Effects of yeast products and dietary fibers on gastrointestinal health outcomes and microbiota populations of dogs and cats

De La Guardia Hidrogo, Vanessa Michelle

Permalink

https://hdl.handle.net/2142/129180 Copy

Description

Title

Effects of yeast products and dietary fibers on gastrointestinal health outcomes and microbiota populations of dogs and cats

Author(s)

De La Guardia Hidrogo, Vanessa Michelle

Issue Date

2025-03-20

Director of Research (if dissertation) or Advisor (if thesis)

Swanson, Kelly S

Doctoral Committee Chair(s)

Swanson, Kelly S

Committee Member(s)

• Fahey, Jr, George C
• Dilger, Ryan N
• Stein, Hans H

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• companion animals
• nutrition
• brewers yeast
• dietary fiber

Abstract

Over the past few decades, interest in functional ingredients has increased, leading to their broad application in pet foods. This trend is largely driven by the growing commitment of owners to their pets' health and well-being. Functional ingredients are incorporated into pet diets to provide health benefits that extend beyond basic nutrition, supporting areas such as gastrointestinal health and immune function. Given the high costs and time constraints associated with traditional animal experiments, the use of both in vivo and in vitro models offers a more efficient approach for the preliminary evaluation of the functional benefits of these ingredients. The objective of this dissertation was to evaluate the effects of select functional ingredients on gastrointestinal health outcomes and microbiota populations of dogs and cats. The aim of the first experiment was to evaluate the effects of a yeast-enriched functionalized canola meal (FCM) on apparent total tract digestibility (ATTD) of diets and their effects on the fecal quality, metabolite concentrations, and microbiota populations, and immune function of healthy adult dogs. Twelve adult female beagle dogs (body weight = 7.6 ± 0.7 kg; age = 5.8 ± 1.3) were used in a replicated 4 × 4 Latin square design to test the following dietary treatments: 1) FCM only (no yeast inclusion), 2) FCM + low yeast dose, 3) FCM + medium yeast dose, and 4) FCM + high yeast dose. All treatments were top-dressed onto the basal diet at a rate estimated to be 1% of daily intake (as-is basis). Supplementation with yeast-enriched FCM had no effect on the ATTD of macronutrients or energy or the fecal characteristics, metabolite concentrations, and microbiota populations or immune function of healthy adult dogs. The aim of the second experiment was to evaluate the effects of extruded diets containing FCM enriched with different levels of dried yeast on the ATTD of diets and their effects on fecal characteristics and microbiota, skin measures, and serum oxidative stress markers of adult dogs Twelve adult female beagle dogs (body weight = 9.75 ± 0.83 kg; age = 6.2 ± 1.6 yr) were used in a replicated 4 × 4 Latin square design to test four extruded kibble diets: 1) CTRL (containing no FCM or yeast), 2) FCM + low yeast dose (LY), 3) FCM + medium yeast dose (MY), and 4) FCM + high yeast dose (HY). Supplementation with yeast-enriched FCM tended to increase fecal output (as-is: P<0.07; dry matter: P<0.08). The ATTD of fat tended to be lower (P<0.06) in diets containing yeast-enriched FCM. The ATTD of other nutrients and energy were unaffected by treatments. Fecal indole and total phenol and indole concentrations were lower (P<0.05) in dogs fed LY than in those fed MY. Other fecal characteristics, metabolite concentrations, and bacterial alpha and beta diversity measures were not affected by treatment. The relative abundance of Eubacterium brachy was greater (P<0.04) in MY and HY diets, while Ruminococcus gnavus tended to be lower (P<0.10) in HY and MY diets, and Peptoclostridium tended to be greater (P<0.10) in CTRL than the other diets. Also, skin measures and oxidative stress markers were not affected by treatment. The aim of the third experiment was to determine the in vitro fermentation characteristics of common dietary fibers using fecal inoculum from dogs supplemented with a dried brewer’s yeast product. Sixteen healthy adult dogs were acclimated for 7 d and then randomly assigned to a control diet (CTRL) containing no yeast or a dried brewer’s yeast-containing diet (BY; n=8/group) for a 21-day period. Fecal samples collected at the end of the treatment period were frozen in 20% glycerol solution. Fecal samples were then thawed and used as inoculum for in vitro fermentation of beet pulp, pectin (positive control), and cellulose (negative control) over 0, 6, 12, or 18 h, with pH, short-chain fatty acid (SCFA) production, and microbiota measured at each time point. Fermentation patterns differed among fiber substrates