This study compared late bilinguals’ pitch feedback control in L1 and L2 production using a frequency-altered feedback paradigm in which participants read target words while presented with unexpected pitch-shift in their voice feedback. Variables of language (L1 or L2) and perturbation magnitudes (0, 100, 200, or 400 cents) were manipulated. Behaviorally, participants produced larger magnitudes but longer latencies of vocal compensation in L2 than in L1 production, suggesting that L2 pitch feedback control has greater importance but lower efficiency. Event-related potential findings demonstrated that 400-cent shifts elicited greater N1 amplitudes than those in the 0-cent baseline condition in L1 production. This difference was non-significant in L2 production, implying different neural processing of unaltered feedback and externally-generated feedback in L1 and L2 production. Participants’ vocal compensation and P2 amplitudes were similarly modulated by pitch-shift in L1 and L2 production, implying a similar gating mechanism to correct internal and external errors.

Speech production requires the combined efforts of feedforward and feedback control, but it remains unclear whether the relative weighting of feedforward and feedback control is organized differently between the first language (L1) and the second language (L2). In the present study, a group of Chinese–English bilinguals named pictures in their L1 and L2, while being exposed to multitalker noise. Experiment 1 compared feedforward control between L1 and L2 speech production by examining intensity increases in response to a masking noise (90 dB SPL). Experiment 2 compared feedback control between L1 and L2 speech production by examining intensity increases in response to a weak (30 dB SPL) or strong noise (60 dB SPL). We also examined a potential relationship between L2 fluency and the relative weighting of feedforward and feedback systems. The results indicated that L2 speech production relies less on feedforward control relative to L1, exhibiting attenuated Lombard effects to the masking noise. In contrast, L2 speech production relies more on feedback control than L1, producing larger Lombard effects to the weak and strong noise. The relative weighting of feedforward and feedback control is dynamically changed as second language learning progresses.

Ca2+-sensing receptor (CaSR) represents a potential therapeutic target for inflammatory bowel diseases and strongly prefers aromatic amino acid ligands. We investigated the regulatory effects of dietary supplementation with aromatic amino acids – tryptophan, phenylalanine and tyrosine (TPT) – on the CaSR signalling pathway and intestinal inflammatory response. The in vivo study was conducted with weanling piglets using a 2 × 2 factorial arrangement in a randomised complete block design. Piglets were fed a basal diet or a basal diet supplemented with TPT and with or without inflammatory challenge. The in vitro study was performed in porcine intestinal epithelial cell line to investigate the effects of TPT on inflammatory response using NPS-2143 to inhibit CaSR. Dietary supplementation of TPT alleviated histopathological injury and decreased myeloperoxidase activity in intestine challenged with lipopolysaccharide. Dietary supplementation of TPT decreased serum concentration of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12, granulocyte-macrophage colony-stimulating factor, TNF-α), as well as the mRNA abundances of pro-inflammatory cytokines in intestine but enhanced anti-inflammatory cytokines IL-4 and transforming growth factor-β mRNA levels compared with pigs fed control diet and infected by lipopolysaccharide. Supplementation of TPT increased CaSR and phospholipase Cβ2 protein levels, but decreased inhibitor of NF-κB kinase α/β and inhibitor of NF-κB (IκB) protein levels in the lipopolysaccharide-challenged piglets. When the CaSR signalling pathway was blocked by NPS-2143, supplementation of TPT decreased the CaSR protein level, but enhanced phosphorylated NF-κB and IκB levels in IPEC-J2 cells. To conclude, supplementation of aromatic amino acids alleviated intestinal inflammation as mediated through the CaSR signalling pathway.

