Date of Graduation
5-2025
Document Type
Thesis
Degree Name
Bachelor of Science in Agricultural, Food and Life Sciences
Degree Level
Undergraduate
Department
Animal Science
Advisor/Mentor
Maxwell, Charles V.
Committee Member
Tsai, Tsungcheng
Second Committee Member
Powell, Jeremy G.
Third Committee Member
Zhao, Jiangchao
Abstract
Colibacillosis, a bacterial infection caused by pathogenic Escherichia coli, is the leading cause of postweaning diarrhea (PWD) in food-producing pigs. This study aimed to investigate the effectiveness of dietary fiber sources and a stimbiotic (a feed additive that enhances fiber fermentability by stimulating fiber-degrading microbiota in the gut) on the sustainability of an enterotoxigenic Escherichia coli (ETEC) challenge, specifically regarding the F18 strain. A total of 216 piglets were blocked (n = 8) by weaning BW and randomly assigned to one of four dietary treatments, including corn-SBM-wheat middling-based control diet (CC), high-fiber diet (HF: 5.0, 3.8, and 2.5% sugar beet pulp and 4.0, 3.0 and 2.0% soy hulls for phases 1, 2, and 3, respectively), CC plus 0.01% stimbiotic (CS: Signis, ABVista, Marlborough, United Kingdom), and HF plus 0.01% stimbiotic (FS). Pigs were fed a four-phase feeding regimen: Phase 1 (d0-9), Phase 2 (d9-16), Phase 3 (d16-22), and Phase 4 (d22-41). Dietary treatments were provided from weaning (d0) to d22, and a common diet was fed from d22 to trial completion. On day 5 of postweaning, all pigs were orally inoculated with 10 mL of F18 ETEC (108 CFU/mL). One median BW pig from each pen was selected for fecal sampling on days 0, 2, and 7 postchallenge. Samples were used to quantify the live E. coli using a 3M Petrifilm E. coli/Coliform Count Plate (3M Food Safety, St. Paul, MN), and the virulence genes of the isolate were identified using multiplex PCR. Colony-forming-count was log-transformed. The data on quantitative traits were analyzed using a MIXED procedure in SAS, and binary data were analyzed using the Frequency procedure in SAS (Cary, NC). Total E. coli counts did not differ between treatments. Out of 466 colonies selected, the majority (84.12%) lacked the virulence genes tested. In comparison, colonies expressing the F18 gene (n = 53) also exhibited the heatlabile (LTb) toxin and heat-stable (STb and STaP) toxin genes simultaneously. In addition, in colonies that did not express the F18 gene, 21, 19, and 21 of those colonies co-expressed LTb, STb, and STaP genes, respectively. Pigs fed high-fiber diets had a lower percentage of F18- encoded E. coli (6.37% vs 18.09%, P < 0.001) compared to those fed low-fiber diets. In comparison, pigs fed stimbiotic had a higher percentage of F18-encoded E. coli (13.67% vs. 7.98%, P < 0.001) in fecal samples than pigs fed no stimbiotic. Pigs fed CC and HF had similar percentages of F18-encoded E. coli (P = 0.164). In contrast, pigs fed FS and CC had a lower percentage of F18-encoded E. coli than pigs fed CS (6.76% and 11.59% vs. 21.54%, P < 0.001 and P = 0.088, respectively). The results of this study demonstrate that high-fiber diets and stimbiotic impact the percentage of virulence genes expressed in live E. coli colonies of fecal samples differently, suggesting that a different mechanism may be involved in restoring ADG in pigs challenged with ETEC.
Keywords
enterotoxigenic Escherichia coli; fiber; stimbiotic; virulence genes; nursery pigs
Citation
Shirer, E. I. (2025). Effect of Fiber and Stimbiotic on Growth Performance and the Gut Microbiome in Pigs Challenged with F18 Enterotoxigenic Escherichia coli (ETEC). Animal Science Undergraduate Honors Theses Retrieved from https://scholarworks.uark.edu/anscuht/80
