Effect Of Soybean And Raffinose, Stachyose On Growth Performance, Physiological Functions And Intestinal Health Of Allogynogenetic Silver Crucian Carp (Carassius Auratus Gibelio♀×Cyprinus Carpio♂)

An 8-week feeding experiment was conducted to evaluate the effect of 30% soybean meal (SBM) and its oligosaccharides raffinose and stachyose on Juvenile allogynogenetic silver crucian carp (Carassius auratus gibelio♀×Cyprinus carpio♂, initial body weight: 24.7±0.4g). Fish meal (FM) based diet (fish meal and fish oil used as the main protein source and lipid source respectively, CP: 54.74%) used as control and SBM diet contained 300g kg^-1 SBM instead of fish meal. Raffinose and stachyose were added to the FM based diet separately or together at concentration of 6.7 g kg^-1 and 26.1 g kg^-1 respectively (which were according to their content of SBM). In order to reveal the potential effect of saponins on the two oligosaccharides, saponins (1.6 g kg^-1, which was according to its content of SBM) was added to FM when two oligosaccharides had been added. The experiment was conducted in a semi-open and re-circulated system. Water temperature, DO and pH were 23 27℃, above 5.0mg/L and 7.3⁷.8 respectively. All indexes were up to the standard of aquatic water. Each treatment had four replicates. Fish were fed three times daily to apparent satiation. Growth performance, feed utilization, serum biochemical indicators, immunity functions, intestinal morphology and intestinal microflora were analyzed after eight weeks.The results showed: the weight gain ratio and special growth ratio of Allogynogenetic silver crucian carp were 106 130 % and 1.10 1.39 % d-1 respectively; compared with FM group, weight gain ratio and special growth ratio of SBM group decreased 18.5% and 13.7% respectively, differences were significant (P<0.05); raffinose and stachyose had no effect on weight gain ratio and special growth ratio. Compared with FM group, serum total cholesterol (TCHO) and high density lipoprotein cholesterol (HDL-C) of SBM group decreased 28.2 % and 33.3 % respectively, and serum TCHO decreased 16.5 % when raffinose was supplemented alone, all differences were significant (P <0.05), and there were no significant difference among the other groups (P >0.05); compared with FM group, much more lymphocytes infiltrates in intestinal submucosa and mucosal folds stroma was observed. No obvious changes were taken place in the other groups; the activity of transaminase (GPT and GOT) and superoxide dismutase (SOD) in serum and hepatopancreas, lysozyme (LSZ) and SOD in mucus, and brush border enzymes including alkaline phosphatase (AKP) and maltase in intestinal sections were no significant difference among all groups (P>0.05); the intestinal microflora and lymphocyte transformation ratio were no significant difference among all groups (P>0.05); saponins had no obvious effect on all indicators above. These results suggested: when Fish meal was substituted by SBM, the growth of Allogynogenetic silver crucian carp was restricted and the changes of intestine were pathologic. Raffinose and stachyose were not the factors which restrict the ability of Allogynogenetic silver crucian carp utilizing SBM, and the antagonism may exist between the two oligosaccharides. Saponins had no obvious effect on the function of the two oligosaccharides.