Long-term effects of early antibiotic intervention on blood parameters,apparent nutrient digestibility, and fecal microbial fermentation profile in pigs with different dietary protein levels

Backgroud： This study aimed to determine the effects of early antibiotic intervention（EAI） on subsequent blood parameters, apparent nutrient digestibility, and fecal fermentation profile in pigs with different dietary crude protein（CP） levels. Eighteen litters of piglets（total 212） were randomly allocated to 2 groups and were fed a creep feed diet with or without in-feed antibiotics（olaquindox, oxytetracycline calcium and kitasamycin） from postnatal d 7 to d 42. On d 42, the piglets within the control or antibiotic group were mixed, respectively, and then further randomly assigned to a normal-（20%, 18%, and 14% CP from d 42 to d 77, d 77 to d 120, and d 120 to d 185,respectively） or a low-CP diet（16%, 14%, and 10% CP from d 42 to d 77, d 77 to d 120, and d 120 to d 185,respectively）, generating 4 groups. On d 77（short-term） and d 185（long-term）, serum and fecal samples were obtained for blood parameters, microbial composition and microbial metabolism analysis.Results： EAI increased（P 〈 0.05） albumin and glucose concentrations in low-CP diet on d 77, and increased（P 〈 0.05） urea concentration in normal-CP diet. On d 185, EAI increased（P 〈 0.05） globulin concentration in normal-CP diets, but decreased glucose concentration. For nutrient digestibility, EAI increased（P 〈 0.05）digestibility of CP on d 77. For fecal microbiota, the EAI as well as low-CP diet decreased（P 〈 0.05） E. coli count on d 77. For fecal metabolites, on d 77, EAI decreased（P 〈 0.05） total amines concentration but increased skatole concentration in low-CP diet. On d 185, the EAI increased（P 〈 0.05） putrescine and total amines concentrations in low-CP diets but reduced（P 〈 0.05） in the normal-CP diets. The low-CP diet decreased the concentrations of these compounds.Conclusions： Collectively, these results indicate that EAI has short-term effects on the blood parameters and fecal microbial fermentation profile. The effects of EAI varied between CP levels, which was characterized by the significant alteration of glucose and putrescine concentration.

猪不同肠段微生物体外培养对蛋氨酸的代谢特性

【目的】旨在通过微生物体外发酵技术,以回肠微生物为参照,研究猪盲肠及结肠微生物对在小肠微生物中代谢率较低的蛋氨酸的代谢特性。【方法】采集4头健康100 kg左右杜×长×大杂交猪的盲肠、结肠与回肠食糜作为接种物,分别接种于10 mmol/L蛋氨酸的培养基中,37°C体外培养24 h。分别设含蛋基酸溶液和含各肠段食糜接种物的空白对照组。【结果】(1)不同肠段微生物以蛋氨酸为底物体外发酵,盲肠组蛋氨酸消失率(21.9%)显著高于结肠组(16.7%)与回肠组(16.3%)(P<0.05)。盲肠组总SCFA量显著高于结肠与回肠组(P<0.05),伴随着p H值下降程度最高;盲肠组MCP产量也显著高于结肠与回肠组(P<0.05);在产气量与NH3-N浓度上,盲肠组与结肠组均显著低于回肠组(P<0.05)。(2)以蛋氨酸为底物体外发酵,门水平上,总菌、厚壁菌门含量在各肠段组间无显著差异(P>0.05),拟杆菌门含量在盲肠组最高;与不加蛋氨酸底物的对照组比较,三个肠段试验组总菌、厚壁菌门含量均显著高于对照组(P<0.05),而拟杆菌门含量在试验组与对照组间差异不显著(P>0.05)。属水平上,盲肠组和结肠组大肠杆菌属数量显著低于回肠组(P<0.05),而柔嫩梭菌属和梭菌XIV属数量在盲肠组和结肠组均高于回肠组;各肠段组间双歧杆菌数量无显著差异(P>0.05)。【结论】以蛋氨酸为底物,体外培养猪盲肠微生物对蛋氨酸代谢率高于回肠微生物,伴随着其他发酵参数的变化,并且发酵产生更多的菌体蛋白。相比于回肠微生物发酵,大肠微生物发酵后,柔嫩梭菌属和梭菌XIV属数量较高,而大肠杆菌属数量较低。

猪源乳杆菌Lactobacillus reuteri strain DSM和Lactobacillus taiwanensis strain BCRC对肠道炎症的影响

