The Expression of Zinc Transporters Changed in the Intestine of Weaned Pigs Exposed to Zinc Chitosan Chelate

This study was conducted to investigate the effect of zinc chitosan chelate (CS-Zn) on zinc transporter expression and content of tissue zinc in weaned piglets. A total of 90 weaned pigs (Duroc × Landrace × Yorkshire) were randomly allocated to treatment groups with supplementation of 100 mg/kg zinc as ZnSO₄, 100 mg/kg zinc as mixture of ZnSO₄ and chitosan, or 100 mg/kg zinc as CS-Zn, respectively. After 30 days of trial, 18 piglets (six pigs per treatment) were killed and the samples of duodenal mucosa were taken for analysis of zinc transporter mRNA expressions and protein abundance. The results show that CS-Zn more effectively increases (p < 0.05) the average daily gain (ADG) and serum zinc concentration. Zinc concentration in the liver and kidney did not differ between treatments. The mRNA expressions of ZnT1, ZIP4, and ZIP5 in CS-Zn treatment were all upregulated (p < 0.05) than ZnSO₄ or mixture of ZnSO₄ and chitosan groups. ZnT1 abundance was greater (p < 0.05) with CS-Zn as compared with ZnSO₄ and mixture of ZnSO4 and chitosan treatments, whereas ZIP4 and ZIP5 abundance was higher (p < 0.05) in ZnSO4 group. The results indicate that CS-Zn is more effective in serum zinc accumulation, and it might regulate zinc homeostasis by affecting zinc transporter mRNA expression and absorption mechanism might be different with ZnSO_4.

Changes in the diversity and composition of gut microbiota of weaned piglets after oral administration of Lactobacillus or an antibiotic

The gut microbiota plays important roles in the health and well-being of animals, and high-throughput sequencing facilitates exploration of microbial populations in the animal gut. However, previous studies have focused on fecal samples instead of the gastrointestinal tract. In this study, we compared the microbiota diversity and composition of intestinal contents of weaned piglets treated with Lactobacillus reuteri or chlortetracycline (aureomycin) using high-throughput sequencing. Nine weaned piglets were randomly divided into three groups and supplemented with L. reuteri, chlortetracycline, or saline for 10 days, and then the contents of three intestinal segments (jejunum, colon, and cecum) were obtained and used for sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The microbiota diversity and composition in the jejunum were different from those in the colon and cecum among the three treatments. In the jejunum, treatment with L. reuteri increased the species richness of the microbiota, as indicated by the ACE and Chao1 indexes, compared with the chlortetracycline group, in which several taxa were eliminated. In the colon and cecum, relative abundances of the phylum Firmicutes and the genus Prevotella were higher in the chlortetracycline group than in the other groups. Distances between clustered samples revealed that the L. reuteri group was closer to the chlortetracycline group than the control group for jejunum samples, while colon and cecum samples of the L. reuteri group were clustered with those of the control group. This study provides fundamental knowledge for future studies such as the development of alternatives to antibiotics.

Effects of Brevibacillus brevis FJAT-1501-BPA on growth performance, faecal microflora, faecal enzyme activities and blood parameters of weaned piglets

A feeding expriment was performed to investigate the effects of dietary supplementation with Brevibacillus brevis FJAT-1501-BPA fermentation on the growth performance, faecal microflora, faecal enzyme activities and blood parameters of weaned piglets. A total of 150 weaned piglets were randomly assigned to different treatments groups, which were fed the same basic diet supplemented with 10, 1, 0.1, 0.01 and 0 % B. brevis FJAT-1501-BPA fermentation. The results showed that a diet supplemented with 10 % B. brevis FJAT-1501-BPA fermentation could significantly increase the final body weight (P < 0.05) and decrease feed to gain ratio, which was 37.1 % lower than that of the control group. The addition of B. brevis FJAT-1501-BPA exhibited a trend of reducing the contents of the Escherichia coli, Lactobacillus and Salmonella compared with the control. During the 35 day experimental period, cellulase and protease activities were significantly increased by the dietary inclusion of the B. brevis FJAT-1501-BPA fermentation (P < 0.05). The cellulase activity for piglets fed diet containing 1 % B. brevis FJAT-1501-BPA fermentation, 21.8 U/g, was highest among the different treatments. The protease activity for piglets fed diet containing 10 % B. brevis FJAT-1501-BPA fermentation, 50.4 U/g, was highest among the different treatments. The amylase and hemicellulase activities for piglets fed diet containing 10 % B. brevis FJAT-1501-BPA fermentation were significantly higher than those on the control diet and other treatments (P < 0.05). Moreover, usage of feed dietary supplementation with B. brevis FJAT-1501-BPA had positive effects on levels of enzymes and minerals in blood. The alkaline phosphatase, alanine aminotransferase, Fe and Mg concentrations for weaned piglets fed diet containing B. brevis FJAT-1501-BPA fermentation were significantly higher than for those on the control diet (P < 0.05). Furthermore, concentration of IgG in serum was higher in weaned piglets fed diet containing 1 % B. brevis FJAT-1501-BPA fermentation compared to other treatments. These results indicated that feeding with B. brevis FJAT-1501-BPA has the potential to improve growth performance, faecal microflora, faecal enzyme activities and blood parameters of weaned piglets.

