Effects of dietary supplementation with l-arginine on the intestinal barrier function in finishing pigs with heat stress

Previous studies showed heat stress reduces body weight gain and feed intake associated with damaged intestinal barrier function, and l -arginine (L-Arg) enhanced intestinal barrier function in young animals under stress. The aim of this study was to evaluate effects of L-Arg on serum hormones, intestinal morphology, nutrients absorption and epithelial barrier functions in finishing pigs with heat stress. Forty-eight finishing pigs (Landrace) were balanced for sex and then randomly assigned to six groups: TN group, thermal neutral (22°C, ~80% humidity) with a basal diet; HS group, heat stress (cyclical 35°C for 12 hr and 22°C for 12 hr, ~80% humidity) with a basal diet; PF group, thermal neutral (22°C, ~80% humidity) and pair-fed with the HS; the TNA, HSA and PFA groups were the basal diet of TN group, HS group and PF group supplemented with 1% L-Arg. Results showed that HS decreased (p < .05) the thyroxine concentrations and increased (p < .05) the insulin concentrations in serum compared with the TN group, but 1% L-Arg had no significant effects on them. Both HS and PF significantly increased (p < .05) the mRNA expression of cationic amino acid transporters (CAT1 and CAT2) and decreased the mRNA expression of solute carrier family 5 member 10 (SGLT1) in the jejunum compared with the TN group. Compared with the TN group, HS reduced the expression of tight junction (TJ) protein zonula occluden-1 (ZO-1) and occludin, but PF only decreased ZO-1 expression in the jejunum. Results exhibited that dietary supplementation with 1% L-Arg improved the intestinal villous height, the ratio of villous height to crypt depth, and the expression of occludin and porcine beta-defensin 2 (pBD2) in the jejunum of intermittent heat-treated finishing pigs. In conclusion, dietary supplementation with 1% L-Arg could partly attenuate the intermittent heat-induced damages of intestinal morphology and epithelial barrier functions in finishing pigs.     

L-精氨酸对脂多糖刺激断奶仔猪肠黏膜免疫屏障的影响

本试验旨在研究L-精氨酸(L-Arg)对脂多糖(LPS)刺激仔猪肠黏膜免疫的影响。选用24头21日龄断奶仔猪,随机分为4个处理,即对照组(基础日粮)、LPS组(基础日粮+LPS)、0.5%Arg组(基础日粮添加0.5%Arg+LPS)、1.0%Arg组(基础日粮添加1.0%Arg+LPS)。结果表明:LPS刺激损伤小肠黏膜结构;Arg则有效阻止LPS应激导致的肠道损伤,维持肠黏膜结构的完整性;LPS刺激显著增加仔猪小肠肥大细胞数(P<0.01);1.0%Arg则减少肥大细胞数(P<0.05);LPS刺激降低回肠IgA分泌细胞、CD4+、CD8+阳性细胞数(P<0.05),而0.5%Arg则增加IgA分泌细胞、CD4+、CD8+阳性细胞数(P<0.05)。这表明LPS刺激可导致仔猪小肠黏膜结构受损,免疫屏障功能降低,而日粮添加精氨酸可有效阻止LPS对肠黏膜屏障的损伤,促进及改善肠黏膜结构及免疫屏障功能。     

4-Phenylbutyric acid accelerates rehabilitation of barrier function in IPEC-J2 cell monolayer model

