This experiment evaluated the effects of including the enzyme β-mannanase in dog diets based on poultry by-product meal (PBM) or soybean meal (SBM). The second objective was to evaluate three methods for determining energy and nutrient digestibility values in diets fed to dogs: total fecal collection (TFC), use of acid-insoluble ash (AIA) or crude fiber (CF) as a marker. Eight dogs were fed two diets with PBM as the major protein source and two diets based on SBM as the major protein source. Within each protein source, one diet contained no β-mannanase and one diet contained 0.01% β-mannanase.

There were interactions between protein source and β-mannanase. Supplementation of β-mannanase increased apparent total tract digestibility (ATTD) of nutrients and energy and metabolizable energy (ME) and also reduced fecal production in the diet with SBM but not in the diet that contained PBM. There was an interaction between digestibility calculation procedure and protein source. The use of AIA overestimated ATTD of the diets containing PBM, but digestibility values estimated based on TFC and CF were not different. Dogs fed diets containing SBM produced more feces with greater moisture content and less pH compared with dogs fed a PBM diet. Addition of 0.01% β-mannanase increased the digestibility and ME content of the diets containing SBM but did not improve fecal texture.

Values for ATTD of energy and nutrients in diets containing SBM are not different if calculated based on TFC, AIA or CF, but use of AIA may result in an overestimation of values for ATTD of energy and nutrients in diets containing PBM.

Source : A.P. Félix et al., 2012. The effect of β-mannanase on the digestibility of diets with different protein sources in dogs determined by different methodologies. J Anim Sci online May 2012. doi: 10.2527/jas.2011-4222