Determination of the in vitro digestibility and nutrient content of commercial premium extruded foods with different types of protein content for adult dogs

The purpose of this study was to compare the in vitro digestibility levels and chemical compositions of commercial extruded dry-type adult dog foods with different types of protein contents [fish meat (F-dog foods) (n = 7), lamb meat (L-dog foods) (n = 9), or poultry meat (P-dog foods) (n = 8)]. The in vitro digestion values of premium commercial dog foods were examined at three stages: gastric digestion, small intestine digestion and large intestine digestion/fermentation. The metabolisable energy (ME), crude protein (CP), starch, diethyl ether extract (EE) and ash contents and the in vitro cumulative gas production values of all the premium dog foods differed significantly among the commercial brands in the same category (F-, L- or P-dog foods) (P < 0.05). The crude fibre (CF) and the CP/1 000 kcal ME values of the F- and P-dog foods demonstrated a significant difference among the commercial brands (P < 0.05). The organic matter disappearance (OMd) values of the L-dog foods showed a significant difference among the commercial brands (P < 0.05); but the OMd values of the F- and P-dog foods did not differ among the commercial brands (P > 0.05). The average values of the OMd for the F-dog foods were more rapid than the average for the L- and P-dog foods, in the evaluation of all the foods (P = 0.001). Besides, the price of the L-dog foods was positively correlated with the OMd and CP of the L-dog foods; however, it was negatively correlated with the NFE (nitrogen free extract) and CHO (total carbohydrates) of the L-dog foods (P < 0.05). The CP values of the L-dog foods were positively correlated with the OMd values (P < 0.05). Although price is an important determinant of food quality in the L-dog foods, it is not in the F- and P-dog foods. In the general evaluation of all the dog foods, there was no correlation among the food price and the digestibility and the nutrient content for all of the premium dog foods. The present study indicated that the energy, nutrient matter and digestibility of premium dog foods changed with the change in the variety and the amount of the feedstuffs. The digestibility of the dog foods with the fish meat were higher than those of the other dog foods. The amount of protein that an adult dog will receive with 1 000 kcal of DM (dry matter) consumption of premium dog foods with fish meat and chicken meat, varied among the brands. This point showed the need to pay attention to the food consumption amount of the dogs and the energy-protein balance in their diets, especially dog foods with fish meat and chicken meat.