Skeletal muscle is a major site for the oxidation of fatty acids (FA) in mammals, including humans. Using a swine model, we tested the hypothesis that dietary protein intake regulates the expression of key genes for lipid metabolism in skeletal muscle. A total of ninety-six barrows (forty-eight pure-bred Bama mini-pigs (fatty genotype) and forty-eight Landrace pigs (lean genotype)) were fed from 5 weeks of age to market weight. Pigs of fatty or lean genotype were randomly assigned to one of two dietary treatments (low- or adequate-protein diet), with twenty-four individually fed pigs per treatment. Our data showed that dietary protein levels affected the expression of genes involved in the anabolism and catabolism of lipids in the longissimus dorsi and biceps femoris muscles in a genotype-dependent manner. Specifically, Bama mini-pigs had more intramuscular fat, SFA and MUFA, as well as elevated mRNA expression levels of lipogenic genes, compared with Landrace pigs. In contrast, Bama mini-pigs had lower mRNA expression levels of lipolytic genes than Landrace pigs fed an adequate-protein diet in the growing phase. These data are consistent with higher white-fat deposition in Bama mini-pigs than in Landrace pigs. In conclusion, adequate provision of dietary protein (amino acids) plays an important role in regulating the expression of key lipogenic genes, and the growth of white adipose tissue, in a genotype- and tissue-specific manner. These findings have important implications for developing novel dietary strategies in pig production.

Revealing the expression patterns of fatty acid and amino acid transporters as affected by dietary n-6:n-3 PUFA ratio would be useful for further clarifying the importance of the balance between n-6 and n-3 PUFA. A total of ninety-six finishing pigs were fed one of four diets with the ratio of 1:1, 2·5:1, 5:1 and 10:1. Pigs fed the dietary n-6:n-3 PUFA ratio of 5:1 had the highest (P< 0·05) daily weight gain, and those fed the dietary n-6:n-3 PUFA ratio of 1:1 had the largest loin muscle area (P< 0·01). The concentration of n-3 PUFA was raised as the ratio declined (P< 0·05) in the longissimus dorsi and subcutaneous adipose tissue. The contents of tryptophan, tasty amino acids and branched-chain amino acids in the longissimus dorsi were enhanced in pigs fed the dietary n-6:n-3 PUFA ratios of 1:1–5:1. The mRNA expression level of the fatty acid transporter fatty acid transport protein-1 (FATP-1) was declined (P< 0·05) in the longissimus dorsi of pigs fed the dietary n-6:n-3 PUFA ratios of 1:1–5:1, and increased (P< 0·05) in the subcutaneous adipose tissue of pigs fed the dietary n-6:n-3 PUFA ratios of 5:1 and 10:1. The expression profile of FATP-4 was similar to those of FATP-1 in the adipose tissue. The mRNA expression level of the amino acid transceptors LAT1 and SNAT2 was up-regulated (P< 0·05) in the longissimus dorsi of pigs fed the dietary n-6:n-3 PUFA ratios of 1:1 and 2·5:1. In conclusion, maintaining the dietary n-6:n-3 PUFA ratios of 1:1–5:1 would facilitate the absorption and utilisation of fatty acids and free amino acids, and result in improved muscle and adipose composition.

Tributyrin (TBU) is a good dietary source of butyrate and has beneficial effects on the maintenance of normal intestinal morphology. The present study tested the hypothesis that dietary TBU supplementation could alleviate intestinal injury in the acetic acid (ACA)-induced porcine model of colitis. A total of eighteen piglets (25 d old) were randomly allocated to one of three treatment groups (control, ACA and TBU). The control and ACA groups were fed a basal diet and the TBU group was fed the basal diet supplemented with 0·1 % TBU. On day 15 of the trial, under anaesthesia, a soft catheter was inserted into the rectum of piglets (20–25 cm from the anus), followed by administration of either saline (control group) or ACA (10 ml of 10 % ACA solution for ACA and TBU groups). On day 22 of the trial, after venous blood samples were collected, piglets were killed to obtain mid-ileum and mid-colon mucosae. Compared with the control group, the ACA group exhibited an increase (P< 0·05) in lymphocyte counts, creatinine, PGE2, and malondialdehyde concentrations and diamine oxidase and inducible NO synthase activities in the plasma and lymphocyte density in the colon and a decrease in insulin concentrations and glutathione peroxidase activity, ileal villus height:crypt depth ratios and goblet cell numbers in the colon. These adverse effects of ACA were attenuated by TBU supplementation. Moreover, TBU prevented the ACA-induced increase in caspase-3 levels while enhancing claudin-1 protein and epidermal growth factor receptor (EGFR) mRNA expression in the colonic mucosa. Collectively, these results indicate that dietary supplementation with 0·1 % TBU alleviates ACA-induced intestinal injury possibly by inhibiting apoptosis, promoting tight-junction formation and activating EGFR signalling.

