28 Influence of corn based fibrous co-products on ileal mucosa gene expression and mucosal associated microbiome of growing pigs

Abstract

The microbiome located on the mucosal layer of the gastrointestinal tract is essential for nutrient exchange and host communication. Understanding the presence of the microbiome and its relationship to the host gene expression is essential to fully understand nutrient uptake and ingredient utilization. High inclusions of industrial corn co-products in grow-finish diets may affect gastrointestinal tissue function and alter microbial community structure. The objective of this study was to determine the influence of insoluble corn-based fibers (ICBF) on small intestine microbial communities and ileal transcriptome of growing pigs. Two replicates of 28 gilts (26.7 ± 2.5 kg BW; PIC800 x Camborough; N=56), were randomly assigned to one of 7 semi-synthetic diets. Dietary treatments included a control (CTL) diet with a formulated total dietary fiber (TDF) value of < 1% and 6 diets with an ICBF replacing 30% of the corn starch in CTL: dehulled degermed corn (DHDG; TDF = 0.89%), ground corn (COR; TDF = 3.80%), corn gluten meal (CGM; TDF = 4.36%), high protein dried distillers grains (HP; TDF = 7.00%), dried distillers grains (DDGS; TDF = 7.93%), and corn bran (BRN; TDF = 12.29%). Pigs were individually housed and limit-fed 2.4 times maintenance. On day 31 pigs were necropsied. Mucosal scrapings and tissue were collected from the ileum for 16S rRNA gene microbiota analysis and host differential expressed genes (DEG), respectively. Individual operational taxonomic units (OTU) were compared using Linear Discriminant Analysis Effect Size. Data for alpha diversity metrics were analyzed as a mixed model with replicate as random effect and treatment as fixed effect. Sixty of the top 100 OTUs differed across dietary treatments, mainly from the families Clostridiaceae, Enterobacteriaceae, and Streptococcaceae. There were no differences among observed species richness, Chao1, or Shannon alpha diversity indices. Simpson evenness tended to increase with increasing level of ICBF (P=0.09). Diets containing ICBF were compared to CTL for DEG. Protein-coding genes were selected based on a false discovery rate ≤0.05 and log2 fold change >|2|. Of the 23 genes that met these criteria, 14 were associated with intestinal integrity and cellular homeostasis. Differences were primarily identified in the high fiber diets: HP, DDGS, and BRN. Genes associated with stress response, CHAC1 and ATF5, were down regulated in HP compared to CTL (Q< 0.05). RND3 (RhoE) and WHRN are associated with regulating actin in the cytoskeleton and maintaining structure and function of the intestinal epithelium and were up regulated in DDGS relative to CTL (Q< 0.05). SERPINB5, TPPP3, and RFX2 were up regulated in BRN relative to CTL(Q< 0.05). These genes are associated with cellular structure and proliferation. In summation, these data imply corn co-products influence the small intestine microbiota and alter host gene expression in growing pigs.