Effects of bamboo vinegar powder on growth performance and mRNA expression levels of interleukin-10, interleukin-22, and interleukin-25 in immune organs of weaned piglets

The aim of this study was to explore the effects of bamboo vinegar powder on growth performance, diarrhea situation and mRNA expression levels of cytokines i.e., interleukin-10 (IL-10), interleukin-22 (IL-22), and interleukin-25 (IL-25) in immune organs of weaned piglets, and to accumulate theoretical data for the application of bamboo vinegar powder in weaned piglet production. Forty-five crossbred (Duroc × Landrace × Yorkshire, all male) weaned piglets with similar body weight (6.74 ± 0.17 kg) at 31 days of age were randomly assigned to 5 treatments with 3 replicates per treatment and 3 piglets in each replicate. The five treatments were as follows: CON (a basal diet), ANT (the basal diet + 0.12% antibiotics), BV1 (the basal diet + 0.1% bamboo vinegar powder), BV5 (the basal diet + 0.5% bamboo vinegar powder), BV10 (the basal diet + 1.0% bamboo vinegar powder). This experiment lasted 35 days. The growth performance and diarrhea situation were recorded. The relative mRNA expression levels of IL-10, IL-22 and IL-25 in liver, spleen, duodenum and mesenteric lymph nodes were detected by real-time PCR. Feed: gain of BV5 was significantly lower than that of CON (P < 0.05). In comparison with CON, diarrhea rate and diarrhea index of BV1 and BV5 all tended to decrease (P < 0.1). Compared with CON, mRNA expression level of IL-10 in liver of ANT tended to be lower (P < 0.1) and these of BV1, BV5 and BV10 were significantly reduced (P < 0.05). The mRNA expression levels of IL-10 in duodenum of ANT, BV1, BV5 and BV10 were all lower than those of CON, of which BV10 had significantly decreased IL-10 mRNA expression in duodenum (P < 0.05). The mRNA expression levels of IL-22 in duodenum of ANT, BV1, BV5 and BV10 all tended to be inhibited compared with CON (P < 0.1). With the increase of bamboo vinegar powder dosage, mRNA expression levels of IL-25 in spleen and mesenteric lymph nodes of BV1, BV5 and BV10 tended to be up-regulated. Overall, bamboo vinegar powder could improve growth performance, and regulate mRNA expression levels of IL-10, IL-22 and IL-25 in immune organs of weaned piglets. The dosage at 0.5% showed optimum effects.

The prolonged effect of glucagon-like peptide 2 pretreatment on growth performance and intestinal development of weaned piglets

BACKGROUND

Glucagon-like peptide 2 (GLP-2) is a potent epithelium-specific intestinal growth factor. The aim of this study was to demonstrate the prolonged effect of GLP-2 on the growth performance of weaned piglets. Forty piglets weaned at the age of 28 d with an average BW of 6.8 ± 0.4 kg were assigned to four treatments: (i) non-challenged control; (ii) LPS-challenged control; (iii) LPS + low GLP-2; and (iv) LPS + high GLP-2. Piglets in groups (i), (ii), and (iv) were s.c. injected with PBS supplemented with human [Gly2]GLP-21-34 at doses of 0, 2 and 10 nmol/kg BW per day for seven consecutive days. BW, gain:feed ratio (G:F), and plasma GLP-2 levels were determined on d 0, 7, and 14 after weaning. Piglets were challenged with i.p. administration of Escherichia coli lipopolysaccharide (LPS) at a dose of 100 μg/kg on d 14 to induce intestinal damage. Twenty-four hours later, intestinal tract samples were collected to assess intestinal morphology and quantify enzyme activity.

