[The effect of extrusion on the acceptability and digestibility of diets for growing dogs]

Eight German Shepherd pups, about 75 days old and a live weight of 11 kg at the beginning of the trial, were used to assay a diet formulated according to NRC, 1985 (Nutrient Requirements of Dogs). The diet was administered either pelletized (PD) or extruded (ED). Acceptability was evaluated through a cafeteria test, and diet utilization by a digestion trial, wherein dry matter (DM), crude protein (CP), ether extract (EE), crude fiber (CF), nitrogen-free extract (NFE), energy (E), Ca and P were considered. At the beginning and at the end of the digestibility trial, venous blood samples were obtained to run biochemical profiles. Results of the cafeteria test showed that extrusion-cooking improved significantly (P greater than 0.01) diet consumption, which for the ED was 512 and for the PD, 253 g/animal/day. Extrusion also improved significantly (P less than 0.01), the digestibility of DM, CP, EE, NFE and E, reaching values of 82.6, 75.2, 83.9, 90.8 and 83.6% for ED, and 68.0, 64.6, 76.7, 73.5 and 69.7 for PD, respectively. For CF, Ca and P, there was no effect (P greater than 0.05) of extrusion over digestibility. The biochemical profiles, only exhibited minor changes, all figures being considered within the normal range for puppies. It is concluded that extrusion-cooking significantly improves acceptability and biological utilization of normal diets for dogs.