Effect of soya hulls on diet digestibility, palatability, and intestinal gas production in dogs

The objective of this study was to evaluate the palatability, coefficients of total tract apparent digestibility (CTTAD) of food nutrients, metabolizable energy (ME), faecal characteristics (FC), and intestinal gas production (IGP) of dog foods containing different fibre sources. Three experiments were carried out. In experiment 1, a reference diet (REF), and diets containing 40 g/kg, 80 g/kg, 120 g/kg, and 160 g/kg soya hulls (SH); 130 g/kg sugarcane (SC); 160 g/kg beet pulp (BP); or 120 g/kg cellulose (CE) were tested. Total food digestibility was evaluated in eight dogs distributed according to an 8 × 8 Latin square experimental design. In experiment 2, palatability was evaluated in five paired comparisons. Experiment 3 measured IGP according to a completely randomized experimental design in 12 dogs fed diets containing 160 g/kg SH or not. The inclusion of fibre sources did not affect diet palatability. Increasing SH dietary levels linearly reduced CTTAD and ME content and increased faecal output (FO, P < 0.05). The reference diet presents higher nutrient CTTAD (P < 0.05), ME content, and faecal pH and lower FO compared with the diets containing soya hulls (SHG) and with those containing other fibres (OFG − SC, BP, and CE). Faecal dry matter content of the SHG was lower than REF, SC, and CE, but higher than BP (P < 0.05). Faecal sialic acid content and faecal score were not different among the treatments (P < 0.05). Total dietary fibre, and insoluble and soluble fibre intakes were negatively correlated (P < 0.05) with nutrient CTTAD and faecal output. Sialic acid content, faecal score and intestinal gas area (IGA) were not different among treatments. However, dogs fed the diet with 160 g/kg SH presented larger IGP area. Because SH presented similar results as typical fibre sources, it can be added to dog foods.