Effects Of Tea Polyphenols On Growth、Immunity And Lipid Metabolism In Juvenile Mylopharyngodon Piceus

An8-week feeding experiment was conducted to evaluate the effect of dietary Tea Polyphenols on growth, immunity and lipid metabolism in juvenile black carp [initial average weight of (5.90±0.03) g]. The inclusion levels of TP were0(control),25mg/kg,50mg/kg,100mg/kg,500mg/kg. Each diet was randomly fed to triplicate groups of30fishes per tank (300L).The results indicated that:1. GrowthThe diets with tea polyphenols had no significant differences on the survival of Mylopharyngodon piceus, When the inclusion level was50mg/kg, the diet could increase significantly the specific growth rate and relative fatness (%)(P<0.05), But adding excessive level will show certain inhibitory influence on the growth. In the aspect of digestive enzymes,no significant differences in Amylase, the activity of intestinal protease and lipase was significantly higher than the control at the group which fed with50mg/kg (P<0.05), but when the inclusion level was500mg/kg,the activity of intestinal protease and lipase of Mylopharyngodon piceus was significantly inhibited (P<0.05). In terms of body composition, all the tests had no significant differences on the Ash of Mylopharyngodon piceus,but the crud lipid of Mylopharyngodon piceus was decreased at first and then increased as the content of TP in diets were increased, and the crud protein was significantly lower than the control at the group which fed with500mg/kg (P＜0.05)2. Non-specific immunityThe diets with tea polyphenols had no significant differences on the activity of T-AOC and ASAFR, and could significantly increase the activity of SOD in serum of Mylopharyngodon piceus. Compared with the control, all tests could significantly reduce the content of GSH, GSH-Px and MDA (P＜0.05). When the diet with excessive levels TP could make the body to produce certain stress reaction and increase the content of GLU and Cortisol in serum,and could have negative effects on the complement system, when the concentration of500mg/kg, the activity of C3and C4was significantly lower than the control group (P<0.05). The content of LSZ was increased at first and then decreased as the level of TP in diets, andthe LSZ of the group with50mg/kg was significantly higher than the control group (P＜0.05). But the content of IgM showed increasing at first and then reducing as the lever of TP.3. Lipid metabolismThe diets with tea polyphenols could significantly decrease the content of TG and LDL-C. When the diet with500mg/kg, the content of HDL-C in serum was significantly lower than the control group (P<0.05). In the aspect of transaminase, the activity of GPT and GOT in serum was significantly higher than the control at the500mg/kg group (P＜0.05)Compared with the control, all tests had no significant differences on the content of GH in serum of Mylopharyngodon piceus, but the content of IGF-1was reduced at first and then increased as the content of TP in diets.The expression level of A-1gene of all experimental groups were lower than the control, and showed reducing as the lever of TP. The diets with tea polyphenols had differences on the expression level of MC4R and GH gene in different tissue. The expression level of MC4R and GH gene was increased at first and then decreased as the content of TP, when the diet with50mg/kg, the expression level of MC4R and GH was the highest.