Digestibility of dry extruded food in adult dogs and puppies

The aging process in cats and dogs is mainly influenced by genetics, nutrition, and the environment to which the animals are submitted, among other factors. Animal development is associated to changes in the physiological and metabolic systems; however, such changes are not completely elucidated in companion animals (Hayek and Davenport, 1998). As animal’s age, the intestinal microbiota and morphology, as well as the production of digestive enzymes and hormones are modified, influencing digestibility (Fahey et al., 2008). According to Meyer et al. (1940), amylase, trypsin, and lipase activities in the duodenal juice are reduced with age. However, Gilham et al. (1993), in a study with Labrador Retriever puppies with twelve or twenty weeks of age, did not find any statistically significant influence of age on nutrient digestibility. Taylor et al. (1995) also postulated that the reduction of enzyme production as a consequence of age does not affect nutrient digestion and absorption because the mammalian gastrointestinal tract (GIT) has a