Simple Summary
Because dogs are omnivores and cats are obligate carnivores, it is of value to pet owners and nutritionists to know how well they digest protein from plants and animals. This study evaluated the difference in digestibility using plant and animal protein sources, which are used in the pet food industry. These plant and animal sources resulted in protein digestibility that met or exceeded that expected for dogs and cats. As previously shown, cats had superior protein digestibility as compared to dogs. Regarding the difference in digestibility between the proteins from plants or animals—as a class, there was no difference between plant and animal protein in dogs. However, in cats, the protein from plants was more highly digested than animal protein.
Above from:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7143243/
Cats Have Increased Protein Digestibility as Compared to Dogs and Improve Their Ability to Absorb Protein as Dietary Protein Intake Shifts from Animal to Plant Sources