Effect of Different Protein Sources on Growth Performance, Energy Budget and Hematology Index of Juvenile Epinephelus Fuscoguttatus
|School||Guangdong Ocean University|
|Keywords||Epinephelus fuscoguttatus Nitrogen stable isotopes Muscle composition Energy budget Index of hematology|
Five experimental isoenergetic and isonitrogenous diets at protein levels 50%were formulated with either fish meal protein isolate as the only protein source, or soybean meal (SBM) and fish meal protein (FM) in ratios of 10:90 and 20:80, or corn gluten protein (CGP) and fish meal protein in ratios of 10:90, or beer yeast meal (BYM) and fish meal protein based on nitrogen content. Two sets of experiments were addressed Assessment of the suitability of new Aquacultureulture feed ingredients, one was aimed to compare analysis on the growth, energy budget and hematology of juvenile Epinephelus fuscoguttatus fed with five different protein diets. And the other one was to investigate the utilization potential of components in their compound diets for growth of juvenile Ep. fuscoguttatus.The results can be briefly summarized as follows:1. The 1st trail was conducted to study the effects of five different protein diets on growth performance, body composition, energy budget and index of hematology of juveniles Ep. fuscoguttatus. Fish with initial body weights (18.1±4.2g ww) were divided into 5 groups with 3 replicates of 10 fish in each replicate. This experiment lasted for 56 days. The result showed that: There were no significant difference in survival, BUN, UA, TBIL, the activity of ALT and AST among five groups. PER, SGR and WGR were highest for 10% SBM diet , and then were the 100% FM diet and 10% BYM diet, and that of 10% CGP diet was the lowest. On the contrary, FCR and FR were higher for 10% corn gluten protein group, then 100% FM diet and 10% 10% BYM diet, the lowest was 10% SBM diet, The proportion of energy intake allocated to each channel showed significant differences and could be expressed as follows: 10% SBM diet 100.00C = 21.83G + 19.76F + 6.63U + 51.77R 20% SBM diet 100.00C = 20.37G + 18.06F + 6.04U+ 55.54R 10% BYM diet 100.00C = 18.30G + 20.66F + 7.18U + 53.85R 10% CGP diet 100.00C = 18.20G + 22.09F + 5.64U + 54.08R 100% FM diet 100.00C = 21.43G + 18.86F + 5.84U + 53.86R2. In the 2sec trail, juveniles Ep. fuscoguttatus (22.5±3.2g ww) were fed to satiation twice daily by five diets. Contrasting nitrogen isotopic values (δ15N) of the fish meal and three planted protein allowed estimation of the relative contribution of both ingredients to muscle tissue growth using an isotopic mixing model. The dietary effects on nitrogen turnover rates and on the isotopic diet-consumer discrimination factors (Δ15N) were also assessed. Nitrogen half lives in muscle tissue were estimated from turnover rates and growth after using an exponential model of isotopic change. The result showed that :in all cases, analysis of juvenile muscle tissue indicated a biased nutritional contribution from FM, so that in Ep. fuscoguttatus juveniles fed the mixed diet containing a 10:90 ratio of soybean protein and fish meal protein, 9% of nitrogen in muscle tissue originated from soybean protein; while in juveniles fed mixed diet containing the 20:80 ratio of the two ingredients, the relative contributions of nitrogen from fish meal and soy protein were 87 and 13% respectively. When in juvenile fed the mixed diet containing a 10:90 ratio of corn gluten protein and fish meal protein, incorporated 92% of nitrogen form fish meal and 8% from corn gluten protein. In juvenile fed the mixed diet containing a 10:90 ratio of beer yeast meal and fish meal protein, incorporated 94% of nitrogen form fish meal and 6% from corn gluten protein.The results demonstrated the potential for application of natural stable isotope analysis of diets and tissue in evaluation of plant-source ingredients and the optimisation of their use in diets containing very low levels of fish meal. ANOVA analysis indicated that muscle-diet nitrogen isotope discrimination factors (Δ15N) in juvenile fish were statistically different when final values from the different dietary treatments were compared. And no significant difference in survival and final body weight among five groups. After the 56d rearing period, juvenile fish fed the different diets had increased their mean increase weight Rate by between 164 and 191%.The different dietary treatments had contrasting isotopic influences on muscle tissue. In general, it took 28d forδ15N values in juvenile muscle tissue to reach isotopic equilibrium with their respective diets that fed 10:90 and 20:80 ratio of soybean protein and fish meal protein, and the other three groups need 42d to reach equilibrium.