As the first line of defence against pathogens and endotoxins crossing the intestine-blood barrier, the intestinal epithelial barrier plays a determinant role in pigs' health and growth. 4-Phenylbutyric acid (4-PBA), an aromatic fatty acid, was reported to benefit homeostasis of endoplasmic reticulum and protein synthesis. However, whether 4-PBA affects intestinal epithelial barrier function in pigs is unknown. This study aimed to explore the effects of 4-PBA on the intestinal barrier function, using in vitro models of well-differentiated intestinal porcine epithelial cell (IPEC-J2) monolayers in the transwell plates. Cell monolayers with or without 4-PBA (1.0 mmol/L) treatment were challenged with physical scratch, deoxynivalenol (DON, 2.0 μg/mL, 48 h), and lipopolysaccharide (LPS, 5.0 μg/mL, 48 h), respectively. Transepithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran (FD-4) permeability were measured to indicate barrier integrity and permeability. Real-time PCR and Western blot were conducted to determine relative gene and protein expressions of tight junction proteins. As expected, physical scratch, DON, and LPS challenges decreased TEER and increased FD-4 permeability. 4-PBA treatment accelerated cell mitigation and rehabilitation of the physical scratch-damaged intestinal epithelial barrier but did not alleviate DON or LPS induced barrier damage. However, once 48-h DON and LPS challenges were removed, rehabilitation of the epithelial barrier function of IPEC-J2 monolayer was accelerated by the 4-PBA treatment. Also, the relative gene and protein expressions of zonula occludens-1 (ZO-1), occludin, and claudin-1 were further upregulated by the 4-PBA treatment during the barrier rehabilitation. Taken together, 4-PBA accelerated the IPEC-J2 cell monolayer barrier recovering from physical scratch, DON-, and LPS-induced damage, via enhancing cell mitigation and expressions of tight junction proteins.     

Effect of chito-oligosaccharide on growth performance, intestinal barrier function, intestinal morphology and cecal microflora in weaned pigs

A total of 180 weanling pigs (21 ± 3 d of age; 5.98 ± 0.04 kg) were used to investigate the effect of chito-oligosaccharide (COS) on growth performance, intestinal barrier function, intestinal morphology, and cecal microflora. Based on initial BW, gender and litter, the pigs were given 5 treatments during a 14-d feeding experiment, including a basal diet (control), 3 diets with COS supplementation (200, 400, or 600 mg/kg), and a diet with colistin sulfate (CSE) supplementation (20 mg/kg). Six randomly selected pigs from each treatment were used to collect serum, duodenal, jejunal, ileal, and cecal samples on d 7 and 14 postweaning. From d 1 to 7 postweaning, pigs fed COS or CSE had greater ADG and ADFI compared with the control pigs. From d 1 to 14, diets with either 400 or 600 mg/kg COS, or 20 mg/kg CSE increased (P < 0.05) ADG and G:F compared with the control diet. No significant differences were observed in ADG, ADFI, and G:F between the pigs fed COS and CSE. Pigs fed either 400 or 600 mg/kg COS, or 20 mg/kg CSE had less (P < 0.05) diamine oxidase (DAO) in the serum, but greater concentration of (P < 0.05) DAO in jejunal mucosa, than the control pigs on d 7 postweaning. Treatments did not affect villous height and crypt depth of the duodenum, jejunum, or ileum. Pigs fed COS at 400 mg/kg had greater (P < 0.05) concentration of Bifidobacteria and Lactobacilli in the cecum than pigs fed the control diet and CSE diet on d 7 postweaning. Supplementation of COS or CSE decreased (P < 0.05) the population of cecal Staphylococcus aureus compared with the control diet on d 7 postweaning. The number of cecal Bifidobacteria in pigs fed 600 mg/kg COS was greater (P < 0.05) than that of pigs fed the control diet or CSE diet on d 14 postweaning. No significant differences were observed in Escherichia coli counts in the cecum among treatments. The present results indicate that dietary supplementation of COS at 400 or 600 mg/kg promotes growth performance and improves gut barrier function, increases the population of Bifidobacteria and Lactobacilli, and decreases S. aureus in the cecum of weanling pigs.     

Dietary supplementation of plant essential oil improves growth performance,intestinal morphology and health in weaned pigs

