Effect Of L-glutamate Supplementation On Small Intestine Architecture And Function Of Digestion And Absorption In Piglets

L-Glutamate is a major oxidative fuel for the intestine,maintained the integrity of the small intestine,improve digestion and absorption function of small intestine.The present study was to investigate the effects of L-glutamate on growth performance,nutrents apparent digestibility,small intestinal architecture,intestinal amino acid receptors and transporters in piglets.The study was to analyze whether L-glutamte could improve intestinal architecture damage and absorption dysfunction by LPS induced.It will provide the technological and theoretical basis for the application of L-glutamate on livestock production.Four experiments were included in this study:Experiment 1:The present study was to investigate the effect of L-glutamate supplementation on the growth performance,nutrents apparent digestibility,blood biochemical parameters and plasma amino acid concentration in piglets.One hundred and twenty 35-day-old piglets were randomly allocated to two treatment groups,each treatment had six replicates.Control group fed a dietary with Alaine supplementation or experimental diets supplemented with 20 g/kg L-glutamate.Experiment period was 28 d.The results showed that,compared with the control group,L-glutamate didn't significant affect ADFI,ADG and F/G of piglets(P>0.05).L-Glutamate supplementation significant increased N,OM,DM,EE apparent digestibility of piglets(P>0.05).L-Glutamate supplementation significant decreased the serum LDH activity,the concentation of Cor and FT4,increased the concentration of GC(P<0.05).L-Glutamate supplementation increased the concentrations of Arg,His,Ile,leu,Met,Phe,Thr valine,Ala,Glu,Gly,Pro,Ser,Tyr and Orn in the plasma(P<0.05).L-Glutamate supplementation didn't significant affect the concentrations of Thr,Ala,Asp,Cys and Pro in the plasma(P>0.05).Dietary L-glutamate supplementation significant decreased the concentrations cadaverine and ammonium nitrogen in the excrement(P<0.05)?Experiment 2:The present study was to investigate the effect of ditary L-glutamte supplementation on small intestinal architecture and jejunal mucosa amino acid receptors and transporters in piglets.The treatments were the same as that of experimental 1.The experiment period was 28 d.The results showed that,compared with the control group,L-Glutamate supplementation significant increased the activity of pepsin and jejunal mucosa GOT and the mRNA expression of jejunal mucosa GS of piglets(P<0.05).The VH and CD in duodenal and jejunal segments were increased by dietary L-glutamte supplementation(P<0.05).Dietary L-glutamate supplementation increased the mRNA expression of jejunal mucosa occluding and ZO-1(P<0.05).Compared with the control,dietary L-glutamate supplementation significantly increased mRNA expression of CaSR,mGluRl,mGluR4 and SLC1A5 in the jejunum mucosa(P<0.05).No significant differences in the mRNA expression of T1R1,T1R3,SLC7A9,SLC6A19,SLC7A7 and SLC1A1 were observed between treatments(P>0.05).Experiment 3:The present study was to investigate the effect of dietary L-glutamate supplementation on the growth performance,nutrents apparent digestibility,blood biochemical parameters and plasma amino acids concentration in lipopolysaccharide-challenged piglets.Twenty-four barrows piglets aged 35 d were randomly allocated to 24 cages(1 piglets/cage)and assigned to LPS challenge(Saline vs.LPS)and L-glutamate supplementation(1.21%Ala vs.2%Glu)in a 2 x 2 factorial arrangement of treatments with 6 cages/treatment.The experiment period was 15 d,piglets were injected with either saline or LPS on d 11 and d 15.The results showed that,LPS challenge decreased ADFI and ADG of piglets,increased F/G(P<0.05).Dietary L-glutamate supplementation did not affect ADFI,ADG,F/G.LPS challenge increased the apparent digestibility of N,OM,DM,EE and Ash(P<0.05).Dietary L-glutamate supplementation increased the apparent digestibility of N,OM,DM and EE(P<0.05).Additionally,There were interactions between dietary L-glutamate supplementation and LPS challenge on the apparent digestibility of N,OM and DM(P<0.05).LPS challenge decreased the concentration of IGF-1,INS,GC and the activities of GOT and AKP in serum(P<0.05),increased the concentration of TNF-a,IL-6,Cor and the activities of GPT and LDH in serum(P<0.05).Dietary