RESULTS

Plasma GLP-2 levels decreased after weaning, but in the high GLP-2 group, plasma GLP-2 was maintained on d 7 and even increased to a level higher than the preweaning level on d 14 (P < 0.05). High GLP-2 treatment significantly increased the duodenal, jejunal and ileal weight, as well as the gross weight of the small intestine (SI), and the SI weight index (P < 0.05). LPS caused villous atrophy and disrupted intestinal morphology in the duodenum, jejunum and ileum. GLP-2 also significantly increased the villus height and the villus height/crypt depth ratio (VCR) of the duodenum, jejunum, and ileum (P < 0.05). Histological examination revealed that in GLP-2-treated groups, the integrity of the villus was maintained, and the villus was protected against LPS-induced damage. GLP-2 significantly increased the activity of alkaline phosphatase (AKP), γ-glutamyltranspeptidase (γ-GT), and pancreatic lipase in the duodenum and jejunum (P < 0.05). GLP-2 treatment also significantly increased the average daily gain (ADG) and G:F of piglets at 0 to 7, 7 to 14, as well as 0 to14 d (P < 0.05), resulting in a significant increase of final BW in high GLP-2 pigs (P = 0.016).

CONCLUSIONS

Exogenous GLP-2 improved the growth of weaned piglets and protected them against LPS-induced intestinal damage. These effects may be due to the ability of GLP-2 to promote the secretion of endogenous GLP-2 to stimulate the small intestinal development.

Effects of dietary supplementation with epidermal growth factor-expressing Saccharomyces cerevisiae on duodenal development in weaned piglets

The aim of the present study was to assess the effects of dietary supplementation with epidermal growth factor (EGF)-expressing Saccharomyces cerevisiae on duodenal development in weaned piglets. In total, forty piglets weaned at 21-26 d of age were assigned to one of the five groups that were provided basic diet (control group) or diet supplemented with S. cerevisiae expressing either empty-vector (INVSc1(EV) group), tagged EGF (T-EGF) (INVSc1-TE(-) group), extracellular EGF (EE-EGF) (INVSc1-EE(+) group) or intracellular EGF (IE-EGF) (INVSc1-IE(+) group). All treatments were delivered as 60·00 μg/kg body weight EGF/d. On 0, 7, 14 and 21 d, eight piglets per treatment were sacrificed to analyse the morphology, activities and mRNA expressions of digestive enzymes, as well as Ig levels (IgA, IgM, IgG) in duodenal mucosa. The results showed significant improvement on 7, 14 and 21 d, with respect to average daily gain (P<0·05), mucosa morphology (villus height and crypt depth) (P<0·05), Ig levels (P<0·01), activities and mRNA expressions of digestive enzymes (creatine kinase, alkaline phosphatase, lactate dehydrogenase and sucrase) (P<0·05) and the mRNA expression of EGF-receptor (P<0·01) in NVSc1-TE(-), INVSc1-EE(+) and INVSc1-IE(+) groups compared with control and INVSc1(EV) groups. In addition, a trend was observed in which the INVSc1-IE(+) group showed an improvement in Ig levels (0·05<P<0·10), mRNA expressions of digestive enzymes and EGF-receptor (P<0·05) compared with NVSc1-TE(-) and INVSc1-EE(+) groups. These results indicate that supplementing recombinant EGF-expressing S. cerevisiae to the diet of weaned piglets enhanced duodenal development. Moreover, biological activity (Ig levels, mRNA expressions of digestive enzymes and EGF-receptor) of IE-EGF was better than either EE-EGF or T-EGF.

Aspartate attenuates intestinal injury and inhibits TLR4 and NODs/NF-κB and p38 signaling in weaned pigs after LPS challenge

PURPOSE

This study was conducted to investigate whether aspartate (Asp) could alleviate Escherichia coli lipopolysaccharide (LPS)-induced intestinal injury by modulating intestine inflammatory response.

METHODS

Twenty-four weaned piglets were divided into four treatments: (1) non-challenged control; (2) LPS-challenged control; (3) LPS + 0.5 % Asp; and (4) LPS + 1.0 % Asp. After feeding with control, 0.5 or 1.0 % Asp-supplemented diets for 21 days, pigs were injected intraperitoneally with saline or LPS. At 4 h postinjection, blood and intestine samples were obtained.

