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Feeding Soy Protein to Companion Animals

August 2017

Animal proteins, such as poultry by-product meal (PBM), are commonly used in extruded dog foods. Plant-based proteins have a more consistent nutrient profile than animal sources but may contain anti-nutritional factors (ANF), including trypsin inhibitors and oligosaccharides. The test protein, HP 300, is a proprietarily processed soy-based product (Hamlet Protein Inc., Findlay, OH.) with very low ANF concentrations and high nutritional value.

The objective of this experiment was to evaluate if HP 300 can be an effective PBM replacement in pet food and if there are practical limits to its use. The experiment was to compare graded levels (0% (control), 4%, 8%, 12%, 24%, and 48%) of HP 300 on apparent total-tract macronutrient digestibility, fecal characteristics, and fecal fermentative end products in healthy adult dogs. All six diets were formulated to meet AAFCO nutrient profiles with approximately 30% crude protein and 16% fat. Forty-eight healthy adult beagle dogs (20 females, 28 males; mean age: 3.4 y; mean BW of 10 kg) were studied in a completely randomized design. The treatment period consisted of a 10-day diet adaptation phase followed by a 4-day fresh and total fecal collection phase.

Results indicated that stool output (both on as-is and dry matter basis did not differ from control until 48% HP 300 (P < 0.01). Fecal output per unit food intake on a dry matter basis differed (P < 0.01) from control only for the 24% and 48% HP 300 inclusion rates. Notably, no effect of HP 300 inclusion was found for stool consistency scores. Digestibility of dry matter, organic matter and energy did not differ from control at any inclusion rate, except for a decrease (P < 0.01) at 48% HP 300, which is likely due to increased dietary fiber concentrations. Crude protein digestibility was not affected by treatment and ranged from 82.9 – 86.2%. Overall, these data suggest that HP 300 is a suitable replacement for PBM in canine diets up to at least a 24% inclusion rate.