The present study was conducted to explore the effect of plant essential oil (PEO) on growth performance, intestinal morphology and health in weaned pigs. Twenty-four weaned pigs were assigned into four groups fed with a basal diet (CON) or basal diet containing PEO at a concentration of 50 (PEO50), 100 (PEO100) or 200 ppm (PEO200). After 21 days, pigs were slaughtered and blood and tissue samples were collected. Result showed that PEO200 group significantly increased the average daily gain (ADG) compared with CON group (p < .05). Moreover, PEO supplementation significantly improved the digestibility of DM (p < .05). However, it significantly decreased the serum triglyceride and cholesterol concentration (p < .05). Interestingly, PEO supplementation significantly increased the activity of sucrase in the duodenal and the activity of lactase in the jejunal mucosa (p < .05). Moreover, PEO supplementation improved the growth of intestinal mucosa. As compared to the CON group, the jejunum and ileum villus height were significantly elevated in the PEO200 group (p < .05). Importantly, the expression levels of critical genes associated with nutrient transportation (i.e., GLUT2 and SGLT1) and barrier function (occludin) were significantly elevated in the PEO200 group (p < .05). Moreover, the PEO100 and PEO200 group had higher propionic acid concentration and higher total bacterial gene copies in colon digesta than the CON group (p < .05) respectively. These results not only suggest that PEO has a positive role in the regulation of growth and intestinal health in weaned pigs, but also offer a potential candidate substituting the conventionally used antibiotics in the livestock industry.     

Pathogenesis of porcine enteric calicivirus-like virus in four-day-old gnotobiotic pigs

Eighteen 4-day-old gnotobiotic pigs were orally inoculated with porcine enteric calicivirus-like virus (C strain). Seven additional gnotobiotic pigs served as noninoculated controls. Mild diarrhea developed in all inoculated pigs by postinoculation day (PID) 3 and persisted for 3 to 7 days. Severe diarrhea developed in 2 inoculated pigs between PID 4 and 5. Twelve inoculated and 7 control pigs were euthanatized over a 7-day period. Small intestinal mucosal smears were stained with a fluorescein-conjugated anti-porcine enteric calicivirus-like virus serum. Immunofluorescence was observed in villous epithelial cells (primarily in the duodenum or jejunum) of all inoculated pigs, except for 1 pig euthanatized at PID 7. Villus length was determined in histologic sections of the small intestinal specimens from control and inoculated pigs. Statistically significant (P less than 0.01) villus atrophy was found in the duodenum and/or jejunum of inoculated pigs at PID 3 to 7. These observations were confirmed by scanning electron microscopy, which revealed shortening, blunting, fusion, or absence of villi in the duodenum and jejunum of inoculated pigs at PID 3 to 7. Lesions were not seen in control pigs. Calicivirus-like particles were detected by immune electron microscopy in the large intestinal contents and feces of inoculated pigs from PID 1 to 7.     

Lactulose as a marker of intestinal barrier function in pigs after weaning

Intestinal barrier function in pigs after weaning is almost exclusively determined in terminal experiments with Ussing chambers. Alternatively, the recovery in urine of orally administered lactulose can be used to assess intestinal permeability in living animals. This experiment was designed to study the barrier function of the small intestine of pigs over time after weaning. The aim was to relate paracellular barrier function (measured by lactulose recovery in the urine) with macromolecular transport [measured by horseradish peroxidase (HRP) using Ussing chambers] and bacterial translocation to assess whether lactulose recovery is related to possible causes of infection and disease. Forty gonadectomized male pigs (6.7 ± 0.6 kg) were weaned (d 0) at a mean age of 19 d, fitted with urine collection bags, and individually housed. Pigs were dosed by oral gavage with a marker solution containing lactulose (disaccharide) and the monosaccharides l-rhamnose, 3-O-methylglucose, and d-xylose at 2 h and at 4, 8, and 12 d after weaning. The recovery of sugars in the urine was determined over 18 h after each oral gavage. The day after each permeability test, the intestines of 10 pigs were dissected to determine bacterial translocation to the mesenteric lymph nodes and jejunal permeability for HRP in Ussing chambers. Recovery of l-rhamnose in urine was affected by feed intake and by the time after weaning (P ≤ 0.05). Recovery of lactulose from the urine was greater (P ≤ 0.05) at 4, 8, and 12 d after weaning compared with the first day after weaning and was negatively correlated with feed intake (r = -0.63, P ≤ 0.001). The mean translocation of aerobic bacteria to the mesenteric lymph nodes was greater at 5 and 13 d after weaning compared with d 1 (P ≤ 0.05). Lactulose recovery showed no correlation with permeability for HRP nor with bacterial translocation (P > 0.05). Although both lactulose recovery and bacterial translocation increased over time after weaning, lactulose recovery did not correlate with the permeability for HRP nor bacterial translocation within a pig (P > 0.05). Therefore, we conclude that lactulose recovery in the urine of pigs after weaning is not associated with risk factors for infections. However, it appears to be possible to measure paracellular barrier function with orally administered lactulose in pigs shortly after weaning. Further studies will reveal whether this variable is relevant for the long-term performance or health of pigs after weaning.     

