Evaluation of low-oligosaccharide, low-phytate whole soybeans and soybean meal in canine foods

Eight mature dogs (19.3 ± 0.1 kg) were used in an experiment to compare the effects of feeding soybeans containing low concentrations of oligosaccharides and phytate on nutrient availability in complete foods fed to dogs. All foods were formulated to be isonitrogenous and contained low-oligosaccharide, low-phytate soybean meal (LLM); conventional soybean meal (SBM); low-oligosaccharide, low-phytate whole soybeans (LLB); or conventional whole soybeans (WSB) as the protein source. Daily DMI averaged 287 ± 4 g/d. Fecal outputs were greatest for LLB and WSB, averaging 48.2 g DM/d. Small intestinal DM digestibility ranged from 80.9% (LLM) to 74.0% (LLB) but was unaffected by treatment. Large intestinal DM digestibility did not differ among treatments (P = 0.652). Total-tract DM digestibility was higher (P = 0.020) for LLM (87.0%) than for SBM (84.8%). No difference in total-tract DM digestibility was observed for the two WSB foods (average = 83.3%; P = 0.286). Nitrogen retention did not differ among foods containing LLM and SBM (1.2 g of N/d; P = 0.486) or LLB and WSB (0.9 g of N/d; P = 0.225). Small intestinal N digestibility did not differ among LLM- and SBM-containing foods (80.6%; P = 0.190) or LLB and WSB (69.3%; P = 0.640). Total-tract N digestibility did not differ among foods containing LLM and SBM (83.5%; P = 0.627) or LLB and WSB (76.8%; P = 0.968). Tryptophan digestibility was higher for SBM than for LLM (P = 0.039). Histidine and tryptophan digestibilities were higher in WSB compared with LLB (P = 0.049 and P < 0.001, respectively). No differences in nonessential AA digestibility were observed when comparing soy-based foods. The results of this study demonstrate that LLM, SBM, LLB, and WSB can be effective sources of protein for canine foods and have a high digestibility. Differences in small intestinal digestibility of tryptophan and histidine may require consideration when formulating diets using low-oligosaccharide, low-phytate soybeans or meal.