Institute of Animal Nutrition and Functional Plant Compounds, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinaerplatz, Vienna, Austria.
Teagasc Pig Development Department, Animal & Grassland Research & Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland.
J Anim Sci. 2018 Jun 4;96(6):2249-2264. doi: 10.1093/jas/sky118.
Little is known about the role of the gut mucosal microbiota and microbe-host signaling in the variation of pig's feed efficiency (FE). This study therefore aimed to investigate the FE-related differences in the metabolically active mucosal bacterial microbiota and expression of genes for innate immune response, barrier function, nutrient uptake, and incretins in the cecum of finishing pigs. Pigs (n = 72) were ranked for their residual feed intake (RFI; metric for FE) between days 42 and 91 postweaning and were stratified within litter and sex into high (HRFI; n = 8) and low RFI (LRFI; n = 8). Cecal mucosa and digesta were collected on day 137-141 of life. After isolating total RNA from the mucosa, the RNA was transcribed into cDNA which was used for gene expression analysis, total bacterial quantification, and high-throughput sequencing (Illumina MiSeq) of the hypervariable V3-V4 region of the 16S rRNA gene. The RFI differed by 2.1 kg between low RFI (LRFI; good FE) and high RFI (HRFI; poor FE) pigs (P < 0.001). The cecal mucosa was mainly colonized by Helicobacteraceae, Campylobacteraceae, Veillonellaceae, Lachnospiraceae, and Prevotellaceae. Despite the lack of differences in microbial diversity and absolute abundance, RFI-associated compositional differences were found. The predominant genus Campylobacter tended (P < 0.10) to be 0.4-fold more abundant in LRFI pigs, whereas low abundant Escherichia/Shigella (P < 0.05), Ruminobacter (P < 0.05), and Veillonella (P < 0.10) were 3.4-, 6.6-, and 4.4-fold less abundant at the cecal mucosa of LRFI compared to HRFI pigs. Moreover, mucin 2 and zona occludens-1 were less expressed (P < 0.05) in the cecal mucosa of LRFI compared to HRFI pigs. Cecal mucosal expression of monocarboxylate transporter-1, glucagon-like peptide-1, and peptide YY further tended (P < 0.10) to be downregulated in LRFI compared to HRFI pigs, indicating an enhanced VFA uptake and signaling in HRFI pigs. Sparse partial least square regression and relevance networking support the hypothesis that certain mucosal bacteria and luminal microbial metabolites were more associated than others with differences in RFI and cecal gene expression. However, present results do not allow the determination of whether mucosal bacterial changes contributed to variation in FE or were rather a consequence of FE-related changes in the pig's physiology or feeding behavior.
关于肠道黏膜微生物群和微生物-宿主信号在猪饲料效率（FE）变化中的作用，人们知之甚少。因此，本研究旨在研究育肥猪回肠黏膜中与代谢活跃的黏膜细菌微生物群和先天免疫反应、屏障功能、营养吸收和肠降血糖素相关的基因表达的 FE 相关差异。在断奶后 42 至 91 天期间，根据剩余饲料摄入量（FE 的衡量标准）对猪进行排名，并按窝和性别在高（HRFI；n=8）和低 RFI（LRFI；n=8）之间进行分层。在生命的第 137-141 天收集回肠黏膜和内容物。从黏膜中分离出总 RNA 后，将 RNA 转录为 cDNA，用于基因表达分析、总细菌定量和 16S rRNA 基因高变区 V3-V4 区的高通量测序（Illumina MiSeq）。低 RFI（LRFI；良好的 FE）和高 RFI（HRFI；较差的 FE）猪之间的 RFI 差异为 2.1kg（P<0.001）。回肠黏膜主要定植有螺旋杆菌科、弯曲杆菌科、韦荣球菌科、lachnospiraceae 和 prevotellaceae。尽管微生物多样性和绝对丰度没有差异，但发现了与 RFI 相关的组成差异。优势属弯曲杆菌（Campylobacter）在 LRFI 猪中丰度（P<0.10）高出 0.4 倍，而低丰度的大肠杆菌/志贺氏菌（Escherichia/Shigella）（P<0.05）、真杆菌（Ruminobacter）（P<0.05）和韦荣球菌（Veillonella）（P<0.10）在 LRFI 猪中的丰度分别低 3.4、6.6 和 4.4 倍。此外，LRFI 猪回肠黏膜中粘蛋白 2 和闭合蛋白-1 的表达（P<0.05）较低。LRFI 猪回肠黏膜中单羧酸转运蛋白-1、胰高血糖素样肽-1 和肽 YY 的表达进一步趋于（P<0.10）下调，表明 HRFI 猪中 VFA 的摄取和信号转导增强。稀疏偏最小二乘回归和相关性网络支持这样的假设，即某些黏膜细菌和腔微生物代谢物与 RFI 和回肠基因表达的差异比其他细菌和代谢物更相关。然而，目前的结果还不能确定黏膜细菌的变化是否有助于 FE 的变化，或者是否是 FE 相关的猪生理或喂养行为变化的结果。