罗格列酮对断奶仔猪肠黏膜结构和抗氧化能力的影响

试验研究罗格列酮(ROS)对脂多糖(LPS)刺激的断奶仔猪肠黏膜结构和抗氧化能力的影响。试验包括3个处理组,对照组注射生理盐水,LPS组注射100μg/kg体重的LPS,ROS组在注射LPS之前的30min注射3mg/kg体重的ROS。注射LPS3h后取样。结果表明:ROS提高了十二指肠和回肠DNA的含量(P0.05);ROS缓解了LPS导致的十二指肠、空肠和回肠隐窝深度的增加(P0.10)和绒毛高度/隐窝深度的降低(P0.01);ROS降低了空肠丙二醛含量(P0.10),提高了十二指肠和空肠SOD活性(P0.05)。结果表明,ROS可能是通过提高肠道抗氧化功能而对LPS刺激的断奶仔猪小肠形态结构的损伤起到一定保护作用。     

不同纤维源日粮对猪肠道菌群影响的研究进展

猪只日粮中添加纤维会在一定程度上降低营养物质的吸收效率,但是饲粮纤维可在猪只肠道后端进行一定程度的发酵,并产生大量的挥发性脂肪酸,具备了一定的营养作用.同时,也因此而降低猪只肠道pH,影响肠道菌群丰度及菌群结构.通过改变纤维日粮的组成来影响肠道中的菌群,发挥肠道上皮屏障功能,并且通过调节肠道微生物的组成来维持肠道微生物...     

Effect of glutamine and spray-dried plasma on growth performance, small intestinal morphology, and immune responses of Escherichia coli K88+-challenged weaned pigs

Forty weaned barrows (5.32 +/- 0.3 kg BW) at 17 +/- 2 d of age were used to investigate the effects of feeding glutamine and spray-dried plasma on the growth performance, small intestinal morphology, and immune responses of Escherichia coli K88-challenged pigs. Pigs were allotted to four treatments including: 1) nonchallenged control (NONC); 2) challenged control (CHAC); 3) 7% (as-fed basis) spray-dried plasma (SDP); and 4) 2% (as-fed basis) glutamine (GLN). On d 11 after weaning, all pigs were fitted with an indwelling jugular catheter. On d 12 after weaning, pigs in the CHAC, SDP, and GLN groups were orally challenged with skim milk E. coli K88 culture, whereas pigs in the NONC group were orally inoculated with sterilized skim milk. Rectal temperatures and fecal diarrheic scores were recorded and blood samples collected at 0 (baseline), 6, 12, 24, 36, and 48 h after the challenge for serum hormone and cytokine measurements. At 48 h postchallenge, all pigs were killed for evaluation of small intestinal morphology. There was no effect of feeding SDP or GLN on growth performance during the 11-d prechallenge period (P = 0.13). At 48 h after the challenge, CHAC pigs had decreased ADG (P = 0.08) and G:F (P = 0.07) compared with the NONC pigs; however, SDP and NONC pigs did not differ in G:F, and GLN and NONC pigs did not differ for ADG and G:F. At 6, 36, and 48 h after the challenge, CHAC, SDP, and GLN pigs had increased rectal temperature relative to the baseline (P = 0.09). At 12 and 36 h after the challenge, CHAC pigs had the highest incidence of diarrhea among treatments (P = 0.08). Serum IL-6 and ACTH were not affected by treatment or time after E. coli challenge (P = 0.11). In proximal, midjejunum, and ileum, CHAC pigs had greater villous atrophy and intestinal morphology disruption than NONC pigs (P < 0.01), whereas SDP and GLN pigs had mitigated villous atrophy and intestinal morphology impairment after E. coli challenge. Pigs in the SDP had the lowest GH at 12 h and the greatest GH at 36 h after the challenge among treatments (P = 0.08). Pigs in the NONC had the highest IGF-1 at 12 and 36 h postchallenge (P < 0.04). These results indicate that feeding glutamine has beneficial effects in alleviating growth depression of E. coli K88-challenged pigs, mainly via maintaining intestinal morphology and function, and/or possibly via modulating the somatotrophic axis.     