RESULTS

Asp supplementation to LPS-challenged pigs improved intestinal morphology, indicated by higher jejunal and ileal villus height/crypt depth ratio and lower ileal crypt depth linearly or quadratically. Asp also improved intestinal barrier function, indicated by increased jejunal and ileal diamine oxidase activities as well as enhanced protein expression of jejunal claudin-1 linearly or quadratically. In addition, Asp decreased plasma, jejunal and ileal tumor necrosis factor-α concentration and ileal caspase-3 protein expression linearly and quadratically. Moreover, Asp down-regulated the mRNA expression of toll-like receptor 4 (TLR4) and nucleotide-binding oligomerization domain protein (NOD) signaling-related genes, nuclear factor-κB (NF-κB) p65 and p38, decreased phosphorylation of jejunal p38, and increased phosphorylation of ileal extracellular signal-related kinase 1/2 linearly or quadratically. Finally, Asp increased mRNA expressions of TLR4 and NOD signaling negative regulators including radioprotective 105, suppressor of cytokine signaling 1, toll-interacting protein, Erbb2 interacting protein and centaurin β1 linearly or quadratically.

CONCLUSIONS

These results indicate that Asp supplementation is associated with inhibition of TLR4 and NODs/NF-κB and p38 signaling pathways and concomitant improvement of intestinal integrity under an inflammatory condition.

Asparagine attenuates intestinal injury, improves energy status and inhibits AMP-activated protein kinase signalling pathways in weaned piglets challenged with Escherichia coli lipopolysaccharide

The intestine requires a high amount of energy to maintain its health and function; thus, energy deficits in intestinal mucosa may lead to intestinal damage. Asparagine (Asn) is a precursor for many other amino acids such as aspartate, glutamine and glutamate, which can be used to supply energy to enterocytes. In the present study, we hypothesise that dietary supplementation of Asn could alleviate bacterial lipopolysaccharide (LPS)-induced intestinal injury via improvement of intestinal energy status. A total of twenty-four weaned piglets were assigned to one of four treatments: (1) non-challenged control; (2) LPS+0 % Asn; (3) LPS+0·5 % Asn; (4) LPS+1·0 % Asn. On day 19, piglets were injected with LPS or saline. At 24 h post-injection, piglets were slaughtered and intestinal samples were collected. Asn supplementation improved intestinal morphology, indicated by higher villus height and villus height:crypt depth ratio, and lower crypt depth. Asn supplementation also increased the ratios of RNA:DNA and protein:DNA as well as disaccharidase activities in intestinal mucosa. In addition, Asn supplementation attenuated bacterial LPS-induced intestinal energy deficits, indicated by increased ATP and adenylate energy charge levels, and decreased AMP:ATP ratio. Moreover, Asn administration increased the activities of key enzymes involved in the tricarboxylic acid cycle, including citrate synthase, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase complex. Finally, Asn administration decreased the mRNA abundance of intestinal AMP-activated protein kinase-α1 (AMPKα1), AMPKα2, silent information regulator 1 (SIRT1) and PPARγ coactivator-1α (PGC1α), and reduced intestinal AMPKα phosphorylation. Collectively, these results indicate that Asn supplementation alleviates bacterial LPS-induced intestinal injury by modulating the AMPK signalling pathway and improving energy status.

Effect of dietary supplementation with protease on growth performance, nutrient digestibility, intestinal morphology, digestive enzymes and gene expression of weaned piglets

This study was conducted to investigate the effect of dietary protease supplementation on the growth performance, nutrient digestibility, intestinal morphology, digestive enzymes and gene expression in weaned piglets. A total of 300 weaned piglets (21 days of age Duroc × Large White × Landrace; initial BW = 6.27 ± 0.45 kg) were randomly divided into 5 groups. The 5 diets were: 1) positive control diet (PC), 2) negative control diet (NC), and 3) protease supplementations, which were 100, 200, and 300 mg per kg NC diet. Results indicated that final BW, ADG, ADFI, crude protein digestibility, enzyme activities of stomach pepsin, pancreatic amylase and trypsin, plasma total protein, and intestinal villus height were higher for the PC diet and the supplementations of 200 and 300 mg protease per kg NC diet than for the NC diet (P < 0.05). Supplementations of 200 and 300 mg protease per kg NC diet significantly increased the ratio of villus height to crypt depth (VH:CD) of duodenum, jejunum and ileum compared with NC diet (P < 0.05). Feed to gain ratio, diarrhea index, blood urea nitrogen, and diamine oxidase were lower for the PC diet and supplementations of 200 and 300 mg protease per kg NC diet than for the NC diet (P < 0.05). Piglets fed the PC diet had a higher peptide transporter 1 (PepT1) mRNA abundance in duodenum than piglets fed the NC diet (P < 0.05), and supplementations of 100, 200 and 300 mg protease per kg NC diet increased the PepT1 mRNA abundance in duodenum (P < 0.05) comparing with the NC diet. Piglets fed the PC diet had a higher b0,+AT mRNA abundance in jejunum than piglets fed the NC diet (P < 0.05), and supplementations of 200 and 300 mg protease per kg NC diet increased the b0,+AT mRNA abundance in jejunum and ileum comparing with the NC diet (P < 0.05). In summary, dietary protease supplementation increases growth performance in weaned piglets, which may contribute to the improvement of intestinal development, protein digestibility, nutrient transport efficiency, and health status of piglets when fed low digestible protein sources.

