| Ten ileally cannulated mature female dogs were used in three experiments to evaluate the effects of processing conditions on nutrient loss and digestibility of a canned dog food. A beef-based diet was retorted and analyzed for nutrient contents. Lyophilized and frozen diets were used as the control for Exp.1 and 3, respectively. In Exp. 1, the diet was retorted at 118°C/77 min, 124°C/58 min, and 127°C/52 min. All combinations resulted in a sterilizing value (F0) of 8. In Exp. 2, the diet was retorted at 124°C for 58, 67, 75, and 83 min. In Exp. 3, the diet was retorted for 75 min at 118, 121, 124, and 127°C.;All processing conditions used in the present studies decreased the majority of the nutrient content in the retorted diets. Exp. 1. Diets retorted at 124°C/58 min had the lowest (P < .05) total tract digestibility for dry matter (DM), organic matter (OM), starch, and gross energy. This diet also had the lowest (P < .05) large intestinal OM and crude protein (CP) digestibility. Exp. 2. Large intestinal digestibility for DM, OM, CP, and gross energy decreased linearly (P < .05) with increasing retorting time. Exp. 3. Real digestibility for gross energy and total tract digestibility for CP and gross energy decreased quadratically (P < .05) with increasing retorting temperature. Heal, large intestinal, and total tract digestibilities for DM, OM, CP, gross energy, and starch of the retorted diets were lower (P < .01) than the frozen diet.;An inverse relationship (R2 = 0.92, 0.97, and 0.85 for Exp. 1, 2, and 3, respectively) was observed between the ratio of available to total lysine, and increased retorting with a tendency to decrease as retorting time or temperature increased. Available lysine decreased 0.6%/min by increasing retorting time at 124°C (Exp. 2), and 2.0%/°C at 75 min (Exp. 3). Heal lysine digestibilities for the retorted diets were lower (P < .01) than the non-retorted diets.;Processing conditions, at least defined within these studies, reduced nutrient digestibility and availability with more sensitivity to retorting temperature than retorting time. |
