Effects Of Four Organic Acids On Growth,Immunity And Intestinal Flora Of Litopenaeus Vannamei

This article first selects four organic acids: sodium citrate,sodium butyrate,sodium propionate and fumaric acid to study the effect of adding organic acids to low fish meal feed on the growth,immunity and intestinal health of Litopenaeus vannamei.Then select the sodium citrate to set up a two-factor experiment,set different levels of fish meal protein substitution and sodium citrate addition,to study the interaction between soybean meal substitution level and sodium citrate level on the growth,immunity,digestion and intestinal flora of Litopenaeus vannamei.It was expected to provide a theoretical basis for reducing the use of fish meal in shrimp feed and optimizing feed formula.The main contents are as follows:1.A feeding trial was conducted to study the effects of dietary organic acids on the growth and intestinal health of Litopenaeus vannamei fed with low fish meal diets.720 shrimp with initial weight of 7.54±0.40 g were randomly divided into 18 cages,each cage had40 tails.The trial lasted for 42 days.Six diets were consisted of a positive control diet with24% fish meal,a negative control diet with 18% fish meal and four experimental diets which formulated by adding sodium citrate,sodium butyrate,sodium propionate and fumaric acid at0.3% to the negative control diet respectively.Results demonstrated that the WGR and SGR in the negative control group were reduced and the FCR increased significantly compared with the positive control group.After adding 0.3% sodium butyrate and sodium citrate,the SGR and WGR increased and FCR decreased,however,dietary 0.3% sodium propionate and fumaric acid did not influence the WGR and SGR of shrimp significantly.The immunity of shrimp in the negative control group were decreased compared with the positive control group,but which improved after adding 0.3% sodium citrate and sodium butyrate,the activities of serum ACP,AKP,LSZ and SOD increased and the MDA content decreased,the activities of serum ACP and the MDA content were not significantly different from the positive control group(P>0.05).Compared with the negative group,the serum MDA content in shrimp fed diets with 0.3% sodium propionate decreased(P<0.05),but the immunity of shrimp in 0.3%fumaric acid group had no advantage.The Alpha diversity of the shrimp intestinal flora in each group was no significant difference(P>0.05).The abundance of Actinomycota in the negative control group decreased,while which was improved after adding 0.3% sodium citric,as well as the abundance of Bifidobacterium and Bacteroides(P<0.05).0.3% sodium butyrate increased the abundance of Fusobacterium.Generally,the low fish meal diet supplemented with organic acids can improve the growth and immune capacity of Litopenaeus vannamei,and regulate the balance of intestinal microorganism,among which0.3% sodium citrate and 0.3% sodium butyrate have the best effects.2.This experiment was conducted to study the effect of fish meal protein replacement level and sodium acid level on the growth,immunity,digestion and intestinal health of Litopenaeus vannamei.1080 shrimp with initial weight of 7.73±0.47 g were randomly divided into 27 cages,each cage had 40 tails.The trial lasted for 42 days.Using a 3×3 two-factor experimental design,9 kinds of diets were formulated with fish meal protein(FMP)substitution levels(20%,30% and 40%)and sodium citrate addition levels(0%,0.3% and0.6%)respectively,denoted as 20/0,20/0.3,20/0.6,30/0,30/0.3,30/0.6,40/0,40/0,40/0.6.Results demonstrated that WGR,SGR,and PER increased at first and then decreased,while FCR decreased at first and then increased with the increase of FMP substitution level.PER was the highest in the 30% substitution group.The WGR,SGR and PER increased and FCR decreased with the increase of sodium citrate level,the WGR and SGR of shrimp fed with diets containing sodium citrate were significantly higher than those fed diets without sodium citrate(P<0.05).The interaction of FMP substitution level and sodium citrate level significantly affected the WGR,SGR and PER,which reached the peak at 20/0.6 and 30/0.3group.With the increase of the FMP substitution level,crude lipid and crude protein decreased and crude ash increased.With the increase of sodium citrate level,crude lipid and crude ash decreased at first and then increased and crude protein decreased.The interaction of FMP substitution level and sodium citrate level significantly affected crude protein,which was higher than others at 20/0.3 group,the crude lipid at 30/0.3 group was significantly higher than 40/0 group.With the increase of FMP substitution level,the ACP,GPT and SOD activities of the blood decreased and are no significant difference between the 20% and 30%replacement groups,the ACP,AKP,SOD activities of the pancreatic and the AKP,GOT,LSZ,PPO,GSH-px activities and the MDA content of the blood increased at first and then decreased.With the increase of sodium citrate level,the ACP,SOD activities of the pancreatic and the AKP,GOT,SOD,PPO,GSH-px,CAT activities and the MDA content of the blood increased at first and then decreased and the blood PPO and GSH-px activities of the 0.6%supplement group were significantly higher than 0% and 0.3% group(P<0.05).The interaction of FMP substitution level and sodium citrate level significantly affected antioxidant capacity and antioxidant capacity,which were significantly higher than 40/0group at 20/0 and 30/0.3 group(P<0.05).With the increase of the FMP replacement level,the trypsin,amylase,lipase,and intestinal lipase of the hepatopancreas increased at first and then decreased and the 30% group was significantly higher than the 20% group(P<0.05).With the increase of sodium citrate level,the amylase and lipase activity of hepatopancreas and the lipase activity of intestinal increased at first and then decreased and the 0.3% addition group was significantly higher than the 0% group(P<0.05).The interaction of FMP substitution level and sodium citrate level significantly affected digestive enzyme activities,which were significantly higher than the 40/0 group at 30/0.3 group.The results of the study showed that the growth,immunity,antioxidant capacity and digestive enzyme activities of the shrimps were the best in the experimental group with 30% protein replacement level and 0.3% sodium citrate level.3.This experiment was based on experiment 2 to study the effect of fish meal protein replacement level and sodium acid level on the intestinal and intestinal flora of Litopenaeus vannamei.The results showed that the main structural composition of the intestinal flora and intestinal content flora in each group was basically the same at the phylum level,and the species richness and species diversity of the intestine and intestinal content at 30/0.3 group accounted for both advantages,the relative abundance of the cyanobacteria and floxanthellae with the intestinal and intestinal contents in the 30% fish meal protein substitution level group was significantly higher than that in the 20% group.As the increasing of citric acid level,there was no significant difference in the relative abundance of floxanthellae in the intestinal flora and intestinal content flora,but the relative abundance of floxanthellae in the intestinal flora was lower than that in the intestinal content flora.Under different fish meal protein substitution levels,the relative abundance of the cellulophages and bacilli showed an upward trend and the chromobacteria showed a downward trend in the intestinal flora with the increasing of citric acid level,the relative abundance of the bifidobacterium longum in the intestinal content flora increased significantly in the 0.3% sodium acid level group.Under the interaction of the both,the relative abundance of the rheinheimer at 20/0 group and the relative abundance of the christensenaceae at 40/0 group increased significantly with the intestinal flora.However,when the fish meal protein replacement level was 40%,the relative abundance of christensenaceae in the intestinal flora decreases significantly with the increasing of citric acid level.Generally,the intestinal flora balance of Litopenaeus vannamei was optimal when the fish meal protein replacement level was 30% and the sodium acid level was 0.3%,and 0.3% sodium citrate level promotes the growth of beneficial bacteria.