Weaning of piglets is generally considered as a stressor which changes intestinal ecosystem and leads to clinical implications. Microbiota inhabiting in small intestine （especially ileum） are assumed to promote health, but their functional properties are yet poody dascdbed. As indicated by the 16S rRNA gene sequences of ileal micrebiota in nursing piglets （at the age of 21 and 28 d） and 28-day-old weaned piglets （weaned at 21 d of age）, the microbiota were mainly comprised of gram-positive bacteria. There were 40 operational taxonomic units （OTUs） （from 171 clones） in the ileum of nursing piglets aged 21 d, 61 OTUs （from 194 clones） in the ileum of nursing piglets aged 28 d, and 56 OTUs （from 171 clones） in the ileum of weaned piglets aged 28 d. The flea of nursing piglets aged 21 d were dominantly occupied by Lactobacilli （87.7%） as well as Streptococ cus （ 3.5 % ）. Lactobacillus amy/ovorus （41.5 % ）, Lactobaci/lus sp. （ 19.3 % ）, Lactobaci/lus reuteri （ 12.3 % ）, Lactobacillus salivarius （ 9.4 % ） and L. mucosae （4.7%） were the predominant species among Lactobacil/L Similar results were obtained in the nursing piglets at 28 d of age ex- cept that Lactobaci/li decreased to 71.1% and Streptococcus increased to 21.1% significantly. Lactobacillus （52.0%） and Streptococcus （26.3%） were the two major groups in the ileum of weaned piglets aged 28 d. Lactobacillus amylovorus （31.6%） and Lactobaci/lus reuteri （ 16.4% ） was the two most important species in Lactobacillus. Therefore, Lactobacilli were predominant in the ileum of nursing and weaned piglets, and they had the highest diversity, followed by Streptococcus. The diversity of ileal microbiota was not different remarkably between the nursing piglets and the weaned piglets, but the composition changed significantly. These findings are helpful to understand ileal bacterial ecophysiology and further develop nutritional regimes to prevent or counteract complications during the weaning transition.
Dietary arginine supplementation enhances the immune status and protein synthesis in early-weaned pigs. However, the underlying mechanisms remain largely unknown. To investigate how arginine affects the expression of key proteins that regulate growth and nutrient transport of jejunum, a total of 12 healthy piglets （21 day-old, similar body weight, Landrace x Yorkshire） delivered by four sows were randomly divided into two groups. Piglets in the test group were reared with feed supplemented L-arginine at a concentration of 6.0 g/kg, while piglets in the control group were fed with feed supplemented L-alanine at a concentration of 12.3 g/kg （isonitrogenous control）. After 7 d, jejunum mucosae was collected and analyzed with the 2-D PAGE MS technology. Compared with the control pigs, arginine decreased the levels of proteins that regulate the protein syn- thesis, intermediary metabolism and tissue growth （ similar to anterior gradient 2 homolog, cyclophilin_ABHJike, hypothetical protein FLJ39502 and tetratrioopeptide repeat domain 16, similar to KIAA0156, mitechondrial ATP synthase, hydrion transporting F1 complex, beta subunit and alpha-tu- bulin ubiquitous isoform 19, prolyl 4-hydroxylase, beta subunit precursor）. In addition, arginine increased the levels of proteins that are involved in proteolysis and immune response （ PGAM1, T cell receptor beta variable 20, membrane steroid binding protein, similar to myomesin-1, and chain A, structure of pig muscle Pgk complexed with MgATP）. Therefore, arginine influences the immune response and protein synthesis mechanisms as well as improves eady weaned stress syndrome of piglets.
[ Objective] To profile the differentially expressed genes in small intestine between piglets with intrauterine growth restriction （IUGR）, describe the relationships between growth performance and gene expression in IUGR piglets, and thus provide a theoretical basis for further research. [Metbed] Eight suckling piglets at the age of 21 d Efour with normal body weight （NBW） of （1 503 ± 310） g and four with low BW of （806 ±35） g] were killed, and the intestinal samples were collected. Gene expression was detected by Affymetrix Porcine GeneChip and further confirmed by quantitative real-time PCR. [ ReseltJ Microarray analysis showed that there were 156 differentially expressed genes in the small intestine between the IUGR piglets and the age-matched NBW piglets, including 61 down-regulated genes and 95 up-regulated genes, The up-regulated genes included protein tyrosine phosphatase, myosin, troponin, heat shock protein, metallothionein, arginine vasopressin-induced 1, ribosomal protein L6, apoptosls antagonizing transcription factor, muscle creatine kinase, mannosidase, lysozyme, folliculin, urate transporterchannel protein, pyrroline-5-carboxylate reductese-like, and adenine phosphor-dbosyltransferase. The down-regulated genes included protein kinase, arachidohate 12-1ipoxygenase, transcription factor A, GTP-GDP dissociation stimulator 1, serine （or cysteine） proteinase inhibitor, fetuin, dolichol-phosphate-mannose synthase, apolipoprotein H, argininosuccinate synthetase 1, iron-regulated transporter, alpha-2-macroglobulin, immunoglobulin superfamily, thioltransferase, and guanylate binding protein 2. The gene expression profile changed in the small intestine of piglets with intrauterine growth restriction, providing a theoretical basis for eady intervention in growth restriction.