The objective of the present study was to investigate the optimal dietary n-6:n-3 PUFA ratios that regulate lipid metabolism and inflammation in pigs. A total of ninety-six cross-bred (Large White × Landrace) growing-finishing pigs (73·8 (sem 1·6) kg) were chosen and fed one of the four isoenergetic diets with n-6:n-3 PUFA ratios of 1:1, 2·5:1, 5:1 and 10:1. The growth performance of pigs fed the diet with an n-6:n-3 PUFA ratio of 5:1 was the best, but the group fed the diet with an n-6:n-3 PUFA ratio of 1:1 had the highest muscle mass and the lowest adipose tissue mass (P< 0·05). The concentrations of IL-6 and IL-1β of pigs fed the diet with an n-6:n-3 PUFA ratio of 1:1 were decreased compared with those of the other groups (P< 0·05). The concentration of adiponectin of pigs fed the diet with an n-6:n-3 PUFA ratio of 1:1 was also markedly decreased, but the concentration of leptin was increased compared with that of the groups fed the diets with n-6:n-3 PUFA ratios of 5:1 and 10:1 (P< 0·05). Additionally, the optimal dietary ratios of n-6:n-3 PUFA of 1:1 and 5:1 markedly suppressed the expression levels of lipid metabolism-related genes and proteins such as phosphoinositide-3-kinase-α, fatty acid transport protein-1 and PPARγ. They also significantly suppressed the expression levels of the inflammatory cytokines IL-1β, TNF-α and IL-6. The results indicated that the optimal n-6:n-3 PUFA ratios of 1:1 and 5:1 exerted beneficial effects on lipid metabolism and inflammatory system, leading to the availability of more energy and nutrients for high performance and homeostatic pathways.

We have investigated the microstructure, the quasistatic and high-rate mechanical properties of magnesium (Mg)-based metal-matrix composites (MMCs) reinforced with nanoparticles, also termed as metal-matrix nanocomposites (MMNCs), in this case reinforced with nanoparticles of β-phase silicon carbide (β-SiC) the volume fraction ranging from 5 to 15 vol%. The yield and the ultimate strength increase with reinforcement volume fraction up to 10 vol% nanoparticles. MMCs with micrometer-sized SiC particles have higher yield strength than their MMNC counterparts, whereas the ultimate strength shows the opposing trend, suggesting greater strain hardening in the MMNCs. Transmission electron microscopy shows that the average interparticle distance decreases with increasing SiC vol%. Recrystallization was reported as completed during sintering at 575 °C [R.D. Doherty et al., Mater. Sci. Eng. A, 238, 219 (1997)], but dislocations might be generated due to thermal expansion mismatch of Mg/SiC during cooling. The majority of Mg-grains below 20 nm remain around the nanoparticles. As such a reverse volume fraction effect takes place in 15 vol% nanoparticle-reinforced MMNCs, which off sets the strengthening advantage induced by the nanoparticles.