over time (P<0.01). Specifically, pectin was highly fermentable, beet pulp had moderate fermentation, and cellulose was minimally fermented, as indicated by SCFA production (P<0.01) and pH changes (P<0.01). Inoculum source also modified fermentation characteristics, with tubes inoculated with BY having a greater (P<0.05) increase in SCFA production and larger (P<0.05) pH change than those inoculated with CTRL. Also, tubes inoculated with BY had a greater increase in the relative abundances of SCFA-producing bacteria such as Catenibacterium and Collinsella, while reducing the relative abundances of Fusobacterium, Streptococcus, and Sutterella. Other SCFA-producing bacterial taxa were also affected by inoculum source, but the results varied within fiber substrate. The aim of the fourth experiment was to evaluate the fermentation characteristics of acacia fiber, inulin, pectin, and cellulose using an in vitro fermentation system and canine fecal inocula. Triplicate samples of each fiber were fermented for 0, 6, 12, and 18 h. Fiber×time interactions (P<0.01) were observed for pH change, gas and SCFA production, and microbiota populations. Pectin and inulin had the greatest (P<0.01) gas and SCFA production, inulin demonstrated the largest (P<0.01) pH reduction, followed by pectin. Acacia fiber resulted in smaller pH reductions but greater (P<0.01) SCFA production than cellulose. Bacterial alpha diversity increased (P<0.01) during acacia fiber fermentation but decreased (P<0.01) during inulin fermentation. Beta diversity analyses showed distinct (P<0.01) bacterial community clustering by fiber type. The relative abundances of approximately 40 bacterial genera were affected by fiber×time interactions. Specifically, tubes containing acacia fiber had a greater (P<0.01) increase in Bacteroides, Faecalibacterium and Ruminococcus torques group than other fibers. Inulin tubes had a greater (P<0.01) increase in Prevotella, while pectin tubes had a greater (P<0.01) increase in Bifidobacterium than other fibers. The aim of our last experiment was to evaluate the fermentation characteristics of acacia fiber, inulin, pectin, and cellulose using an in vitro fermentation system and feline fecal inocula. Again, fiber×time interactions (P<0.01) were observed for pH change, gas and SCFA production, and microbiota populations. Pectin and inulin tubes had greater (P<0.01) gas production than acacia fiber and cellulose tubes. Inulin and pectin tubes exhibited the greatest pH reductions (P<0.01), followed by acacia fiber, which had a smaller pH reduction than cellulose after 12 hours. Total SCFA production, including acetate, propionate, and butyrate, was greater (P<0.01) in pectin and inulin tubes than acacia fiber and cellulose tubes. However, acacia fiber tubes had greater (P<0.01) total SCFA, acetate, and propionate production than cellulose tubes after 12 h. Bacterial alpha diversity increased (P<0.01) in acacia fiber tubes but decreased (P<0.01) in inulin and pectin tubes, while beta diversity showed distinct clustering of bacterial communities among fibers (P<0.01). The relative abundances of predominant (% sequences > 1%) bacterial genera were affected by significant fiber×time interactions. Specifically, acacia fiber tubes had a greater (P<0.01) increase in Bacteroides, Blautia, and Faecalibacterium than other tubes. Inulin and pectin tubes also had a greater increase (P<0.01) in SCFA-producing bacteria. Our findings suggest that the effects of yeast-enriched FCM are largely dependent on the ratio of yeast to FCM, with larger effects observed at greater yeast inclusion levels. Yeast-enriched FCM may positively influence stool quality, fecal metabolites, and microbiota when incorporated into extruded diets. Additionally, the in vitro experiments demonstrated the influence of dried brewer's yeast and various fiber sources on microbial composition and fermentation dynamics. Fiber fermentation profiles vary widely and can significantly affect canine and feline microbiota community composition and activity. Acacia fiber is moderately fermentable, promoting bacterial diversity and beneficial shifts in microbiota composition and activity while producing minimal gas. In contrast, pectin and inulin exhibit high fermentability, with significant effects on gut microbiota populations and high gas production, whereas cellulose is poorly fermentable resulting in minimal effects on microbial composition and activity. Thus, inclusion of yeast-based ingredients and moderately fermentable fibers in pet foods may promote gastrointestinal health.

Graduation Semester

2025-05

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129180

Copyright and License Information

© 2025 Vanessa M. De La Guardia Hidrogo

Owning Collections