The replacement value of sorghum and maize with or without supplemental enzymes for rice in extruded dog foods

The replacement value of sorghum and maize for rice in extruded dog foods was studied. The diets contained 552 g sorghum/kg diet, 535 g maize/kg diet and 521 g rice/kg diet. The addition of a feed enzyme product containing a cocktail of carbohydrates to the sorghum- and maize-based diets was also tested, with the enzyme being sprayed on to the dry diets at feeding at a level of 1000 ml/t. The experiment lasted 13 days with faecal collections occurring on the final 5 days. Measurements taken were: faecal score (1 indicating hard faeces, 5 indicating diarrhoea), macronutrient digestibilities, faecal pH and volatile fatty acid (VFA) and lactate concentrations. The coefficient of total tract apparent digestibility (CTTAD) for starch was complete in all diets. The CTTAD of fat, protein and energy in the sorghum- and maize-based diets was lower (P<0.05) compared to the rice based diet, and were not increased (P>0.05) by enzyme addition. Consequently, the digestible energy (DE) content of the rice-based diet was 0.3-0.8 MJ DE/kg DM higher (P<0.001). The faecal score of dogs fed rice was higher (P<0.05) than their counterparts fed sorghum and maize, with the enzyme increasing faecal score (P<0.05) and making it equivalent to that of dogs fed the rice-based diet (P>0.05). The faeces of dogs fed rice had a higher pH (P<0.05) compared to dogs fed the sorghum- and maize-based diets. The improved quality of faeces seen in dogs fed sorghum and maize, balanced by only minor decreases in digestibility and DE content, suggests that maize and sorghum are suitable alternatives to rice as the primary cereal in extruded dog foods.