Effects Of Oleanolic Acid On Growth,immunity,hepatopancreas And Intestinal Of Procambarus Clarkii

The scale and production of Procambarus clarkii farming is increasing year by year,and with the wide range and diverse patterns of farming,Procambarus clarkii are susceptible to a variety of stresses during the farming process,resulting in reduced immunity,tissue damage,disturbance of intestinal flora,slow growth and many other adverse phenomena.In order to improve the growth performance,the stress resistance and the health of Procambarus clarkii,five experimental diets with oleanolic acid levels of 0(Con group),250 mg/kg(OA250 group),500 mg/kg(OA500 group),750 mg/kg(OA750group)and 1000 mg/kg(OA1000 group)were designed in this study to To investigate the effects of oleanolic acid on the growth performance,antioxidant capacity,immune function and liver and intestinal tissue health of Procambarus clarkii.Seven hundred and fifty homogeneous,healthy and disease-free Procambarus clarkii(6±0.01 g)were randomly divided into five groups of three replicates each(50 Procambarus clarkii per replicate)and randomly placed in net boxes(2 m long,1 m wide and 1.5 m high)for 8 weeks.The results of the trials were as follows.(1)Effects of oleanolic acid on growth performance,body composition and intestinal digestive enzyme activities of Procambarus clarkiiThe weight gain rate and specific growth rate of OA500 group,OA750 group and OA1000 group increased significantly(P < 0.05).The feed conversion ratio decreased significantly(P < 0.05),and there was no significant difference in hepatosomatic index and condition factor among the groups(P > 0.05).Adding oleanolic acid in feed had no significant effect on water content,crude protein,crude fat and crude ash of Procambarus clarkii(P > 0.05).Intestinal trypsin activity increased significantly in OA500,OA750 and OA1000groups(P < 0.05).The lipase activity of OA500 group,OA750 group and OA1000 group decreased significantly(P < 0.05).The amylase activity decreased significantly in OA1000group(P < 0.05).Na + K +-ATPase activity was significantly increased in OA750 group and OA1000 group(P < 0.05).(2)Effects of oleanolic acid on hemolymph biochemistry,immune function and antioxidant capacity of Procambarus clarkiiThe activity of glutamic pyruvic transaminase decreased significantly after adding oleanolic acid(P < 0.05).The activities of aspartate aminotransferase in OA500 group,OA750 group and OA1000 group were significantly decreased(P < 0.05).The contents of glucose,total cholesterol and triglyceride in OA500 group,OA750 group and OA1000 group were significantly lower than those in control group(P < 0.05).MDA content in hepatopancreas of OA500 group,OA750 group and OA1000 group decreased significantly(P < 0.05).The activities of SOD in hepatopancreas of OA250 group,OA500 group and OA750 group were significantly higher than those of OA0 group(P < 0.05).GSH and CAT levels of hepatopancreas in OA0 group were significantly higher than those in OA0 group(P < 0.05).The expression levels of cat gene in hepatopancreas of Procambarus clarkii in OA500 group,OA750 group and OA1000 group increased significantly(P < 0.05),the expression levels of gpx gene in OA500 group and OA750 group increased significantly(P < 0.05),the expression levels of mnsod gene in OA750 group increased significantly(P < 0.05),the expression levels of nrf2 gene in oleanolic acid group increased significantly(P < 0.05),and the expression levels of keap1 gene in OA750 and OA1000 groups decreased significantly(P < 0.05).Lysozyme in hemolymph of Procambarus clarkii in OA500 group,OA750 group and OA1000 group was significantly higher than that in control group(P < 0.05).The acid phosphatase activity in OA500 group,OA750 group and OA1000 group was significantly increased(P < 0.05),and the alkaline phosphatase activity in the hemolymph of OA750 group was significantly higher than that of OA0 group(P < 0.05).The content of complement C3 in the hemolymph of oleanolic acid group was significantly increased(P <0.05),and the content of complement C4 in OA750 group and OA1000 group was significantly increased(P < 0.05).The expression level of lsz gene in hepatopancreas of Procambarus clarkii in OA500 group,OA750 group and OA1000 group increased significantly(P < 0.05),the expression level of alf gene in oleanolic acid group increased significantly(P < 0.05),the expression level of tlr gene in OA750 group and OA1000 group decreased significantly(P < 0.05),and the expression levels of nfkb and rel gene in OA500 group decreased significantly(P < 0.05).(3)Effects of oleanolic acid on liver-gut tissue structure,intestinal digestive enzymes and intestinal flora of Procambarus clarkiiIn the oleanolic acid group,the liver corpuscles were closely arranged,the shape of the hepatic tubules was regular,the lipid droplet vacuole was reduced,and the integrity of the basement membrane was good,indicating that oleanolic acid improved the liver tissue morphology and reduced the fat accumulation.The intestinal villus height in OA750 group was significantly increased(P < 0.05).The intestinal flora of OA500 and OA1000 in oleanolic acid addition group was analyzed at the phylum level,and the results showed that the proportion of Proteus decreased significantly from 33.46 % to 9.25 % and 11.06 %,respectively.Meanwhile,the proportion of Bacteroidetes increased from 4.23 % to 23.67 % and 30.46 %,respectively.The analysis at genus level showed that the proportion of Bacteroides increased significantly from 3.14 % to 20.80 % and 12.25 %,respectively.The proportion of Citrobacter decreased significantly from 30.21 % to 3.12 % and 2.33 %,respectively.This indicated that oleanolic acid could improve the intestinal flora structure and health of Procambarus clarkii.In conclusion,500 mg / kg,750 mg / kg and1000 mg / kg oleanolic acid could promote the growth of Procambarus clarkii,but had no significant effect on the whole body composition of Procambarus clarkii.Adding oleanolic acid can reduce liver function damage,improve antioxidant capacity and immune function of Procambarus clarkii;oleanolic acid could increase the trypsin level in the intestine of Procambarus clarkii,but inhibit the levels of lipase and α-amylase.Oleanolic acid improved the hepatopancreas and intestinal tissue structure of Procambarus clarkii,reduced fat accumulation in hepatopancreas,and increased intestinal villus height when the addition of oleanolic acid was 750 mg / kg.Oleanolic acid increased the proportion of intestinal beneficial bacteria and inhibited the proliferation of harmful bacteria.In conclusion,the application of oleanolic acid improved the health of Procambarus clarkii,increased the resistance of Procambarus clarkii to stress and promoted the growth of Procambarus clarkii.