鉴别二花脸猪耐粗饲的大肠微生物、代谢产物及其宿主肠道功能基因

Erhualian pig, one of Chinese old native pig breeds, is tolerant to forage. Our previous reports showed that compared with the performance of animals from the control group fed with basal diet, ADFI and ADG of Erhualian pigs from the treatment group fed with diet of 7% bran replace of basal diet (NDF 15.11%, IDF 16.32%) were not affected. Whereas, ADFI and ADG of Large white pigs similar in physiological stages to Erhualian pigs decreased significantly. And Erhualian pigs had a significant superiority on the apparent digestibility of fiber (NDF/ CF/ IDF) and relative large intestine length than Large white pigs. This was speculated to be related to the specific development of the intestinal tract, functional microflora abundance, especially the specific specific microbes, metabolites and functional receptor gene of the large intestine of pigs. However, the underlying mechanism remains unclear. In this experiment, large white pigs as the control, large intestinal structural characteristics of some critical development periods of Erhualian pig were analyzed and intestinal development related genes were tapped by using RNA-seq Technology.At the same time, Erhualian pig intestine microbial abundance, metabolites and functional characteristics of receptor genes were analyzed by using metagenomic and metabonomics. Animals were fed with the basal diet or the diet with 7% wheat bran substituted of based diets.The gut microbiology structure of Meishan pigs which were provided the same diet will be detected by 16s rRNA gene sequence to identify common microorganisms of Chinese native breeds . The interaction between the unique gene expression amount, host microbial abundance and their metabolic products abundance and their functional specificity will also been analyzed through bioinformatics analysis. Thus we can systematically analyze the molecular mechanism of combined action of the host and the intestinal microflora of Erhualian pig on its tolerant to forage.

二花脸猪是我国优秀的耐粗饲地方猪种之一，前期研究发现，用7%麸皮替代基础日粮（NDF 15.11%、IDF 16.32%）时，二花脸猪采食量、日增重不受影响，但同生理阶段大白猪显著下降，且二花脸猪纤维表观消化率（NDF/CF/IDF）和大肠相对长度均比大白猪有显著优势，推测与其大肠特有肠道发育、功能微生物丰度、尤其是特异性微生物和代谢产物及其功能受体基因有关，但机制不清。本研究以大白猪为对照，屠宰分析大肠发育关键时期二花脸猪大肠组织结构特性，利用RNA-seq技术挖掘二花脸猪大肠发育基因特征；同时采用宏基因组学和代谢组学技术挖掘从基础日粮到7%麸皮替代基础日粮时，二花脸猪大肠功能微生物丰度、代谢产物及其功能受体基因特征；利用16s rRNA测序探究相同日粮水平饲喂下梅山猪的肠道微生物结构，鉴别地方猪耐粗饲共性微生物；并利用生物信息学分析其宿主肠道基因表达差异与功能微生物及其代谢产物特异性的互作关系，从而系统分析宿主与肠道微生物共同作用影响二花脸猪耐粗饲的分子机制。

二花脸猪是我国优秀的耐粗饲地方猪种之一，前期研究发现，用7%麸皮替代基础日粮时，二花脸猪采食量、日增重不受影响，但同生理阶段大白猪显著下降，且二花脸猪纤维表观消化率（NDF/CF/IDF）和大肠相对长度均比大白猪有显著优势。为初步探究二花脸猪的耐粗饲机制，本研究以大白猪为对照，采用宏基因组学和代谢组学技术挖掘从基础日粮到7%麸皮替代基础日粮时，二花脸猪大肠功能微生物丰度、代谢产物及其功能受体基因特征；利用宏基因组测序探究相同日粮水平饲喂下梅山猪的肠道微生物结构，鉴别地方猪耐粗饲共性微生物；屠宰分析大肠发育关键时期二花脸猪大肠组织结构特性，利用RNA-seq技术挖掘二花脸猪大肠发育基因特征；同时利用生物信息学分析其宿主肠道基因表达差异与功能微生物及其代谢产物特异性的互作关系，分析宿主与肠道微生物共同作用影响二花脸猪耐粗饲的分子机制。研究发现：（1）二花脸猪的肠道微生物具有更高的碳水化合物的运输与代谢、糖代谢、甘露聚糖、半乳糖代谢功能和更多的纤维消化相关酶编码基因，并筛选出5个结肠和15个盲肠中与二花脸猪高纤维消化率性状相关的微生物。（2）二花脸猪和梅山猪鉴定到2个共有的耐粗饲相关候选微生物，分别为Eubacterium_siraeum_CAG:80、Lactobacillus_ruminis。（3）利用代谢组筛选出8个影响二花脸猪高纤维消化的关键代谢物。（4）二花脸猪结肠具有更高的SCFA转运基因（FFAR3）、营养消化吸收相关基因（GLP-2、GLP-2R）表达量，是其具有较高纤维消化率的原因之一。（5）二花脸猪在90和150日龄大肠发育较大白猪更好，且SLC51A、FGF10、GATM、NEDD4、OLR1、CLCA1、GPR85、SLC14A2基因是促进二花脸猪大肠发育的关键候选基因。（6）二花脸猪高纤维消化率表型是由肠道微生物、代谢物及基因互作影响的。与大白猪相比，随着日粮纤维水平的增加，二花脸猪丁酸代谢通路相关酶及代谢物显著富集，这可能是二花脸猪耐粗饲的原因之一。本项目研究可为我国地方猪优良耐粗饲特性的机制解析提供参考，同时可为合理利用我国非常规饲料资源提供理论基础。