Abstract
Human-grade dog foods are now available and increasing in popularity, but little research has been conducted to test the digestibility of these foods. The objective of this experiment was to determine the true nutrient and amino acid (AA) digestibilities of human-grade ingredient-based dog foods using the precision-fed cecectomized rooster assay. Six commercial dog foods were tested, including the Beef & Russet Potato (BRP), Chicken & White Rice (CWR), Fish & Sweet Potato (FSP), Lamb & Brown Rice (LBR), Turkey & Whole Wheat Macaroni (TWM) and Venison & Squash (VSR) formulas provided by Just Food For Dogs (Irvine, CA). Before analysis, all diets were lyophilized and ground. A precision-fed rooster assay utilizing cecectomized roosters was conducted to determine the true nutrient digestibility and standardized AA digestibilities of the diets tested. Conventional roosters were used to determine the nitrogen-corrected total metabolizable energy (TMEn) of the diets. All animal procedures were approved by the University of Illinois Institutional Animal Care and Use Committee prior to experimentation. The substrates and rooster excreta were analyzed for macronutrient profile and AA composition. All data were analyzed using the Mixed Models procedure of SAS 9.4. In general, all diets tested were highly digestible. Dry matter digestibility was similar among CWR, LBR and TWR diets, and greater (P < 0.0001) than that of FSP and VSR diets. Organic matter digestibility was highest (P = 0.0002) for CWR and lowest (P = 0.0002) for VSR. TMEn value was highest for BRP. For the majority of indispensable AA, digestibilities were greater than 85%, with some being greater than 90%. Although statistical differences were observed among diets, they all performed very well. The diets tested had very high AA digestibilities, being digested at levels exceeding that usually observed with extruded diets.