Effects of protein sources and levels in antibiotic-free diets on diarrhea, intestinal morphology, and expression of tight junctions in weaned piglets

This study examined effects of dietary protein sources and levels on intestinal health of 21 to 35 d-old weaned piglets fed antibiotics-free diets. A total of 150 weaned piglets (21 d of age) were allotted to 5 dietary treatment groups. Diets were formulated, based on corn-soybean meal, with different protein sources (fish meal and soy protein concentrate) to provide different dietary CP levels. Piglets within 5 dietary treatments were fed diets as follows, respectively: 1) control diet of 17% CP (control); 2) 19% CP diets formulated with more soy protein concentrate (SPC19); 3) fish meal (FM19); 4) 23.7% CP diets formulated with more soy protein concentrate (SPC23); 5) fish meal (FM23). The results showed that piglets from control group had higher ADG and lower incidence of diarrhea compared with those of other groups (P < 0.05). The incidence of diarrhea of piglets in FM19 group was lower than those from SPC23 group and FM23 group (P < 0.05). With the higher CP levels, villous height and villous height to crypt depth ratio of piglets in the duodenum and jejunum were decreased (P < 0.05), but crypt depth was increased (P < 0.05). Comparing control group and other groups, we found the expression of inflammatory cytokines interleukin-1β (IL-1β) and interferon-γ (IFN-γ) were increased (P < 0.05) in the jejunum and colon of piglets, as did cystic fibrosis transmembrane conductance regulators (CFTR) in the distal colon. The relative transcript abundance of Zonula occludens-1 (ZO-1) in the jejunum, and occludin in the jejunum and ileum of piglets fed 23.7% CP diets were reduced compared with those fed control diet (P < 0.05). In conclusion, the 17% CP diet without in-feed antibiotics helped improve growth performance and relief of diarrhea of 21 to 35 d-old weaned piglets. Dietary CP level, rather than its source (either fish meal or soy protein concentrate), has more significant impacts on the growth performance and intestinal health of 21 to 35 d-old weaned piglets when fed antibiotics-free diets.

Dietary soy isoflavone attenuated growth performance and intestinal barrier functions in weaned piglets challenged with lipopolysaccharide

This study was conducted to investigate the protective roles of soy isoflavone in weaned pigs challenged with lipopolysaccharide (LPS). A total of 72 weaned piglets (14 days of age) were randomly allotted into either 0 (control group) or 40 mg/kg soy isoflavone (ISO) supplementation group. On days 7 and 14, half of the pigs in each group were challenged with LPS. Soy isoflavone increased average daily gain (ADG) and average daily feed intake (ADFI) of piglets challenged with LPS at days 7-14 (P<0.05). The incidence of diarrhea and plasma concentrations of malondialdehyde (MDA) and endotoxin in piglets from LPS group were higher than those in control group (P<0.05). Soy isoflavone reduced the incidence of diarrhea and plasma concentrations of endotoxin in piglets challenged with LPS (P<0.05). LPS challenge decreased (P<0.05) mRNA abundances of β-defensin 2 (pBD-2), mucin (MUC-4), zona occludens 1 (ZO-1), and occludin in jejunal mucosa of piglets, and soy isoflavone upregulated (P<0.05) mRNA abundances of ZO-1 and occludin in jejunal mucosa of piglets challenged with LPS. The present results demonstrated that both p38 and TLR4 pathways in jejunal mucosa of piglets were activated by LPS challenge (P<0.05), and soy isoflavone reduced their activations (P<0.05). Collectively, our results suggested that supplementation of soy isoflavone could partly attenuate the barrier-damaged effects of LPS and improve the intestinal barrier function of weaned piglets, at least partially by inhibiting activations of p38 and TLR4 dependent pathways induced by LPS. This study provides a potential usage of soy isoflavone for alleviating intestinal barrier damages of neonates and piglets.

