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Title:Evaluation of novel plant- and yeast-based protein sources on nutrient digestibility, fecal metabolites, and taurine status in dogs and cats
Author(s):Reilly, Lauren M.
Director of Research:de Godoy, Maria R. C.
Doctoral Committee Chair(s):de Godoy, Maria R. C.
Doctoral Committee Member(s):Swanson, Kelly S.; Fahey, Jr., George C.; Parsons, Carl M.; Stein, Hans H.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Plant Protein
Abstract:The rising demand for alternative protein sources in pet diets has driven the increased use of plant-based protein sources in diet formulations. However, the novelty of these ingredients has led to a paucity of information regarding digestibility and acceptability of these ingredients by dogs and cats. The overall objective to this research was to evaluate plant-based protein sources for use in canine and feline diets. The first aim was to characterize the plant-based ingredients by determining chemical composition and standardized amino acid digestibility, as well as to describe the protein quality using digestible indispensable amino acid scores. The second aim was to determine the effects of green lentils (GLD), garbanzo beans (GBD), peanut flour (PFD), and dried yeast (DYD) on apparent total tract macronutrient digestibility (ATTD), fecal fermentative end-products, and microbiota composition in dogs compared with a poultry by-product meal diet (CON). The third aim was to evaluate changes in taurine status and circulating essential and non-essential amino acids in dogs fed a diet containing 45% green lentil diet (GLD) compared with a traditional poultry by-product meal-based diet (CON). The fourth and final aim was to evaluate effects of graded levels of garbanzo beans (GB; 0, 7.5, 15, or 30% raw or 30% cooked) on macronutrient ATTD, fecal fermentative end-products, and microbiota composition in cats. In the first aim, the analyzed ingredients were categorized into pulses, protein concentrates, and plant by-products based on chemical composition. The pulse ingredients (green lentils, yellow peas, garbanzo beans, black bean grits, and navy bean powder) contained approximately 20% crude protein, and had methionine or tryptophan as the first-limiting amino acid compared with National Research Council (NRC) recommended allowances and Association of American Feed Control Officials (AAFCO) recommended values. The protein concentrates included soy protein concentrate, faba bean protein, pea protein, potato protein, and dried yeast. Standardized amino acid digestibility of amino acids were high (88.0-96.1%), methionine and tryptophan were the first-limiting amino acids for these ingredients. Lastly, the plant by-products (peanut flour, corn gluten mean, soy flake, soybean meal) were more variable in terms of chemical composition and amino acid profiles than the previous two groupings. Lysine was determined to be the first-limiting amino acid for both peanut flour and corn gluten meal whereas methionine was the first-limiting amino acid for soy flake and soybean meal. In the second aim, no negative impacts were observed in the macronutrient ATTD, fecal scores, or serum metabolites of dogs fed diets containing legumes or yeast. Dogs fed the legume or yeast diets had greater (P < 0.05) fecal short-chain fatty acid concentration compared with the poultry by-product meal (control) diet. Additionally, the dogs fed the dried yeast diet had greater (P < 0.05) fecal butyrate concentration than dogs fed the other diets. Additionally, dogs fed DYD had a different microbial composition compared with dogs fed the other diets, with the lowest relative abundance (P < 0.05) of Proteobacteria. Dogs fed CON and PFD had similar fecal microbial communities in contrast with dogs fed the other diets. In the third aim, dogs fed GLD did not have any differences in plasma or whole blood taurine concentrations compared with dogs fed CON for 90 days. Dogs fed CON had increased fecal lithocholic acid (LCA) concentrations (P < 0.05), which strongly correlated with the microbial taxa Eubacterium and Streptococcus alactolyticus, compared with dogs fed GLD. In the final aim, cats fed 30% cooked GB had the lowest (P < 0.05) apparent total tract dry matter and organic matter digestibility compared with the other diets. The 0% GB had the highest (P < 0.05) relative abundance of Firmicutes and Fusobacteria but the lowest (P < 0.05) relative abundance of Proteobacteria compared with the GB-containing diets. No detrimental effects were observed in the serum metabolites, fermentative end-products, or fecal scores in cats fed any of the diets. This research provided insight on the use of either legumes or yeast at high inclusion levels in canine and feline diets. The evaluation of these ingredients in terms of macronutrient composition, amino acid profiles, ATTD, fermentative end-products, and health parameters can impact how these proteins are used in formulations. Results of this research demonstrate the inclusion of these plant- and yeast-based proteins are viable as protein sources in the pet food industry but the legume and pulse ingredients should be included with complementary protein sources, such as cereal grains or animal protein sources, to provide all of the essential amino acids to dogs and cats.
Issue Date:2020-11-29
Rights Information:Copyright 2020 Lauren Reilly
Date Available in IDEALS:2021-03-05
Date Deposited:2020-12

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