Effects Of Dietary Mulberry Leaf Flavonoids On Growth,antioxidant Activity And Intestinal Health Of Litopenaeaus Vannamei

The purpose of this thesis was to research the effects of mulberry leaf flavonoids on growth performance,muscle and body composition,serum biochemical parameters,serum and hepatopancreas antioxidant indices,intestinal mucosa structure and gut flora of Litopenaeaus vannamei.The research content includes:(1)Effects of dietary mulberry leaf flavonoids on growth performance,serum biochemical parameters,antioxidant indices and anti-hypoxic stress ability of Litopenaeaus vannamei;(2)Effects of mulberry leaf flavonoids on intestinal mucosa structure and gut flora of Litopenaeaus vannamei.The main results are as follows:1.Effects of dietary mulberry leaf flavonoids on growth performance,serum biochemical parameters,antioxidant indices and anti-hypoxic stress ability of Litopenaeaus vannameiA total of 960 Litopenaeaus vannamei with an initial body weight of(1.32 � 0.01)g were divided into 6 groups with 4 replicates in each group and 40 shrimp in each replicate.Four diets were formulated to contain 0,10,50,100,150 and 300 mg/kg diet of mulberry leaf flavonoids.The trial lasted for 50 days.Results indicated that there was no significant difference in survival rate(SR),weight gain(WGR),Specific growth rate(SGR)and feed conversion ratio(FCR)among the groups(P>0.05),and the WGR was the highest at 50 mg/kg group,6.76% higher than the control group;there was no significant effect on the muscle and whole body composition(P>0.05),Adding 100 mg/kg of mulberry leaf flavonoids in the diet significantly increased sum of essential amino acids,leucine,serine and aspartic acid contents(P<0.05).Compared with the control group,the ratio of essential amino acids to total amino acids in the 10mg/kg group,50 mg/kg group,100 mg/kg group and 150 mg/kg group increased by1.53%,5.95%,1.08% and 0.29%,respectively.The sum of flavor amino acids showed no significantly different(P<0.05).Adding 150 mg/kg and 300 mg/kg of mulberry leaf flavonoids in the diet significantly increased the activity of AST and ALT in serum of Litopenaeaus vannamei(P<0.05).The total antioxidant capacity(T-AOC)in serumand liver were significantly increased by adding mulberry leaf flavonoids to diet,and the content of malondialdehyde(MDA)and lipid peroxide(LOP)in liver were significantly decreased adding 50 mg/kg mulberry leaf flavonoids significiantly increased the activity of glutathione peroxidase(GSH-Px)in serum(P<0.05);5)At 2 h of hypoxic stress,the cumulative mortality of the 10 and 50 mg/kg groups was significantly lower than that of the control group,and at 4 h,the cumulative mortality of the 10,50 and 100 mg/kg groups was significantly lower than that of the control group(P<0.05).In conclusion,The ratio of essential amino acids to total amino acids in the muscle of Litopenaeaus vannamei was increased by 5.95% by adding 50 mg/kg of mulberry leaf flavonoids to the diet,using the T-AOC of the serum as the evaluation index,by analysis of regression equation showed that the optimal supplemental level of mulberry leaf flavonoids in the diet of Litopenaeaus vannamei was 56.18 mg/kg,and adding 10-100mg/kg mulberry leaf flavonoids could improve anti-hypoxic stress ability of Litopenaeaus vannamei.2.Effects of mulberry leaf flavonoids on intestinal mucosa structure and gut flora of Litopenaeaus vannameiThe effects of mulberry leaf flavonoids on intestinal mucosal structure and gut flora of Litopenaeus vannamei were evaluated in this study.(Method)A total of 800 shrimp with an initial body weight of(1.32 � 0.01)g were divided into 5 groups with 4replicates in each group and 40 shrimp in each replicate.Four diets were formulated to contain 0,50,100,150 and 300 mg/kg diet of mulberry leaf flavonoids.The trial lasted for 50 days.Results indicated that dietary mulberry leaf flavonoids improved the villus in the middle intestine of shrimp by increasing the thickness of muscle layer.The height of villus in the 100 mg/kg group was higher than other groups(P<0.05)and the thickness of muscle layer in 50 mg/kg group was higher than in other groups(P<0.05);dietary mulberry leaf flavonoids could increased the gut flora diversity of shrimp by increasing Shannon index and decreasing the Simpson index in the 50 mg/kg group as compared with the control(P<0.05);dietary mulberry leaf Flavonoids can changed the intestinal flora composition of Litopenaeus vannamei,promoted the proliferation of Proteobacteria in the intestinal tract,and inhibited the proliferation of Actinobacteri;dietary mulberry leaf flavonoids increased the relative abundance of genera Vibrio and Shewanella(P<0.05),whereas decreased the relative abundance of genera Lactococcus and Rhodococcus(P<0.05).In conclusion,According to the regression analysis,the relative abundance of vibrio was the highest when the amount of vibrio was 137.5mg/kg,supplying 50 mg/kg diet of mulberry leaf flavonoids could promote the intestinal development and increase the intestinal flora diversity of Litopenaeus vannamei,promoted the proliferation of Proteobacteria in the intestinal tract,and inhibited the proliferation of Actinobacteri,promoted the proliferation of Shewanella,and decreased the proliferationof Rhodococcus in the intestinal tract.