Asparagine attenuates hepatic injury caused by lipopolysaccharide in weaned piglets associated with modulation of Toll-like receptor 4 and nucleotide-binding oligomerisation domain protein signalling and their negative regulators

Pro-inflammatory cytokines play a key role in many models of hepatic damage. In addition, asparagine (Asn) plays an important role in immune function. We aimed to investigate whether Asn could attenuate lipopolysaccharide (LPS)-induced liver damage. Forty-eight castrated barrows were allotted to four groups including: (1) non-challenged control; (2) LPS-challenged control; (3) LPS + 0.5% Asn; and (4) LPS + 1.0% Asn. After 19 d feeding with control, 0.5 or 1.0% Asn diets, pigs were injected with LPS or saline. Blood and liver samples were obtained at 4 h (early stage) and 24 h (late stage) post-injection. Asn alleviated liver injury, indicated by reduced serum aspartate aminotransferase and alkaline phosphatase activities linearly and quadratically; it increased claudin-1 protein expression linearly and quadratically at 24 h, and less severe liver morphological impairment at 4 or 24 h. In addition, Asn decreased mRNA expression of TNF-α and heat shock protein 70 (HSP70) linearly and quadratically at 4 h; it increased TNF-α mRNA expression, and HSP70 protein expression linearly and quadratically at 24 h. Moreover, Asn increased inducible NO synthase activity linearly and quadratically. Finally, Asn down-regulated the mRNA expression of Toll-like receptor 4 (TLR4) signalling molecules (TLR4, IL-1 receptor-associated kinase 1 (IRAK1), TNF-α receptor-associated factor 6), nucleotide-binding oligomerisation domain protein (NOD) signalling molecules (NOD1, NOD2 and their adaptor molecule receptor-interacting serine/threonine-protein kinase 2 (RIPK2)), and NF-κB p65 linearly or quadratically at 4 h. Oppositely, Asn up-regulated mRNA expressions of TLR4 and NOD signalling molecules (TLR4, myeloid differentiation factor 88, IRAK1, NOD2 and RIPK2), and their negative regulators (radioprotective 105, single Ig IL-1R-related molecule, Erbb2 interacting protein and centaurin β1) linearly or quadratically at 24 h. These results indicate that, in early and late stages of LPS challenge, Asn improves liver integrity and exerts different regulatory effects on mRNA expression of TLR4 and NOD signalling molecules.

Effects of curcumin on growth performance, jejunal mucosal membrane integrity, morphology and immune status in weaned piglets challenged with enterotoxigenic Escherichia coli

The aim of this study was to evaluate the effect of dietary curcumin supplementation on growth performance and intestinal mucosal barrier function of weaned piglets. Fifty piglets, weaned at 21±2 days of age, were randomly allotted to five treatments for 21 days. The dietary treatments were the control (basal diet), and the basal diet supplemented with 50mg/kg quinocetone, or 200 mg/kg, 300 mg/kg or 400mg/kg curcumin. The piglets were housed in individual pens and orally challenged with enterotoxigenic Escherichia coli (ETEC) during the preliminary trial period. The jejunal morphology and histology analysis were detected under light microscope. The plasma D-lactate and diamine oxidase (DAO) were determined by using enzymatic spectrophotometric assay. Immunohistochemistry assays were used to examine secretory immunoglobulin (sIgA) protein expression. Real-time PCR was used to determine mRNA levels of cytokine and Toll-like receptor 4 (TLR4) in jejunal mucosa. The results showed that, compared with the control, dietary addition of 300 mg/kg or 400 mg/kg curcumin decreased (P<0.05) feed/gain ratio and crypt depth, improved (P<0.05) villus height and villus height:crypt depth ratio, reduced (P<0.05) plasma D-lactate and DAO activity, up-regulated the protein expression of sIgA (P<0.05), increased (P<0.05) the number of goblet cells (GCs) and reduced (P<0.05) the number of intraepithelial lymphocytes (IELs). The mRNA levels of interleukin 1β (IL-1β) and TLR4 and tumor necrosis factor α (TNF-α) were also decreased (P<0.05), but mRNA level of interleukin 10 (IL-10) was increased (P<0.05). There was no difference in the above parameters between the 300 mg/kg and 400 mg/kg curcumin groups. Pigs fed with 50 mg/kg quinocetone also decreased (P<0.05) feed/gain ratio, increased villus height:crypt depth ratio (P<0.05), and reduced (P<0.05) crypt depth and mRNA levels of TLR4. In conclusion, curcumin and the quinocetone have similar effects in improving piglet growth, but dietary addition of 300 mg/kg or 400 mg/kg curcumin was more effective than quinocetone in improving intestinal mucosal barrier integrity, morphology, and immune status of weaned pigs. This indicates that curcumin could be used as a potential feed additive replacing quinocetone in weaned piglets.

