Digestibility and metabolisable energy in high-ash poultry meal and plant protein ingredients for dogs

Using the substitution method and extruded diets, the metabolisable energy (ME) and digestible nutrient contents of soybean meal (SBM), poultry by-product meal with high ash content (PBMha), micronised soybean meal (MSM), and corn gluten meal (CGM) were determined for dogs. A complete and balanced control diet (CD) was formulated. Test diets were prepared by mixing 70% of the CD with 30% of the protein source in evaluation, according to the substitution method requirements. Due to its high fat content, the MSM diet was formulated with 85% of the CD and 15% of MSM to obtain adequate extrusion. Thirty-five Beagle dogs (7 per diet) were used to evaluate the total tract apparent digestibility (TTAD) of each diet, by the total collection of faeces method. Results were applied to calculate the ingredient TTAD and digestible nutrients content. Data were analysed in a completely randomised design and submitted to ANOVA and Tukey test (p < 0.05). The TTAD of DM, OM, CP, and gross energy were higher for CGM (p < 0.05). The TTAD of CP was similar for SBM and MSM, whose values were higher than for PBMha (p < 0.05). Faeces production was higher for dogs fed the SBM diet and PBMha, and faecal DM was lower for dogs fed the SBM diet. The results indicate variable TTAD among protein sources, with vegetable protein sources generally being more digestible than PBMha.