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Title:Evaluation of select fiber and carbohydrate sources as functional ingredients in canine diets
Author(s):Traughber, Zachary T.
Director of Research:Cattai de Godoy, Maria R
Doctoral Committee Chair(s):Cattai de Godoy, Maria R
Doctoral Committee Member(s):Swanson, Kelly S; Stein, Hans H; Steelman, Andrew J; Fahey, Jr., George C
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Dietary fiber
ancient grains
Abstract:Dietary fiber is among the most popular ingredients for functional claims within companion animal nutrition and as such, has been highly researched in recent years. Various characteristics of fibers such as fermentability, viscosity, solubility, and physio-chemical structure results in different physiological effects including caloric dilution, blunting of postprandial responses, and modulation of gut microbiota and metabolites. These functionalities, alongside the humanization and premiumization of the pet food market, make fibers a prime target for microbial research and, subsequently, parameters of host health. However, the fermentation characteristics and health parameters of ancient grains as well as commercial yeast-derived beta-glucans is limited in current literature. The overall objective of this research was to evaluate various carbohydrate and fiber sources for use in canine diets, including ingredient chemical composition and fermentation profiles, and their effects on apparent total tract digestibility (ATTD), fecal characteristics, microbial community and metabolites, post-prandial blood metabolite kinetics, and overall potential immune modulatory effects. Our first aim was to establish the differences between fiber quantification methods and their subsequent effect on metabolizable energy calculations. We evaluated diets of client-owned, osteoarthritic animals that were derived from previous research. Our second aim was to establish nutrient and fermentative profiles using canine fecal inoculum in a three-stage, batch, in vitro model. We evaluated a variety of novel ancient grains and legumes. Our third aim was to determine the effects of these ancient grains in vivo on apparent total tract digestibility, fecal characteristics, microbial populations and fermentative end-products, and post-prandial glucose and insulin responses. We evaluated a 40% inclusion of four novel ancient grains in extruded diets compared to an extruded rice-based control diet and a six-hour post-prandial glucose and insulin response was generated on the final day of each period. Our fourth aim was to determine the effects of a purified yeast-derived beta-glucan commercial product in vivo on apparent total tract digestibility, fecal characteristics, microbial community and fermentative end-products, and immunological parameters following a vaccination challenge. We evaluated a 150-ppm inclusion both in the formulation of a retorted diet, as well as top-dressed on a control diet and challenged the immune system with a canine Bordetella bronchiseptica vaccination. In our first aim, we determined that fiber content of canine diets measured via crude fiber or total dietary fiber differed, which have a significant impact on metabolizable energy (ME) calculation of pet foods. Presently, the Association of American Feed Control Officials (AAFCO) only requires crude fiber to be reported on the guaranteed analysis of complete and balanced commercial diets, which typically results in an underestimation of the fiber content and ME of these diets. In our second aim, we determined that both ancient grains and legumes are nutrient-rich ingredient sources, each providing complex profiles of dietary fibers, sugars, and proteins. Pseudocereals and minor cereal grains (i.e., under-utilized cereal grains) contain the highest concentrations of free and hydrolyzed glucose, respectively, whereas legumes contain predominantly sucrose and stachyose. Ancient grains began displaying large increases in fermentative end-products (e.g. volatile fatty acids and gas production) after 6 h and, overall, had fermentation profiles that did not differ from beet pulp. In vitro, legumes displayed a slower fermentative profile, which may have implications on the ratios of saccharolytic vs. proteolytic fermentation towards the distal colon in vivo. However, this needs to be tested. In our third aim, we demonstrated similar beneficial effects on fermentation in vivo of select ancient grains from aim two. Apparent total tract digestibility of macronutrients were consistently greatest (P < 0.05) in diets containing rice (CON) or white proso millet (WPM), and lowest (P < 0.05) in diets containing quinoa or oat groats (OG) while digestible and metabolizable energy were not affected (P > 0.05) by ancient grain inclusion. The addition of ancient grains beneficially shifted the fecal microbial population, with increases in the relative abundances of butyrogenic bacteria observed for OG and reduction in Fusobacteriaceae for both diets containing amaranth (AM) and OG when compared with CON. These ingredient sources can safely be included up to 40% of dietary matrix with no detrimental effects on host health or macronutrient digestibility. In our fourth and final aim, we determined that a 150-ppm inclusion of the commercial yeast beta-glucan product had no detrimental effects on ATTD, and fecal characteristics and metabolites were unaffected. Inclusion of the beta-glucans in the retorted diet formulation resulted in a greater (P < 0.05) digestible energy and ATTD of dry matter and crude protein than the control diet, with top-dressing beta-glucan being an intermediate. Immunological parameters were unaffected as well and, thus, the effects of the retorting process on the stability of this yeast-based beta glucan ingredient cannot confidently be reported. This research provides data for the present discussions on fiber content in guaranteed analysis label requirements of complete and balanced diets. This research established in-depth nutrient profiles and fermentation characteristics of novel carbohydrate and fiber ingredients and demonstrated beneficial effects on host health and fecal microbiome. Together, these findings provide knowledge on fibrous ingredient sources with the most promising beneficial effects observed in ancient grains, specifically, amaranth and oat groats. However, further research is needed to determine the potential health benefits of these fiber sources in diets for weight management or obese dogs, as well as potential synergistic effects of fiber blends for use in canine nutrition.
Issue Date:2020-08-31
Rights Information:Copyright 2020 Zachary Tyler Traughber
Date Available in IDEALS:2021-03-05
Date Deposited:2020-12

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