Porcine circovirus type 2 (PCV2) is associated with various diseases that impose a significant economic burden on the swine industry. We hypothesised that nutritional supplementation with proline to enhance the immune response might be a useful prophylactic measure against PCV2 infection. To test this hypothesis, in the present study, we measured clinical data, including blood parameters, serum cytokine profile, PCV2 virus load in organs and serum, and microscopic lesions in the lung, liver and spleen, in both PCV2-infected pregnant and non-pregnant mice. Dietary supplementation with proline had no effect (P>0·05) on abortion rates in PCV2-infected pregnant mice, although a numerically lower abortion rate (22·2 v. 44·4 %) was observed compared with the control. Dietary supplementation with proline significantly increased serum C-reactive protein levels (P= 0·03) in PCV2-infected pregnant mice, and increased serum TNF-α levels (P= 0·01), leucocytes (P< 0·05), lymphocytes (P< 0·05) and neutrophilic granulocytes (P< 0·05) in PCV2-infected non-pregnant mice. Meanwhile, dietary proline significantly (P< 0·05) decreased the PCV2 virus load in the lung. Furthermore, mice in the dietary proline group showed a significant (P< 0·01) decrease in microscopic lesion scores in the lung, liver and spleen compared with those in the alanine group. Collectively, dietary proline supplementation confers a functional role in PCV2-infected mice.

The present study was conducted to evaluate the immune-enhancing effects of dietary l-glutamine supplementation in porcine circovirus type 2 (PCV2)-infected mice, and to examine the clearance effects of glutamine against PCV2 in experimentally infected mice. A total of sixty Kunming female mice were infected with PCV2 at a dose of 100 TCID50 (50 % tissue culture infection dose) by intraperitoneal injection after 2 weeks of dietary l-glutamine supplementation or l-alanine supplementation (as the control (isonitrogenous) group). The measured variables on 3rd, 5th, 7th, 9th and 11th d post-infection (dpi) included: (1) PCV2 virus loaded in the liver, spleen, heart, lung, kidney, ovary and serum was determined by real-time PCR; (2) IL-2, IL-6, IL-10, interferon (IFN)-α, IFN-γ and C-reactive protein levels in serum were measured by ELISA; (3) serum total superoxide dismutase activity was measured spectrophotometrically at 550 nm absorbance. Dietary l-glutamine supplementation significantly increased serum IL-2 levels on the 3rd (P< 0·01), 5th (P< 0·01), 7th (P< 0·05) and 9th dpi, significantly (P< 0·05) increased serum IL-6 levels on 3rd dpi, significantly (P< 0·05) increased serum IFN-γ levels on the 9th and 11th dpi and significantly decreased (P< 0·01) serum IL-10 levels on the 9th and 11th dpi, compared with those in the control group. Meanwhile, the PCV2 virus genome was detected sporadically throughout the experimental period in both groups. Taken together, the present results suggest that dietary l-glutamine supplementation enhances immune function in PCV2-infected mice.

Intestinal amino acid (AA) transport is critical for the supply of AA to other tissues. Few studies regarding AA intestinal transport systems during the period from postnatal intense development of piglets until weaning are available. In the present study, we measured the intestinal expression of b0,+AT according to developmental stage using the suckling Huanjiang piglet model, and documented the effect of intra-uterine growth restriction (IUGR) on such expression using real-time PCR and Western blot analysis. Suckling piglets that recovered after IUGR and those with normal body weights (NBW) were used after birth or at 7, 14 and 21 d of age. Blood samples were used for the measurement of plasma AA concentrations, and the jejunum was collected for the measurement of b0,+AT expression. In NBW piglets, b0,+AT expression was markedly decreased from days 0 to 21 (P< 0·01) and remained at a low level during all the suckling periods. In IUGR piglets, there was a marked decrease in b0,+AT expression at birth, which remained lower, when compared with NBW piglets, during the suckling period. These results coincided with decreased plasma arginine concentration at birth and decreased lysine concentration in 21-d-old piglets (P< 0·05). It is concluded that the high expression of b0,+AT at birth decreases during the suckling period, and that IUGR is associated with decreased expression of this apical AA transporter. The possible causal relationship between decreased b0,+AT expression and lower body weight of IUGR piglets in the suckling period is discussed.