仔猪补饲及不同类型的饲粮蛋白质对仔猪小肠粘膜形态结构的影响

试验研究了玉米—豆饼(CSM)、豆饼(SM)、乙醇处理豆饼(TSM)和乳蛋白(MP)等不同类型蛋白质对3周龄断奶仔猪小肠形态变化的影响。仔猪从7日龄起补饲,断奶后一部分仔猪换喂复合开食料(CS),其余仔猪饲料类型不变。试验至35日龄结束。结果表明,断奶导致绒毛变短(P<0.05),腺窝增深(P<0.05),绒毛/腺窝比下降(P<0.01),空肠上皮淋巴数增加(P<0.05),蔗糖酶活降低(P<0.01),血清脲氮上升(P<0.01)。断奶后肠道损伤程度与蛋白类型有关(P<0.01):豆饼引起的损伤程度最大,乳蛋白最小;玉米代替部分豆饼或用乙醇处理豆饼后可明显降低小肠粘膜损伤程度。断奶后换料组的粘膜损伤比相同料型组严重(P<0.01),但补饲豆饼组例外。十二指肠的绒毛萎缩(P>0.05)和腺窝增深(P<0.01)比空肠明显。断奶后第一周肠粘膜损伤最严重,第二周开始恢复。这些结果充分证明,仔猪对补饲及不同类型蛋白质的反应符合过敏理论。     

Effect of susceptibility to enterotoxigenic Escherichia coli F4 and of dietary tryptophan on gut microbiota diversity observed in healthy young pigs

Healthy weaned pigs susceptible to enterotoxigenic Escherichia coli F4 (ETEC) require more tryptophan (Trp) to maximize their performance. This may be related to an effect on intestinal microbiota. We studied the intestinal bacterial diversity of healthy pigs with different susceptibility to ETEC and fed different Trp levels. Thirty-six littermate weaned pigs were selected to obtain a set potentially formed of 50% ETEC-susceptible and 50% non-susceptible pigs, based on a Mucin 4 gene polymorphism. Pigs were fed a diet with 0.17 (TrpL) or 0.22 (TrpH) standardized ileal digestible Trp:Lys ratio for 21 days. Slaughtered pigs were classified into non-susceptible, mildly susceptible, and susceptible, by testing ETEC adhesion to intestinal villi. Bacterial diversity in jejunum content was assessed by the 16S rRNA gene-targeted denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis and expressed by the Shannon index. Susceptible pigs had a reduced bacterial diversity, particularly with TrpL diet (p = 0.003). The ETEC adhesion class affected the quantification of enterobacteria DNA (p = 0.027). One DGGE band, which referred to Clostridium bartlettii, was not evidenced in all the susceptible pigs; less DNA from this microbe was quantified by RT-PCR in the jejunum from TrpH susceptible pigs (p = 0.025) compared to TrpL. The gene expression for β-galactoside α-2,3-sialyltransferase 1 was higher in jejunal tissue of ETEC-susceptible pigs (p = 0.019). In studies on pig gut microbiota, the presence of intestinal receptors for ETEC should be considered because of their contribution to a reduced bacterial diversity. This effect could be partially reversed by dietary Trp addition.     

纳米氧化锌对断奶仔猪生长、腹泻、肠道微生物和通透性的影响

选用108头平均体重为7.2 kg杜×长×大断奶仔猪,随机分成3组,对照组饲喂基础饲粮;氧化锌组在基础饲粮中添加2 000 mg/kg锌(氧化锌);纳米氧化锌组在基础饲粮中添加500 mg/kg锌(纳米氧化锌),试验期14 d。结果表明:与对照组相比,添加500 mg/kg纳米氧化锌和2 000 mg/kg氧化锌分别提高日增重16.20%(P<0.05)和14.94%(P<0.05),提高日采食12.63%(P<0.05)和13.66%(P<0.05),显著降低断奶后7 d和14 d腹泻指数(P<0.05),显著降低血浆D-乳酸和二胺氧化酶活性(P<0.05)。添加500 mg/kg纳米氧化锌显著降低小肠和结肠内容物中梭菌和大肠杆菌数量;添加2 000 mg/kg氧化锌显著降低结肠内容物中梭菌数量。结果提示,断奶仔猪饲粮中添加500 mg/kg锌(纳米氧化锌)可提高仔猪生长性能,降低腹泻率和肠道通透性,改善肠道微生态,其效果与添加2 000 mg/kg锌(氧化锌)相当。     