【目的】旨在以葡聚糖硫酸钠(DSS)诱导小鼠肠炎模型研究猪源乳杆菌Lactobacillus reuteri strain DSM(LR)和Lactobacillus taiwanensis strain BCRC(LT)对肠道炎症的影响。【方法】选取24只8周龄体重相近的C57BL/6J雄性小鼠,随机分为4组(每组6个重复):正常对照组、DSS组、LR菌处理组(DSS+LR)和LT菌处理组(DSS+LT)。适应期7 d,试验期16 d,随后处死小鼠并采样。【结果】与正常对照组相比,DSS组小鼠体重、结肠长度显著降低,疾病活动指数(DAI)显著增加(P<0.05);与DSS组相比,LR、LT菌处理组小鼠体重下降的程度并没有显著缓解,但是,其DAI评分显著降低;并且,LT菌处理组结肠长度显著增加(P<0.05)。正常对照组和LT菌处理组结肠组织病理学评分显著低于DSS组和LR菌处理组(P<0.05)。结肠髓过氧化物酶(MPO)活性在正常对照组和LT菌处理组也显著低于DSS组(P<0.05),在LR菌处理组与DSS组无显著差异(P>0.05)。与正常对照组相比,DSS组结肠和血浆的促炎因子TNF-α、IL-1β、IL-6水平显著升高,而抗炎因子IL-10水平显著降低;相比于DSS组,LT菌处理组显著降低了结肠和血浆的TNF-α、IL-1β、IL-6水平,升高了IL-10水平;LR菌处理组显著降低了结肠TNF-α水平、血浆IL-1β水平,升高IL-10水平(P<0.05)。免疫组化和ELISA结果显示,相比于正常对照组,DSS组降低了结肠紧密连接蛋白Claudin-1、Occludin、ZO-1和黏蛋白Muc-2表达水平,而LR或LT菌的处理则上调了DSS影响下的屏障相关蛋白表达。16S rDNA测序技术检测结肠菌群组成,PCoA分析得出,正常对照组和DSS组显著分离,LT处理组菌群组成更接近于正常对照组。门水平上,变形菌门丰度在正常对照组显著低于DSS组(P<0.05);与DSS组相比,LT菌处理组也能降低变形菌门丰度,但未达显著水平(P>0.05)。属水平上,Muribaculaceae_norank属在正常对照组显著高于其他3组,Bacteroides在正常对照组显著低于其他3组(P<0.05);与DSS组相比,LR或LT菌的处理增加了Muribaculaceae_norank丰度,降低了Bacteroides菌丰度,但差异不显著(P>0.05)。【结论】乳杆菌Lactobacillus reuteri和Lactobacillus taiwanensis能增强肠上皮屏障,对DSS引起的肠道炎症起到了一定的缓解作用;其中,Lactobacillus taiwanensis对肠上皮屏障的保护效果更为明显。

Amino acid sensing in the gut and its mediation in gut-brain signal transduction

Animal gastrointestinal tract is not only a digestive organ, but also a nutrient sensing organ which detects luminal nutrient and thus can regulate food intake. There are many amino acid sensing receptors and transporters in the gut. Amino acids sensing by these receptors and transporters can stimulate the intestinal endocrine cells to release a variety of gut hormones. These hormones trigger a series of physiological effects via the nerve system. This review summarized the recent advance on the amino acid sensing receptors and transporters in the gastrointestinal tract, the gut hormones released from the intestinal endocrine cells and the hormones-induced signal transduction between the gut and brain. A better understanding of these processes may help to gain further insight into the specific role of amino acids in digestion and provide guidelines in developing strategy for the better use of amino acids in the diet.

Comparisons of blood biochemical parameters,digestive enzyme activities and volatile fatty acid profile between Meishan and Yorkshire piglets

This study was conducted to compare physiological characteristics between Meishan and Yorkshire piglets in their early lives. Six healthy purebred Meishan sows and Yorkshire sows with close farrowing dates were used in this research. The piglets sucked their respective sow’s milk for 14 days, then they were slaughtered to collect samples of blood, pancreas, contents of stomach, jejunum, cecum, colon as well as feces for analysis of blood biochemical parameters, digestive enzymes, and volatile fatty acid(VFA). The results showed that Yorkshire piglets had higher concentrations of high-density lipoprotein cholesterol(HDL-C) and total cholesterol(TC)(P < 0.05). Gastric lipase activity was higher in Meishan piglets but Yorkshire piglets had higher lactase activity(P < 0.05). The total VFA together with acetate and propionate in cecum and colon were higher in Meishan piglets than in Yorkshire piglets(P < 0.05),but acetate in jejunum and ratio of acetate to propionate in colon were lower in Meishan piglets than in Yorkshire piglets(P < 0.05). In conclusion, in early suckling period, significant differences exist in host metabolism and intestinal microbial metabolism between Meishan and Yorkshire piglets.

Propionate stimulates the secretion of satiety hormones and reduces acute appetite in a cecal fistula pig model

Short-chain fatty acids(SCFA)can regulate appetite by stimulating the secretion of satiety hormones.However,the impact of short-chain fatty acid propionate on the release of gut satiety hormones and appetite regulation in pigs is not completely understood.In this study,16 pigs were infused with saline or sodium propionate through a fistula in the caecum during a 28-day experimental period.We characterized the effects of propionate administration on peptide YY(PYY)and glucagon-like peptide 1(GLP-1)secretion from colonic tissue,and investigated the role of propionate infusion on the expression of appetite-related genes in the colon and hypothalamus.Further,the direct impact of propionate administration on the expression of orexigenic neuropeptide agouti-related protein(AgRP)in hypothalamic N38 cells was also examined.The results showed that intra-cecal infusion of propionate reduced the short-term feed intake(P<0.05)but not the long-term feed intake in pigs(P>0.05).Propionate administration stimulated PYY and GLP-1 release from colon tissue in vivo and ex vivo(P<0.05).It also upregulated PYY expression in the colonic mucosa(P<0.05).Meanwhile,the GLP-1 and PYY levels in the blood were increased after intra-cecal infusion of propionate at d 28(P<0.05).Additionally,intra-cecal infusion of propionate upregulated the mRNA and protein expression of free fatty acid receptor 2/3(FFAR2/FFAR3)in the colonic mucosa(P<0.05).Propionate infusion also downregulated the orexigenic AgRP mRNA expression(P<0.05)and upregulated the anorexigenic cocaine-and amphetamine-regulated transcript(CART)mRNA expression(P=0.09)in the hypothalamus.Moreover,propionate administration directly downregulated AgRP expression in hypothalamic N38 cells in a dose-dependent manner(P<0.05).Collectively,these findings demonstrated that cecal propionate stimulated colonic secretion of satiety hormones and suppressed appetite to reduce the short-term feed intake in pigs.This study highlights that microbial-derived propionate exerts an important role in regulating the physical functions of the host.