Fecal Bypass Macronutrients Impact Stool Quality in Dogs and Cats while Species Differentially Impacts Nutrient Digestibility

Abstract

ObjectivesEvaluate the impact of animal and food characteristics on apparent digestibility and stool quality in dogs and cats.MethodsHealthy dogs and cats were housed in environments promoting social interaction, having access to natural light that varied with season and opportunity to exercise. Animals were fed to maintain healthy body weight and health was monitored through regular clinical and physical checkups. Across two decades, 11,963 studies examining apparent nutrient digestibility were conducted using dry and canned foods. Studies were carried out under IACUC approved protocols. Proportional digestibility for dry matter, fat, nitrogen‐free extract, and fiber was calculated as difference between analyzed amounts in the food versus feces. Stool quality was evaluated using a standardized 5‐point system. Relations between animal characteristics (age, stool quality) and digestibility, as well as interactions between macronutrients that bypassed digestion, were evaluated with linear mixed models. Results significant at p≤0.05 are reported.ResultsIn dogs, there was a negative association between age and linear coefficients for fiber, dry matter, carbohydrate, and fat digestibility but a positive association between age and quadratic coefficients for carbohydrate and dry matter digestibility. In cats, there was positive association between age and linear coefficients for protein and energy while there were negative associations between age and the linear coefficient for fiber and the quadratic coefficient for protein. Maximum protein digestibility occurred at approximately 14 years in dogs and at 8 years in cats; maximum crude fiber digestibility in dogs and cats occurred at 1 year. In both species, high fecal protein and low fecal fiber predicted decreased stool quality, and fecal fiber was positively associated with fecal protein and fat.ConclusionsAging in dogs and cats differentially impacted nutrient digestibility; protein and energy digestibility had a positive linear association with age in cats, while dry matter, carbohydrate, energy and fat digestibility had a negative linear association with age in dogs. In both species, fiber digestibility linearly decreased with increasing age. Undigested fecal fiber was associated with improved stool quality while fecal protein was detrimental. Intriguingly, the impact of fecal bypass macronutrients on stool quality was significantly greater in cats than dogs. This is the largest investigation to date evaluating associations between age and macronutrient digestibility in dogs and cats, and supports the development of diets to optimize health throughout the lifespan.Support or Funding InformationHill's Pet Nutrition, Inc. Topeka, Kansas, USAThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.