Transport stress induces pig jejunum tissue oxidative damage and results in autophagy/mitophagy activation

Pig transportation is associated with intestinal oxidative stress and results in destruction of intestinal integrity. Autophagy has been contributed to maintain cell homeostasis under stresses. The purpose of this study was to evaluate the effects of transport stress on morphology, intestinal mucosal barrier and autophagy/mitophagy levels in pig jejunum. A total of 16 finishing pigs were randomly divided into two groups. The control group was directly transported to the slaughterhouse and rested for 24 hr. The experimental groups were transported for 5 hr and slaughtered immediately. The results showed that transportation induced obvious stress responses with morphological and histological damage in jejunum accompanying with an elevated level of malondialdehyde (MDA; p < .05), endotoxin (LPS; p < .05), lactic dehydrogenase (LDH; p < .05) and a decreased level of serum superoxide dismutase (SOD; p < .05). Also, hemeoxy genase 1 (HO‐1; p < .01) as well as tight junction protein (claudin‐1 [p < .001], occludin [p < .05] and zonula occludens 1 [ZO‐1; p < 0.05]) levels were attenuated in jejunum tissue, and NADPH oxidase 1 (NOX1; p < .01) mRNA expression was up‐regulated. Further research indicated that transport stress could induce autophagy through increasing microtubule‐associated protein light chain 3 (LC3; p < .05) and autophagy‐related gene 5 (ATG5; p < .01) levels and suppressing p62 expression. Additionally, transport stress increased the protein levels of PTEN‐induced putative kinase 1 (PINK1; p < .05) and Parkin (p < .05) which was associated with mitophagy. In conclusions, transport stress could induce the destruction of intestinal integrity and involve in the intestinal mucosal barrier oxidative damage, and also contribute to activation of autophagy/mitophagy.     

Effects of Escherichia coli heat-stable enterotoxin b on small intestinal villi in pigs, rabbits, and lambs

Culture supernates from two strains of E. coli were placed into different ligated intestinal sections (loops) of each animal. The two bacterial strains were identical except that one contained a plasmid carrying the heat-stable toxin b (STb) gene, while the other did not. Morphometric techniques were used to assess villous epithelial surface areas and mucosal volumes in both intestinal segments exposed to STb-positive (test) and to STb-negative (control) supernates. In pigs whose intestines were exposed to STb-positive supernatants for 2 hours, both villous epithelial surface area and mucosal volume were significantly smaller in test loops than in control loops (P less than 0.02). In test loops of pigs incubated for 1 hour, and in test loops of lambs incubated for 2 hours, there was a decrease in villous epithelial surface area which approached the test for significance but did not meet it (0.05 less than P less than 0.10). Rabbit test loops did not differ from rabbit control loops in either villous epithelial surface area or mucosal volume. Histological examination of the tissues from all three species revealed epithelial changes in porcine and ovine tissues only. In porcine and ovine tissues, epithelium at villous tips was seen to be cuboidal or squamous, or even to be absent. Villi with similarly altered epithelium were seen in control loops, but were seen much more frequently in test loops. These epithelial changes were seen as early as 30 minutes of incubation in pigs. Intestinal tissues from these pigs were examined by transmission electron microscopy, but no difference between test and control tissues was seen.(ABSTRACT TRUNCATED AT 250 WORDS)     

