Effects Of Dietary Black Rice On Growth,immune And Intestinal Health Of Procambarus Clarkii

In 2021,the production of Procambarus clarkii,commonly known as the red swamp crayfish,reached 2.6336 million tons,with the scale of aquaculture increasing annually.However,due to issues such as abnormal feeding and excessive stocking density during the farming process,the economic benefits of Procambarus clarkii aquaculture have been unstable.Problems such as stunted growth,unsuccessful molting,and frequent occurrence of enteritis have been observed.With the ban on antibiotic use,the use of green additives in feed to promote growth and enhance immune function in aquaculture has become a current research focus in the aquaculture industry.The polyhydroxy structure of anthocyanins determines their strong antioxidant capacity,and black rice is rich in anthocyanins.In order to investigate the efficacy of black rice anthocyanins as feed additives,this study analyzed the effects of anthocyanin supplementation on the growth performance,immune function,and intestinal microbiota composition of Procambarus clarkii.The research results are as follows:1.Effects of Anthocyanins on the Growth,Antioxidant Capacity,and Intestinal Health of Procambarus clarkiiFeeds without anthocyanin supplementation were used as the control,and feeds with20% and 40% black rice(BR)and 0.8% and 0.16% anthocyanin extract(AC)were added,designated as CON,BR200,BR400,AC200,and AC400.After an eight-week feeding experiment,the results showed that the final body weight,weight gain rate,and specific growth rate of Procambarus clarkii in the BR400,AC200,and AC400 groups were significantly higher than those in the control group(P<0.05).The survival rate in the BR400 and AC400 groups was significantly higher than that in the control group(P<0.05).The addition of black rice anthocyanins in the feed reduced the feed conversion ratio of Procambarus clarkii,with the BR200 group showing a significantly lower feed conversion ratio than the other groups(P<0.05),and the BR400 and AC200 groups showing a significantly lower feed conversion ratio than the CON group(P<0.05).The T-AOC,SOD,and PPO activities in the four anthocyanin-added groups were significantly higher than those in the CON group.The PPO activity in the BR400 and AC400 groups was significantly higher than that in the CON group.The T-AOC in the BR400 and AC400 groups was significantly higher than that in the control group(P<0.05).In the liver and pancreas,the T-AOC,PPO,and SOD levels in the BR400 and AC400 groups were significantly higher than those in the CON group(P<0.05).The T-AOC levels in the BR200,BR400,and AC400 groups were significantly higher than those in the CON group.The PPO activity in the BR400 group was significantly higher than that in the CON group.The SOD activity in the anthocyanin-added groups was significantly higher than that in the CON group(P<0.05).The ACP and AKP activities in the blood lymph and intestine of the anthocyanin-added groups were significantly higher than those in the CON group.In the liver and pancreas,the ACP and AKP activities in the BR400 and AC400 groups were significantly higher than those in the CON group(P<0.05).Anthocyanins improved the intestinal morphology of Procambarus clarkii,with the villus height/crypt depth ratio being significantly higher in the BR200,BR400,and AC400 groups compared to the control group(P<0.05).Anthocyanins also enhanced the activity of digestive enzymes in the intestine,with the amylase activity in the anthocyanin-added groups being significantly higher than that in the CON group,the lipase activity in the BR400 group being significantly higher than that in the CON group,and the trypsin activity in the BR200,BR400,and AC400 groups being significantly higher than that in the CON group(P<0.05).2.The Alleviating Effect of Anthocyanins on LPS-Induced Apoptosis in Procambarus clarkii HemocytesProcambarus clarkii,which underwent an eight-week feeding experiment,was injected with LPS at a concentration of 2 mg/ml.The groups were divided as follows:CON+LPS,BR200+LPS,BR400+LPS,AC200+LPS,AC400+LPS,and the control group(CON+NS),which received the same dosage of saline.The results showed that LPS injection significantly increased the apoptosis rate of blood cells,with the apoptosis rate in the CON+LPS group being significantly higher than that in the CON+NS group(P<0.05).Feeding Procambarus clarkii with anthocyanins significantly reduced the apoptosis rate(P<0.05),and the apoptosis rate in the AC400+LPS group was significantly lower than that in the other groups(P<0.05).After LPS injection,the NO content and SOD activity in the blood lymph,liver,pancreas,and intestine significantly increased.The addition of anthocyanins in the feed reduced the NO content and SOD activity in the blood lymph,liver,pancreas,and intestine(P<0.05).LPS-induced a significant decrease in PPO activity in the blood lymph,liver,pancreas,and intestine,while anthocyanins significantly increased PPO activity(P<0.05).LPS attack led to a decline in immune function in Procambarus clarkii,with a significant decrease in AKP and ACP activities in the blood lymph,liver,pancreas,and intestine.Feeding Procambarus clarkii with anthocyanins significantly increased AKP and ACP activities(P<0.05).In conclusion,the addition of anthocyanins in feed has a promoting effect on the growth,immune function,and intestinal health of Procambarus clarkii.The appropriate dosage of anthocyanins is 400 mg/kg.