| The juvenile hybrid grouper,Epinephelus lanceolatus♂×E.moara♀,which has the advantages of good growth performance and high resistance.In this research,we studied the effects of different protein and energy content on the juvenile hybrid grouper growth,body composition,protein utilization,intestinal digestive enzyme activity,liver antioxidant capacity and serum biochemical indicators,etc.,and calculate the most suitable protein-energy ratio,in order to provide reference for the production of feed.Abstract 1:In order to investigate the optimal dietary protein and energy levels of a new juvenile hybrid grouper(Epinephelus lanceolatus♂×E.moara♀),nine diets were formulated containing three dietary protein levels(46 %,50 % and 54 % crude protein)and three dietary energy levels(20.00 kJ/g,20.50 kJ/g and 21.00 kJ/g gross energy),the dietary protein-energy ratio was in the range of 22.04 to 26.87 mg/kJ.Juvenile grouper averaging(46.23±0.51)g were fed the test diets for 56 days.The results indicated that the interaction between protein and energy had a significant effect on the weight gain(WG)of grouper(P<0.05),the weight gain rate(WGR)and specific growth rate(SGR)increased with increasing of dietary protein and energy levels(P<0.05).Protein deposition rate(PDR)and hepatosomatic index(HSI)were significantly affected by the interaction between protein and energy(P<0.05).The energy retention rate(ERR)and condition factor(CF)increased with increasing of dietary protein levels(P<0.05),while the protein efficiency ratio(PER)increased first and decreased afterwards(P<0.05).The PER and ERR increased with increasing of dietary energy levels(P<0.05).PDR and PER of D6 group were significantly higher than other groups(P<0.05).The interaction of protein and energy had no significant effects on moisture,crude protein and crude ash of whole fish and muscle(P>0.05).The crude protein of whole fish and muscle increased with increasing of dietary protein levels(P>0.05).Moisture decreased with increasing of dietary energy levels(P<0.05).Crude fat of whole fish increased with decreasing of dietary protein-energy ratio(P<0.05).According to these results,adiet containing 50 % protein and 21.00 kJ/g energy were recommended for efficient growth of juvenile hybrid grouper.Abstract 2:In order to investigate the optimal dietary protein and energy levels of a new juvenile hybrid grouper(Epinephelus lanceolatus♂×E.moara♀),nine diets were formulated containing three dietary protein levels(46 %,50 % and 54 % crude protein)and three dietary energy levels(20.00 kJ/g,20.50 kJ/g and 21.00 kJ/g gross energy),the dietary protein-energy ratio was in the range of 22.04 to 26.87 mg/kJ.Juvenile grouper averaging(46.23±0.51)g were fed the test diets for 56 days.The results indicated that Total antioxidant capacity(T-AOC)and Superoxide dismutas(SOD)were significantly affected by the interaction between protein and energy(P<0.05).Malondialdehyde(MDA)decreased with increasing of dietary protein and energy levels(P<0.05)and T-AOC and SOD increased significantly(P < 0.05).The interaction of protein and energy had no significant effects on serum biochemical indexes(P>0.05).Total protein(TP)increased with increasing of dietary protein levels(P<0.05).Total cholesterol(CHO),High-density lipoprotein cholesterol(HDL-C),Low-density lipoprotein cholesterol(LDL-C)increased with increasing of dietary energy levels(P<0.05).According to these results,a diet containing 50 % protein and 21.00 kJ/g energy were recommended for efficient growth of juvenile hybrid grouper.Abstract 3:In order to investigate the optimal dietary protein and energy levels of a new juvenile hybrid grouper(Epinephelus lanceolatus♂×E.moara♀),nine diets were formulated containing three dietary protein levels(46 %,50 % and 54 % crude protein)and three dietary energy levels(20.00 kJ/g,20.50 kJ/g and 21.00 kJ/g gross energy),the dietary protein-energy ratio was in the range of 22.04 to 26.87 mg/kJ.Juvenile grouper averaging(46.23±0.51)g were fed the test diets for 56 days.The results indicated that the interaction of protein and energy had significant effect on the activities of trypsin,lipase and amylase(P<0.05).The pepsin activity increased with increasing of dietary protein levels(P<0.05),and dietary energy levels had no significant effect on it(P>0.05).The trypsin activity of D6 group was significantly higher than other groups(P<0.05),which increased first and then decreased with decreasing of dietary protein-energy ratio(P<0.05).The lipase activity of fish fed diets containing 21.00 kJ/g energy was significantly higher than other groups(P<0.05).The interaction of protein and energy had a significant effect on the fold height(P <0.05).Fold height of D6 group were significantly higher than other groups(P<0.05).Fold number increased withincreasing of dietary protein and energy levels(P<0.05).According to these results,a diet containing 50 % protein and 21.00 kJ/g energy were recommended for efficient growth of juvenile hybrid grouper. |