The present study was conducted to determine the adjuvant effect of arginine in mice immunised with inactivated vaccine. Mice immunised with an inactivated Pasteurella multocida vaccine and fed diets supplemented with 0·2 % (vaccine-0·2 %) or 0·5 % (vaccine-0·5 %) arginine exhibited 100 % protection from a challenge with P. multocida serotype A (CQ2) at a dose of 4·4 × 105 colony-forming units (2LD50; median lethal dose), when compared with mice receiving no arginine supplementation. Meanwhile, antibody titres in the vaccine-0·2 % arginine group were much higher than those in the vaccine-oil adjuvant group before challenge and at 36 h post-infection. Furthermore, immunisation with the inactivated vaccine and dietary supplementation with 0·2 % arginine increased serum levels of glutathione peroxidase, in comparison with immunisation with the inactivated vaccine and an oil adjuvant. Collectively, dietary arginine supplementation confers an immunostimulatory effect in mice immunised with the inactivated P. multocida vaccine. The present results also indicate that optimal supplemental doses of arginine are 0·2–0·5 % in the mouse model.

The present study determined whether α-ketoglutarate (AKG) might affect the expression of AMP-activated protein kinase (AMPK) and energy status in the intestinal mucosa of piglets challenged with Escherichia coli lipopolysaccharide (LPS). A total of eighteen piglets (weaned at 21 d of age) were allocated to one of three treatments: (1) non-challenged (control); (2) LPS-challenged (LPS); (3) LPS+1 % AKG (LPS+AKG). Piglets in the control and LPS groups were fed a maize- and soyabean meal-based diet, and the LPS+AKG group was fed the basal diet supplemented with 1 % AKG. On days 10, 12, 14 and 16 of the trial, piglets in the LPS and LPS+AKG groups were challenged with LPS (80 μg/kg body weight), whereas piglets in the control group received the same volume of sterile saline. Pigs were euthanised 24 h after the last administration of LPS or saline to obtain intestinal mucosae for biochemical analysis. Compared with the control group, LPS administration decreased (P < 0·05) the oxidation of AKG, oleic acid, glutamine and glucose in enterocytes, decreased concentrations of ATP in the duodenal and jejunal mucosae and decreased adenylate energy charge (AMP:ATP ratio) in the jejunal and ileal mucosae. Additionally, LPS treatment reduced (P < 0·05) mucosal concentrations of phosphorylated AMPK in the jejunum and ileum as well as acetyl-CoA carboxylase in all segments of the small intestine. The adverse effects of LPS were reversed by AKG. Collectively, these results indicate that dietary supplementation with 1 % AKG beneficially modulates the AMPK signalling pathway to improve energy status in the small intestine of LPS-challenged piglets.

The present study was conducted to investigate the effect of digestion rate of dietary starch on postprandial systemic circulating glucose, insulin and lipid profiles, and the activity and gene expression of lipid metabolism-related enzymes in weaned pigs. A total of twenty-four weaned pigs, surgically fitted with a catheter in the jugular vein, were randomly assigned to three dietary treatment groups, representing the high digestion rate starch (HDRS) group, the moderate-digestion rate starch (MDRS) group and the low-digestion rate starch (LDRS) group. The amylopectin:amylose ratios in the diets of each group were 27·6:1, 27·6:8·5 and 1:27·6, respectively. The serum concentrations of glucose, TAG, total cholesterol, LDL-cholesterol and HDL-cholesterol in the HDRS group were increased to the peak point at postprandial 1·5, 2·5, 2·5, 1·5 and 1·5 h, those in the MDRS group were at postprandial 2·5, 3·5, 3·5, 3·5 and 3·5 h and those in the LDRS group were at postprandial 2·5, 3·5, 3·5, 1·5 and 3·5 h, respectively. The serum concentration of insulin in the HDRS group was higher (P < 0·05) than those in the MDRS group, and those in the MDRS group was also higher (P < 0·05) than those in the LDRS group at postprandial 0·5, 1·5 and 2·5 h, respectively. The serum concentrations of acetate, propionate and butyrate in the HDRS group were higher (P < 0·05) than those in the MDRS group, and those in the MDRS group were higher (P < 0·05) than in the LDRS group in each feeding cycle, in turn, respectively. The activity of fatty acid synthase (FAS) in the liver and abdominal adipose tissues, that of acetyl CoA carboxylase (ACC) in the myocardium and interscapular brown adipose tissues and that of the ATP-citrate lyase (ATP-CL) in the liver and interscapular brown adipose tissues in pigs of the HDRS group were higher (P < 0·05) than that of the MDRS group. The mRNA levels of FAS in the myocardium, liver and interscapular brown adipose tissues of pigs in the HDRS group were higher (P < 0·05) than those of the MDRS group. The activities and mRNA levels of FAS, ACC and ATP-CL in the myocardium, liver, abdominal and interscapular brown adipose tissues of the HDRS group were higher than those of the LDRS group. We conclude that the digestion rate of dietary starch affected not only the postprandial systemic circulating levels of glucose and insulin but also the lipid metabolism in weaned pigs. Dietary starch with higher digestion rate produces higher blood glucose and insulin response, ameliorates the blood lipid profiles and up-regulates the activity and gene expression profile of lipid metabolism-related genes in weaned pigs.

