Multidisciplinary approach to evaluating the impact of corn-based coproducts and fiber deprivation on swine gastrointestinal function and microbiome
No Thumbnail Available
Authors
Meeting name
Sponsors
Date
Journal Title
Format
Thesis
Subject
Abstract
[EMBARGOED UNTIL 12/01/2026] Corn-derived coproducts are increasingly included into swine diets to help mitigate rising diet formulation costs. These coproducts have increased levels of insoluble dietary fiber (IDF) relative to whole corn, and depending on the milling and extraction process, have varying non-starch polysaccharide composition. Historically, fiber has been considered an antinutrient due to the negative effects associated with digestibility. However, recent work has emphasized its beneficial roles in modulating the gastrointestinal microbiome and promoting host health. This dissertation investigates the effects of insoluble corn-based fiber (ICBF) sources on gut microbiota composition, microbial functional capacity, gastrointestinal morphology, host transcriptomic responses, and nutrient digestibility in growing pigs. Seven experimental diets were formulated, including a fiber-deprived control and six diets with varying sources of ICBF (dehulled degermed corn, ground corn, corn gluten meal, dried distillers grains, high protein dried distillers grains, and corn bran), resulting in a total dietary fiber (TDF) range from <1% to 17.9%. Chapter 2 investigates microbial composition and predicted functional capacity in the jejunal, ileal, and colonic mucosa, while Chapter 3 focuses on the cecal mucosa and digesta. Overall, the inclusion of ICBF sources uniquely modulates the mucosal and luminal associated microbiota in each location. Increasing TDF resulted in a richer and more diverse microbiome. However, both fiber deprivation and high inclusion of IDF were associated with reduced microbial capacity for fiber fermentation and a greater metabolic capacity for degradation of mucins and other host-derived substrates. Meanwhile diets with more moderate fiber inclusion had increased abundance of beneficial bacteria like Bifidobacterium and Lactobacillus and an increased metabolic capacity for fiber fermentation. Simultaneously, transcriptomic analysis revealed upregulation of genes involved in mucin production, extracellular matrix remodeling, and antimicrobial peptides in diets which included ICBF. Conversely, fiber deprived diets resulted in microbial dysbiosis, impaired gastrointestinal morphology, and gene expression profiles associated with inflammation and tissue degradation. Chapter 4 examines the temporal adaptation of the fecal microbiome and total tract digestibility. Pigs fed diets which included ICBF exhibited more rapid microbiome stabilization compared to fiber devoid fed pigs. Additionally, moderate-high fiber diets had microbial functional profiles more capable of fermenting corn-derived hemicellulose, KEGG pathways associated with carbohydrate metabolism, and increased total short chain fatty acids. Despite the functional improvements of the microbiome, increasing the level of IDF in the diet did result in reduced total tract digestibility of gross energy, dry matter, IDF, and nitrogen. Collectively, this work highlights the complex interactions between dietary fiber, the gastrointestinal microbiome, and host physiology in swine. It provides insight into microbial community structure and function which may inform the development of future nutritional strategies including prebiotics, probiotics, postbiotics, or targeted dietary enzymes to improve fiber utilization in swine.
Table of Contents
PubMed ID
Degree
Ph. D.