L-glutamate supplementation decreased the concentration of IGF-1?INS?GLU in serum(P<0.05).Dietary L-glutamate supplementation did not affect the activities of TNF-??IL-6 and IL-1? in serum(P>0.05).There was an interaction between dietary L-glutamate supplementation and LPS challenge on INS in the serum(P<0.05).LPS challenge increased the concentrations of Met?Thr?Val?Ile?Leu?Phe?His?Ser?Cit?Cys?Tyr and Orn,decreased the concentrations ofArg and Gly in the plasma(P<0.05).L-Glutamate supplementation increased the concentrations of Met,Thr,Val,Ile,Leu,Phe,His,Arg,Ser,Cit,Tyr and Orn,decreased Asp,Glu,Gly,Cys and Pro in the plasma(P<0.05).There were interactions between dietary L-glutamate supplementation and LPS challenge on the concentrations of Lys,Met,Thr,Val,Ile,Leu,Phe,His,Arg,Ser,Cit,Tyr,Orn and Pro in the plasma(P>0.05).LPS challenge increased the concentrations of tryptamine,tyramine and ammonium nitrogen in the excrement(P<0.05).L-Glutamate supplementation decreased the concentrations of tryptamine and histamine in the excrement(P<0.05).There was an interaction between dietary L-glutamate supplementation and LPS challenge on the concentrations of tryptamine in the excrement(P>0.05).Experiment 4:The present study was to investigate the effect of dietary L-glutamate supplementation on small intestinal architecture and jejunal mucosa amino acid receptors and transporters in lipopolysaccharide-challenged piglets.The treatments were the same as that of experimental 3.The experiment period was 15 d,piglets were injected with either saline or LPS on d 11 and d 15.The results showed that,LPS challenge decreased the activities of pepsin and pancreas trypsin,increased the activities of jejunal trypsin(P<0.05).Dietary L-glutamate supplementation decreased the activities of jejunal trypsin,increased the activity of pancreas trypsin(P<0.05).LPS challenge decreased the activity of GOT in jejunal moucosa,increased the mRNA expression of jejunal mucosa GLUD1(P<0.05).Dietary L-glutamate supplementation increased the mRNA expression of jejunal mucosa GLUD1(P<0.05),did not affect the activities of GOT and GPT in jejunal mucosa(P>0.05).Dietary L-glutamate supplementation and LPS challenge had synergistic effects on the mRNA expressions of GS and GLUD1 in jejunal mucosa(P>0.05).All the 3 segments of the small intestine the VH and VH/CD were decreased after LPS challenge(P<0.05).LPS challenge increased the CD of jejunum(P<0.05).Dietary L-glutamate supplementation increased the CD and decreased the VH/CD in the ileum(P<0.05).There was an interaction between dietary L-glutamate supplementation and LPS challenge on the VH of duodenum(P<0.05).LPS challenge decreased the mRNA expressions of jejunal inucosa occluding,ZO-1 and claudin-1(P<0.05).Dietary L-glutamate supplemcntation increased the mRNA expression of jejunal mucosa occluding,ZO-1 and claudin-1(P<0.05).There were interactions between dietary L-glutamate supplementation and LPS challenge on the mRNA expression of jejunal mucosa claudin-1 and ZO-1(P<0.05).The administration of LPS significantly increased the mRNA expressions of CaSR,T1R1,T1R3,mGluRl and mGluR4,decreased the mRNA expressions of SLC1A5 and SLC1A3 in jejunal mucosa(P<0.05).Simultaneously,dietary L-glutamate supplementation increased the mRNA expressions of CaSR,T1R1,mGluR1,mGluR4,SLC1A5,SLC7A9 and SLC1A3 in jejunal mucosa(P<0.05).There were interactions between dietary L-glutamate supplementation and LPS challenge on the mRNA expressions of T1R1,mGluR1,mGluR4,SLC1A5 and SLC1Alin jejunal mucosa(P<0.05).As stated above,the conclusions are as follows:(1)Dietary L-glutamate supplementation did not affect growth performance of piglets,but increased the apparent digestibility of nutrients,increasing the concentrations of many amino acids in the plasma,improve intestine architecture,increased the mRNA expression of jejunal mucosa amino acid receptors and transporter.(2)LPS challenge increased the concentration of inflammatory cytokines in the serum,damaged the intestine architecture and the balance of the plasma amino acid concentrations.LPS challenge decreased the mRNA expression of amino acid transporters in the jejunal mucosa.The protective role of L-glutamate for LPS challenged piglets is limited.But,dietary L-glutamate supplementation and LPS challenge can greatly cause overexpression of amino acid receptors in jejunal mucosa of piglets.