Oral administration of l-arginine has been reported to prevent gut disease in human infants. However, little is known about the effects of dietary arginine supplementation on intestinal development of weaned piglets. In the present study, twenty 21-d-old castrated piglets with 5·3 (sem 0·13) kg body weight (BW) were weaned from sows, individually housed and randomly assigned to one of the two maize- and soyabean meal-based diets supplemented with 0 or 1 % l-arginine. After consuming the diets for 7 d, six pigs were randomly selected from each group to obtain various tissues. Compared with control pigs, dietary supplementation with 1 % l-arginine did not affect feed intake but enhanced (P < 0·05) the relative weight of the small intestine (+33 %), daily BW gain (+38 %) and feed efficiency (+28 %). The villus height of the duodenum, jejunum and ileum in arginine-supplemented piglets was 21, 28 and 25 % greater (P < 0·05) than in the non-supplemented control group. Arginine supplementation increased (P < 0·05) protein levels for vascular endothelial growth factor (VEGF) in duodenal, jejunal and ileal mucosae by 14, 39 and 35 %, respectively. Compared with the control group, dietary supplementation with 1 % l-arginine increased (P < 0·05) plasma concentrations of arginine and insulin (+36 %), and decreased (P < 0·05) plasma concentrations of cortisol ( − 33 %), NH3 ( − 21 %) and urea ( − 19 %). These results indicate that arginine supplementation enhances intestinal growth, development and expression of VEGF in early-weaned pigs fed a maize- and soyabean meal-based diet. The findings may have important implications for neonatal pigs under stressful or diseased conditions.

The present study was conducted to evaluate the in vitro and in vivo digestibility of dietary starch and its digestive behaviour on the systemic circulating amino acids (AA) in weaned pigs. Eighteen weanling pigs surgically fitted with a catheter in the jugular vein were randomly assigned to three dietary treatment groups. Sticky rice starch (SRS) was hydrolysed more quickly in vitro (P < 0·05) than maize starch (MS) and resistant starch (RS), and was almost completely hydrolysed within 4 h. The in vivo digestibility of dietary starch in different segments of the small intestine was significantly different. SRS was digested (81·9 %; P < 0·05) in the anterior jejunum, but not more than half of the MS and RS was digested in the same segment of the small intestine. The digestibilities of isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, valine, alanine, aspartate and serine in the SRS group were higher than in the MS group (P < 0·05), and all nutritionally indispensable and dispensable AA in the SRS group were higher when compared with those in the RS group (P < 0·05). The serum concentrations of nutritionally indispensable AA, proline and serine in the three groups were increased to a peak point within 1·5 h postprandially then decreased gradually; however, the time that serum concentrations of alanine, aspartate, glutamate and glycine in each group increased to a peak point was different. The concentrations of nutritionally indispensable AA, including arginine, cystine, histidine, isoleucine, leucine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine at 09.30 hours and arginine, cystine, histidine, isoleucine, methionine, phenylalanine, threonine, tryptophan, tyrosine and valine at 13.30 hours in the SRS group were higher than in the MS group (P < 0·05); all nutritionally indispensable AA in the SRS group were higher than in the RS group at 09.30 and 13.30 hours (P < 0·05), respectively. We conclude that dietary starches digested rapidly in vitro have higher digestibility in the anterior small intestine of pigs. Diets containing rapidly digestible starch ameliorate the digestive and absorptive function and regulate AA metabolism to beneficially increase the entry of dietary AA into the systemic circulation in pigs.