纳米载铜蒙脱石对断奶仔猪生长、肠道菌群及其肠黏膜形态的影响

选用128头健康“杜长大”三元杂交断奶仔猪,随机分为对照组、CuSO4组、纳米蒙脱石(MMT)组和MMT-Cu组,分别饲喂基础日粮(对照组)、基础日粮+78 mg/kg Cu2+(CuSO4.5H2O,相当于MMT-Cu中Cu2+的量)、基础日粮+2.0 g/kgMMT、基础日粮+2.0 g/kgMMT-Cu。结果表明,与对照组相比,MMT-Cu组能显著提高(P<0.05)断奶仔猪的平均日增重、饲料转化效率及小肠绒毛高度、绒毛高度与隐窝深度的比值,显著降低(P<0.05)腹泻率及小肠、结肠内容物中大肠杆菌和沙门氏菌的数量;而MMT组也显著降低(P<0.05)仔猪腹泻率,提高(P<0.05)小肠绒毛高度和绒毛高度与隐窝深度的比值。与MMT组或CuSO4组相比,MMT-Cu组能显著(P<0.05)提高断奶仔猪的平均日增重和饲料转化效率(P<0.05),显著降低了(P<0.05)小肠和结肠内容物中大肠杆菌和沙门氏菌的数量。     

Experimentally induced porcine proliferative enteritis in specific-pathogen-free pigs

Thirty-three, 10-week-old, specific-pathogen-free pigs were randomly allotted to 3 treatment groups: group 1--intragastrically given homogenized intestinal mucosa (crude inoculum) from pigs with naturally occurring proliferative enteritis; group 2--given cultures of Campylobacter sputorum subsp mucosalis; and group 3--controls. One pig from each group was killed 4, 7, 10, 14, 18, 21, 24, 28, 31, 36, and 38 days after inoculation. The earliest intestinal lesion observed in groups 1 and 2 was leukocytic exudate within crypt lumina and focal inflammation of the surrounding lamina propria. The lesions occurred primarily over ileal aggregated lymphoid nodules (Peyer's patches). These changes were followed by focal proliferation of immature crypt epithelial cells and infiltration of increasing numbers of macrophages into the lamina propria. Campylobacter sp-like organisms were observed within the cytoplasm of affected epithelial cells by light and electron microscopies. Lesions progressed to diffuse crypt cell proliferation, elongation of crypts, and loss of villi. Mucosal necrosis was not a prominent feature.     

Dietary copper/zinc-loaded montmorillonite improved growth performance and intestinal barrier and changed gut microbiota in weaned piglets

The effects of copper/zinc-loaded montmorillonite (Cu/Zn-Mt) on growth performance, intestinal barrier and gut microbiota of weaned pigs were investigated in the present study. A total of 108 piglets (Duroc × Landrace × Yorkshire; 6.36 kg; weaned at 21 ± 1 d age) were used in this experiment. The pigs were randomly assigned to three treatments with six replicates, six pigs in each replicate. The three treatments were as follows: (1) control group: basal diet; (2) Cu/Zn-Mt group: basal diet supplemented with 39 mg/kg Cu and 75 mg/kg Zn as Cu/Zn-Mt; and (3) Cu +Zn +Mt group: basal diet supplemented with the mixture of copper sulphate, zinc sulphate and montmorillonite (equivalent to the copper and zinc in the Cu/Zn-Mt treatment). The results indicated that, compared with the pigs from control group, average daily gain and gain: feed ratio were increased and the faecal score on days 7 and 14 after weaning was decreased by supplementation of Cu/Zn-Mt; intestinal transepithelial electrical resistance (TER) and expressions of tight junction protein claudin-1 and zonula occludens-1 were increased, and intestinal permeability of fluorescein isothiocyanate-dextran 4 kDa was decreased by supplementation with Cu/Zn-Mt. According to the Illumina-based sequencing results, Cu/Zn-Mt supplementation increased the relative abundance of core bacteria (Lactococcus, Bacillus) at genus level and decreased the potentially pathogenic bacteria (Streptococcus and Pseudomonas) in colon of weaned piglets. However, the piglets fed with the mixture of copper sulphate, zinc sulphate and montmorillonite showed no effects in above parameters in comparison with the pigs from control group. In conclusion, dietary Cu/Zn-Mt could improve growth performance, decrease the diarrhoea and improve intestinal barrier and bacterial communities of weaned pigs. The results indicated that ‘loading’ of montmorillonite with Zn and Cu changed not only its chemical but also its nutritional properties.