Effects Of The Low Protein Diet Supplemented With Enough Essential Amino Acids And Cysteamine Supplementation On Intestinal Health In Finishing Pigs

The intestinal tract is an important part of the animal digestive system,the intestinal health maintenance plays an important role for animals to absorb nutrients.Cysteamine is the natural growth promoting substance in animals,to maintain the integrity of the intestinal mucosal barrier,to protect the intestinal health.The low protein diet supplemented with enough essential amino acids(EAA)could reduce the use of protein feed raw materials,reducing nitrogen emissions.The present study was to investigate the effects of The low protein diet supplemented with enough EAA and cysteamine supplementation on gastrointestinal hormone secretion,small intestine architecture,intestinal antioxidant function and the intestinal mucosa barrier.The research results will provide the technological and theoretical basis for the application of the low protein diet supplemented withenough EAA and cysteamine on pig production.One hundred twenty barrow(Yorkshire × Landrace × Meishan)pigs with an average initial body weight of 66kg were randomly allocated into four treatments using a 2 × 2 factorial arrangement with five replicates(pens)and six pigs each.The primary variations of this experiment were the dietary CP levels(14%or 10%)and CS supplemental levels(0 or 140 mg/kg).The pigs were fed with one of the four diets,as follows:[normal protein level diet(NP)(14%CP),NP supplemented with CS,low protein level diet(LP)(10%CP),and LP supplemented with CS].Experiment period was 41d.The results showed that,cysteamine supplementation significant decreased somatostatin(SS)concentrations in the small intestine(P<0.05),significant increased vasoactive intestinalpeptide(VIP)?Glucagon-like peptide-2(GLP-2)and Ghrelin concentrations in the duodenum and jejunum(P<0.05),significant increased VIP concentrations(P<0.05)and didn't significant affect GLP-2 and Ghrelin concentrations in the ileum(P>0.05).Dietary protein levels didn't significant affect the gastrointestinal hormone concentrations in the small intestine(P>0.05).Cysteamine supplementation significant increased VH and VH/CD(P<0.05)and didn't significant affect CD(P>0.05)in the duodenum,significant increased VH(P<0.05)and didn't significant affect CD and VH/CD(P>0.05)in the jejunum,didn't significant affect the ileum architecture(P>0.05).Dietary protein levels didn't significant affect the small intestine architecture(P>0.05).Cysteamine supplementation significant increased the activity of alkaline phosphatase(AKP)in the duodenum and jejunum(P<0.05),didn't significant affect the activity of alkaline phosphatase(AKP)in the ileum(P>0.05).Dietary protein levels didn't significant affect the activity of alkaline phosphatase(AKP)in the small intestine(P>0.05).In the duodenum and jejunum,Cysteamine supplementation significant increased the total antioxidant capacity(T-AOC),the glutathione(GSH)concentrations and the activity of the glutathione peroxidase(GSH-Px)(P<0.05),significant decreased the malondialdehyde(MDA)concentrations(P<0.05),didn't significant affect the activity of T-SOD and CAT(P>0.05).In the ileum,Cysteamine supplementation significant increased the activity of the GSH-Px(P<0.05),didn't significant affect the T-AOC,the activity of the T-SOD,CAT and the GSH-Px and the MDA?GSH concentrations(P>0.05).Dietary protein levels didn't significant affect the antioxidant capacity in the small intestine(P>0.05).Cysteamine supplementation significant increased the Claudin-1?Occludin and ZO-1'mRNA relative expression in duodenum and jejunum(P<0.05),significant increased the Claudin-1 and Occludin'mRNA relative expression in ileum(P<0.05),didn't significant affect ZO-1'mRNA relative expression in ileum(P>0.05).Dietary protein levels didn't significant affect the tight junction protein'mRNA relative expression in the small intestine(P>0.05).Cysteamine supplementation significant increased the number of small intestinal intraepithelial lymphocytes in thesmall intestine(P<0.05).Dietary protein levels didn't significant affect the number of small intestinal intraepithelial lymphocytes in the small intestine(P>0.05).Cysteamine supplementation significant increased the IL-2'mRNA relative expression in the duodenum and jejunum(P<0.05),didn't significant affect the IL-2'mRNA relative expression in the ileum(P>0.05).Dietary protein levels didn't significant affect the IL-2'mRNA relative expression in the small intestine(P>0.05).Cysteamine supplementation significant increased the IFN-?'m RNA relative expression in the small intestine(P<0.05).Dietary protein levels didn't significant affect IFN-?'mRNA relative expression in the jejunum and ileum(P>0.05).In the duodenum,Cysteamine supplementation significant increased the concentrations of secreted immunoglobulin A(SIgA)(P<0.05),didn't significant affect the concentrations of immunoglobulin G(IgG)and immunoglobulin M(IgM)(P>0.05).In the jejunum,Cysteamine supplementation significant increased the concentrations of SIgA,IgG and IgM(P<0.05).In the ileum,Cysteamine supplementation didn't significant affect the concentrations of immunoglobulin(P>0.05).Dietary protein levels didn't significant affect the the concentrations of immunoglobulin in the small intestine(P>0.05).Cysteamine supplementation didn't significant affect the MUC-2' mRNA relative expression in small intestine(P>0.05).Dietary protein levels didn't significant affect the MUC-2' mRNA relative expression in small intestine(P>0.05).As stated above,the conclusions are as follows:(1)LP supplemented with enough EAA(the dietary CP is reduced by approximately 4 percentage units,supplemented with EAA to meet the NRC AA requirements)had not been found significant affect the intestinal health in finishing pigs.(2)Cysteamine supplementation improved the small intestine architecture,increased the antioxidant capacity,immunity and the mRNA expression of tight junction protein in the finishing pig's small intestinal mucosa.(3)There were no interactions between dietary protein levels and cysteamine supplementation for the intestinal health.Dietary protein levels and CS supplementation influenced intestinal health through independent mechanisms in finishing pigs.