Effects Of Sangrovit Supplementation In Diet With High Level Of Histamine On Growth Performance,Intestinal And Liver Health Of Juvenile American Eel(Anguilla Rostrata)

In recent years,the studies on sangrovit as a functional feed additive to improve growth performance under different stresses increase gradually,while there is no research on the application of sangrovit to alleviate high level histamine diet stress.In the present study,different levels of sangrovit were supplemented in American eel(Anguilla rostrata)diet with high level of histamine.The changes in parameters related to growth performance,serum biochemistry,health status in intestine and liver were used to evaluate the supplementation effect of sangrovit,which could provide the reference for the sangrovit application in the eel(Anguilla spp.)diet.Four hundred juvenile American eels(16.01±0.03 g)were randomly divided into four groups,and they were CON group fed basal diet,H group fed diet with high level histamine(basal diet supplemented with 500 mg/kg histamine),H+SAN100 group(diet with high level histamine+100 mg/kg sangrovit),and H+SAN200 group(diet with high level of histamine+200mg/kg sangrovit),respectively.The trial period was ten weeks.The main results were as follows:(1)Effects of sangrovit supplementation in diet with high level of histamine on growth performance and biochemical parameters in serum of juvenile American eelIn comparison with the CON group,the final body weight,weight gain rate,specific growth rate,feed efficiency,and feed intake in the H group were significantly decreased(P<0.05).The levels of blood urea nitrogen,triglyceride,total cholesterol,and low-density lipoprotein cholesterol in serum of the H group were increased(P<0.05),and the levels of high-density lipoprotein cholesterol,Ig M,C3,and the activities of histamine-N-methyltransferase,phosphatase were significantly decreased(P<0.05).Dietary sangrovit supplementation could alleviate the growth inhibition caused by high level of histamine,and significantly improve in the final body weight,weight gain rate and specific growth rate,feed efficiency,and feed intake(P<0.05).Compared with the H group,the levels of blood urea nitrogen,triglyceride,total cholesterol,and low-density lipoprotein cholesterol in serum of the H+SAN100 group and H+SAN200 group were significantly decreased(P<0.05);the levels of high-density lipoprotein cholesterol,Ig M,C3 and the activities of histamine-N-methyltransferase,acid phosphatase,and alkaline phosphatase were significantly increased(P<0.05).No significant difference was observed among the CON group,H+SAN100group and H+SAN200 group in terms of growth performance and serum biochemical parameters(P>0.05).(2)Effects of sangrovit supplementation in diet with high level of histamine on intestinal health of juvenile American eelThe intestinal lipase activity in the H group was significantly decreased in comparison with the CON group(P<0.05).High level histamine diet resulted in intestinal microvilli atrophy and significantly decreased the intestinal villus length and muscular thickness(P<0.05).The level of serum D-lactate and the activity of diamine oxidase in the H group were significantly increased in comparison with the CON group(P<0.05).The expression level of intestinal epithelial tight junction protein(ZO-1)in the H group were significantly decreased(P<0.05).The activities of intestinal antioxidant enzymes were significantly decreased(P<0.05),and the level of intestinal malondialdehyde was significantly increased(P<0.05).The expression levels of TNF-α,IFN-γ,and NF-κB in the H group were significantly up-regulated(P<0.05),the expression levels of intestinal IL-10 and TGF-β in H group were significantly down-regulated(P<0.05).Compared with the H group,the intestinal lipase activity in the H+SAN100 group and H+SAN200 group was significantly increased(P<0.05).Dietary sangrovit could alleviate intestinal morphology and pathology pathological changes caused by high level of histamine.The level of D-lactate and the activity of diamine oxidase in serum of the H+SAN100 group and H+SAN200 group were significantly decreased(P<0.05).The expression level of intestinal ZO-1 was significantly increased compared to the H group(P<0.05).The intestinal antioxidant ability in H+SAN100 group and H+SAN200 group elevated,and a significant increase in the activities of intestinal antioxidant enzymes was observed compared