Intestinal microbiota diversity and expression of pattern recognition receptors in newly weaned piglets

This study evaluated the gastrointestinal microbial diversity and the expression of pattern recognition receptors (PRRs) of the small intestine during the first week post-weaning in newly weaned piglets. Sixteen piglets were sacrificed on days 0, 1, 4, and 7 post-weaning. Luminal contents from the stomach, ileum, and colon were collected to determine the microbiota diversity; intestinal mucosa from the ileum was collected to assess mRNA expression of PRRs, including toll-like receptors (TLRs) and NOD-like receptors (NLRs); sections of ileum were examined immunohistochemically to assess the immunoglobulin-secreting cells. The results showed that the number of denaturing gradient gel electrophoresis (DGGE) bands from the ileum and colon contents were significantly reduced in the d 4 post-weaning group. Biodiversity indexes (Shannon-Wiener index, richness index, and evenness index) were significantly decreased in the ileum of weaning groups. These indexes decreased in the colon of the d 4 post-weaning group. No significant differences were obtained in the stomach. With the exception of TLR5, the mRNA expressions of TLR2, TLR4, and TLR7 increased post-weaning. The mRNA expressions of NOD1 and NOD2 were significantly affected in the d 4 post-weaning group, and there were no significant differences in the d 1 or d 7 post-weaning groups. Analysis of the immunoglobulin-secreting (IgA, IgG, and IgM) cells showed that the ratio of each immunoglobulin was significantly higher on d 7 than d 0. The results revealed that microbial diversity was lower in the ileum and on d 4 post-weaning. Weaning significantly affected the expression of intestinal PRRs mainly on d 1 and d 4 post-weaning. The expression of specific PRRs was triggered by weaning to recognize distinctive microbiota and promote the development and maturation of the intestinal mucosal immunity.

The effect of dietary tryptophan levels on oxidative stress of liver induced by diquat in weaned piglets

Oxidative stress can induce abnormal tryptophan metabolism. The present study was mainly conducted to determine the effect of dietary tryptophan levels on oxidative stress in the liver of weaned pigs challenged by diquat. A total of 36 PIC piglets weaned at 21 days of age were randomly allotted to 1 of 3 diets containing dietary tryptophan levels of 0.18, 0.30, and 0.45% for 14 d. On day 8, the piglets were injected intraperitoneally with sterile 0.9% NaCl solution or diquat (10 mg/kg body weight). During the first 7 d of trial, increasing dietary tryptophan levels enhanced average daily gain (P = 0.09) and average daily feed intake (P = 0.08), and decreased the feed efficiency (P < 0.05) of piglets. The growth performance was decreased by diquat injection (P < 0.05). Diquat injection also decreased the activities of the superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the plasma and liver (P < 0.05), increased plasma malondialdehyde (MDA) (P < 0.05) and urea nitrogen (P < 0.05) concentrations, and enhanced MDA concentration (P = 0.09) and tryptophan 2,3-dioxygenase (TDO) activity (P = 0.07) in liver of piglets. Increasing dietary tryptophan levels could attenuate the effects of diquat injection on the MDA (P = 0.06) concentration and the activities of SOD (P = 0.09) and GPx (P = 0.05) of the liver, and plasma urea nitrogen (P = 0.06) concentration in the piglet. There was a synergistic role for increasing TDO activity in the liver between dietary tryptophan levels and diquat injection (P < 0.05). These results suggest that increasing dietary tryptophan levels could attenuate the oxidative stress of the liver in weaned piglets intraperitoneally injected with diquat via enhancing the antioxidant capacity.