Effects of Fishmeal Substituted by Various Plant Proteins Supplemented with Crystalline Amino Acids on Growth and Immunology Performance of Hemibarbus maculatu Juveniles

A feeding trial was conducted to evaluate the maximum level of substitution of dietary fish meal by various proportions of corn protein meal, cottonseed meal and soybean meal supplemented with crystalline lysine, methinoine and arginine according to amino acid profile for fish meal for Hemibarbus maculatu juveniles weighing 14.84 g. The fish were stocked into 15 net cages of each 60 cm×60 cm×120 cm placed in a flowing tank and fed with 5 diets containing 37.0% crude protein with the same amino acid profile but with 28.0%(F0,control),21.0%(F1), 14.0%(F2), 7.0%(F3)and 0%(F4)levels of fish meal at water temperature of 25.0±3.0℃ for breeding 100 days. The results showed that there were no significant differences (P0.05) in survival rate in the fish fed with different levels of fish meal. The fish fed with the diet containing 21.0% fish meal supplemented with the amino acids had significantly higher growth, immunity and digestive enzymatic activities than the fish fed with the diets containing 28.0% fish meal(control group) (P0.05). However, the fish fed with the diet containing 14.0% and 7.0% fish meal supplemented with the amino acids had the same growth, immunity and digestive enzymatic activities as the fish fed with the diets containing 28.0% fish meal (control group) (P 0.05). There was significantly lower growth, immunity and digestive enzymatic activities in the fish fed the diets containing 0% fish meal than in the fish fed the diets containing 14.0% and 7.0% fish meal (P0.05). Our experiment results suggested that plant feedstuffs supplemented with crystalline amino acids could replace dietary fish meal in Hemibarbus maculatu juveniles by 18.69%. The muscular moisture and ash levels were not significantly affected by the substitution of dietary fish meal by various plant proteins (P 0.05), but the muscular protein, total amino acid, essential amino acid and fat levels were higher in the fish fed with the diets containing various plant proteins supplemented with crystalline amino acids than in the fish fed with the control diets.