to the H group(P<0.05).Besides,the expression levels of TNF-α,IFN-γ,and NF-κB in the H+SAN100 group and H+SAN200 group were significantly down-regulated(P<0.05),and the expression levels of intestinal IL-10 and TGF-β were significantly up-regulated in comparison with the H group(P<0.05).No significant difference was observed among the CON group,H+SAN100 group,and H+SAN200 group in terms of intestinal digestive enzyme activities,intestinal morphology,parameters related to the intestinal physical barrier,intestinal antioxidant ability,and the expression levels of intestinal inflammatory genes(P>0.05).The results of intestinal flora and intestinal metabolism of juvenile American eel among the CON group,the H group,and the H+SAN100 group were shown as following.There were no significant changes in Chao1 index,observed＿species,PD＿whole＿tree and Shannon among the three treatment groups(P>0.05).At the phylum level,the relative abundance of Bacteroidetes and Fusobacteria in the H group tended to be increased,and the relative abundance of Firmicutes and Proteobacteria in the H group tended to be decreased.The CON group and the H+SAN100group showed the similar composition of intestinal flora at phylum level with relative abundance of bacterial population similarly.At the genus level,the relative abundances of s＿Bacillus＿galactosidilyticus and s＿Weissella＿viridescens were significantly higher in the CON group(P<0.05),the relative abundances of g＿Mycoplasma,g＿Bacteroides and g＿Oceanobacillus were significantly higher in H group(P<0.05),the relative abundances of g＿Plesiomonas,g＿Curvibacter,and g＿Franconibacter were significantly higher in H+SAN100 group(P<0.05).Compared with the CON group,the levels of acetylcholine,arginine,isoleucine,phosphoenolpyruvic acid,phenylpyruvic acid,phosphoenolpyruvic acid were up-regulated in H group,and the level of L-isoleucine was downregulated.The actin cytoskeleton,biosynthesis of amino acids,phenylalanine,tyrosine and tryptophan biosynthesis,citrate cycle(TCA cycle)and arginine biosynthesis were affected.Compared with the H group,the levels of tetrahydrofolic acid,mesylate,and L-serine were up-regulated in H+SAN100 group,and the level of sphinganine was downregulated,the Gn RH signaling pathway,one carbon pool by folate,sphingolipid metabolism,sulfur metabolism,glycine,serine and threonine metabolism and ABC transporters were affected.(3)Effects of sangrovit supplementation in high level histamine diet on liver health of juvenile American eelThe hepatic histopathology of juvenile American eel was affected by high level of dietary histamine,and the hepatocyte vacuolar degeneration and nuclear deviation were observed.The supplementation of 100 mg/kg and 200 mg/kg sangrovit might alleviate those pathological changes by high level of dietary histamine.Besides,high level of dietary histamine significantly elevated the activities of serum glutamic-pyruvic transaminase and glutamic-oxalacetic transaminase(P<0.05).High level histamine diet decreased the liver antioxidant ability(P<0.05).No significant difference was observed among the CON group,H+SAN100 group,and H+SAN200 group in terms of serum transaminase activity,liver morphology,and liver antioxidant ability(P>0.05).The levels of glutamate,ergothionine,oxoglutaric acid,histidine trimethyl betaine acid,methylimidazoleacetic acid,arachidonic acid,and methylhistamine in the liver of juvenile American eel were up-regulated in H group-CON group,the levels of taurine and taurocholic acid were down-regulated.The histidine metabolism,Fox O signaling pathway,taurine and hypotaurine metabolism,and Gn RH signaling pathway were regulated.Compared with H group,the levels of taurine,taurocholic acid,ureidopropionic acid,uracil,and 9-cis-Retinoic acid in the liver of juvenile American eel were up-regulated in H+SAN100 group,the level of mannose was down-regulated.Intestinal immune network for Ig A production,Lysosome,PPAR signaling pathway,taurine and hypotaurine metabolism,and β-Alanine metabolism were affected in H+SAN100 group.In conclusions,100 mg/kg sangrovit supplemented in diet with high level of histamine could promote growth performance,enhance intestinal lipase activity,improve intestinal and liver antioxidant capacity,alleviate intestinal inflammation,improve the intestinal barrier,positively regulate intestinal flora,affect intestinal and liver amino acid metabolism,energy metabolism and lipid metabolism.