Raw and rendered animal by-products as ingredients in dog diets

Approximately 25 to 40% of the DM in premium dog diets is animal by-product. However, limited information is available regarding the composition and digestibility of these by-products, especially small intestinal digestibility. The effects of raw and rendered animal by-products incorporated into dog diets on nutrient digestion at the ileum and in the total tract were studied in this experiment. Diets fed contained various animal by-products including a rendered beef meat and bone meal (RMBM); fresh beef (FB); poultry by-product meal (PBPM); fresh poultry (FP); a plant-based control protein source, defatted soy flour (DS); and an animal-based control protein source, dehydrated whole egg (WE). The diets were extruded and kibbled. By-products varied widely in concentrations of OM, CP, amino acids, and fat. Nutrient intakes were numerically higher for FB than for all other treatments. All nutrient intakes were higher (P < .03) for the FB treatment than for the RMBM treatment. Digestibilities of DM, OM, CP, fat, and GE at the ileum were higher (P < .06) when dogs were fed diets containing FP than when fed diets containing PBPM. Amino acids were highly digestible at the ileum; however, digestibilities of all amino acids except cystine were higher (P < .04) for the diets incorporating FP vs PBPM. Total tract digestion was different among treatments for DM (P < .02), OM (P < .01), and GE (P < .02), and diets containing animal by-products were similar in total tract digestibility, greater than the DS control, and lower than the WE control. Rendering of poultry, but not beef, seemed to have a slight negative influence on small intestinal, but not total tract, digestibility by dogs.