Lactoferrin has antimicrobial activity associated with peptide fragments lactoferricin (LFC) and lactoferrampin (LFA) released on digestion. These two fragments have been expressed in Photorhabdus luminescens as a fusion peptide linked to protein cipB. The construct cipB–LFC–LFA was tested as an alternative to antimicrobial growth promoters in pig production. Sixty piglets with an average live body weight of 5·42 (sem 0·59) kg were challenged with enterotoxigenic Escherichia coli and randomly assigned to four treatment groups fed a maize–soyabean meal diet containing either no addition (C), cipB at 100 mg/kg (C+B), cipB–LFC–LFA at 100 mg/kg (C+L) or colistin sulfate at 100 mg/kg (C+CS) for 3 weeks. Compared with C, dietary supplementation with C+L for 3 weeks increased daily weight gain by 21 %, increased recovery from diarrhoea, enhanced serum glutathione peroxidase (GPx), peroxidase (POD) and total antioxidant content (T-AOC), liver GPx, POD, superoxide dismutase and T-AOC, Fe, total Fe-binding capacity, IgA, IgG and IgM levels (P < 0·05), decreased the concentration of E. coli in the ileum, caecum and colon (P < 0·05), increased the concentration of lactobacilli and bifidobacteria in the ileum, caecum and colon (P < 0·05), and promoted development of the villus–crypt architecture of the small intestine. Growth performance was similar between C+L- and C+CS-supplemented pigs. The present results indicate that LFC–LFA is an effective alternative to the feed antibiotic CS for enhancing growth performance in piglets weaned at age 21 d.

This study evaluated whether arginine (Arg) supplementation could attenuate gut injury induced by Escherichia coli lipopolysaccharide (LPS) challenge through an anti-inflammatory role in weaned pigs. Pigs were allotted to four treatments including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS+0·5 % Arg; (4) LPS+1·0 % Arg. On day 16, pigs were injected with LPS or sterile saline. At 6 h post-injection, pigs were killed for evaluation of small intestinal morphology and intestinal gene expression. Within 48 h of challenge, 0·5 % Arg alleviated the weight loss induced by LPS challenge (P = 0·025). In all three intestinal segments, 0·5 or 1·0 % Arg mitigated intestinal morphology impairment (e.g. lower villus height and higher crypt depth) induced by LPS challenge (P < 0·05), and alleviated the decrease of crypt cell proliferation and the increase of villus cell apoptosis after LPS challenge (P < 0·01). The 0·5 % Arg prevented the elevation of jejunal IL-6 mRNA abundance (P = 0·082), and jejunal (P = 0·030) and ileal (P = 0·039) TNF-α mRNA abundance induced by LPS challenge. The 1·0 % Arg alleviated the elevation of jejunal IL-6 mRNA abundance (P = 0·053) and jejunal TNF-α mRNA abundance (P = 0·003) induced by LPS challenge. The 0·5 % Arg increased PPARγ mRNA abundance in all three intestinal segments (P < 0·10), and 1·0 % Arg increased duodenal PPARγ mRNA abundance (P = 0·094). These results indicate that Arg supplementation has beneficial effects in alleviating gut mucosal injury induced by LPS challenge. Additionally, it is possible that the protective effects of Arg on the intestine are associated with decreasing the expression of intestinal pro-inflammatory cytokines through activating PPARγ expression.