With growing consumer demand for vegetarian and vegan pet diets, many formulations now rely on plant-based proteins such as peas and lentils. These ingredients provide high protein content but also contain anti-nutritional factors like phytate and insoluble dietary fiber, which can reduce nutrient digestibility. In this study, researchers tested whether enzyme supplementation—either before or after extrusion—could improve the apparent total tract digestibility (ATTD) of pulse-based vegan dog foods.
Two diet formulations were evaluated: a low-protein diet containing field pea and lentil flour, and a high-protein diet using pea and lentil protein concentrates. Each formulation was prepared in three variations: control (no enzymes), enzymes added before extrusion, and enzymes added after extrusion. The enzyme blends included cellulase, xylanase, protease, and phytase at different concentrations depending on protein level.
The trial involved ten mixed-breed adult dogs in a 6 × 6 replicated incomplete Latin square design, with fecal samples collected for analysis. Results showed that ATTD of organic matter, crude protein, crude fat, gross energy, and ash did not significantly improve with enzyme addition after extrusion. However, enzyme supplementation did influence fecal metabolites, increasing glucose, xylose, and certain short-chain fatty acids. Notably, adding enzymes after extrusion also increased stool moisture by 1.5%, resulting in looser stools.
Enzyme addition before extrusion reduced crude protein digestibility, likely due to heat damage during processing. The study also compared results to pigs fed the same diets and found higher digestibility in pigs, supporting their use as a translational model for canine digestion research. Overall, the findings suggest that while enzymes can alter gut fermentation and stool characteristics, they may not enhance nutrient absorption in vegan dog diets.
Source: Van Straten, W. P. G., Shoveller, A., Wang, L. F., Beltranena, E., Vasanthan, T., & Zijlstra, R., Journal of Animal Science, Published November 6, 2023.
