Dietary Arginine supplementation can improve the weaned stress syndrome of early-weaned piglets.However,the underlying mechanisms are largely unknown.This study was conducted by using piglet model and proteomics technology to disclose the effect of dietary arginine supplementation on the expression of key proteins that regulate growth and nutrient transportation of the jejunum,liver and muscle.Twelve,21-d-old healthy piglets (LandracexYorkshire) were removed from 4 sows and divided int0 2 groups randomly.The test group was supplemented with 0.6% L-arginine,the control group was fed with 1.23% L-alanine (isonitrogenous controI).Compared with control pigs,the Arginine group decreased the levels of proteins that regulate the protein synthesis,intermediary metabolism and tissue growth (similar to anterior gradient 2 homolog,similar to Peptidyl-prolyl cis-trans isomerase B precursor,hypothetical protein FLJ39502 and tetratricopeptide repeat domain 16,Similar to KIAA0156,mitochondrial ATP synthase,H+ transporting Fl complex beta subunit + alpha-tubulin ubiquitous isoform 19,Non-selenium glutathione peroxidase,Chain A,Steric And Conformational Features Of The Aconitase Mechanism).In addition,Arginine mcreased the levels of proteins that are involved in proteolysis and immune response (PGAMl and T cell receptor beta variable 20,Membrane steroid binding protein,Similar to Myomesin-1,Chain A,Structure Of Pig Muscle Pgk Complexed With Mgatp,Chain A,Polylysine Induces An Antiparallel Actin Dimer That Nucleates Filament Assembly: Crystal Structure At 3.5 A Resolution,etc).These significant findings suggest that Arginine can influence the immune response,protein synthesis mechanisms for improving early weaned stress syndrome of early-weaned piglets.