1%enzymatic hydrolysis (Diet1) raised somewhat specific growth rate, feed effectiveness rate and protein effectiveness rate compared to fish in control. The special growth ratio, feed effectiveness rate and protein effectiveness rate did not differ significantly (P>0.05) between fish fed diets and the control diet, but fish fed diet5showed poorer FER and PER than the control group (P<0.05). No significant difference in carcass main chemical compositions, Hepatosomatic index and Intestinalsomatic indices were found among the treatments.(P>0.05).Results showed that enzymatic hydrolysis of tilapia wastes could be replaced fish meal in practical diets of juvenile Tilapia and the adaptable diets is80%.