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

Abstract

This retrospective study used 226 dogs and 296 cats to evaluate whether protein absorption was influenced by species, and within species, what influence increasing the percentage of total dietary protein, as plant protein, had on protein absorption. Each food was evaluated by at least one study with a minimum of six dogs or cats assigned to each study. Dietary inclusion of animal and plant based protein was calculated by analysis of ingredients and dietary inclusion level. Both dogs and cats were able to digest dietary plant protein, with protein digestibility in dogs unchanged as plant protein increased, while in cats, eating dry food, an increase in plant protein, was associated with increased protein digestibility. When individual plant high-concentration protein sources (excluding the protein from whole grains) were evaluated (i.e., soybean meal, soybean protein isolate, corn gluten meal, and rice protein concentrate) there was no response to increasing protein from these sources in the dog. In the cat, there was a significant positive effect on protein digestibility associated with an increasing concentration of corn gluten meal. In summary, as the dietary protein shifted from striated muscle and other animal proteins to plant based proteins, there was no effect in the dog, while in cats, increasing dietary plant protein was associated with increasing protein digestibility (5.5% increase at 50% protein from plants in dry cat food). Protein digestibility of food in dogs and cats is similar, if not enhanced, when the plant protein sources are concentrated from soybeans (soybean isolate, soybean meal), corn (corn gluten meal), or rice (rice protein concentrate).

Insect Larvae Meal (Hermetia illucens) as a Sustainable Protein Source of Canine Food and Its Impacts on Nutrient Digestibility and Fecal Quality

“…Another factor that could influence protein digestibility is dietary fiber content [55]. In the current study, although crude fiber content in the BSFL meal-based diet was two times more than the level in the PM-based diet (39.5 vs. 14.7 g/kg DM), this had no effect on protein digestibility.…”

“…Digestibility of crude protein decreased as total dietary fiber consumption increased in dogs [57]. The microbiome can both trap nitrogen as bacterial protein and liberate nitrogen as ammonia, therefore, fermentable carbohydrates may influence protein digestibility through lower tract metabolism [55]. Thus, in our study, certain effects on protein digestibility due to crude fiber content can be excluded or rather neglected because of the low contents and/or differences.…”

Varying Protein Levels Influence Metabolomics and the Gut Microbiome in Healthy Adult Dogs

“…Formulations and proximate analysis were carried out as previously described [10]. All foods were in dry form, and true and apparent digestibility assays were performed as previously described [46].…”

Nitrogen output in the urban environment using a vegetarian canine diet

“…However, there is no recommendation for the percent of protein, which should come from plants or animals [ 36 ]. Although protein adequacy requires the correct amino acids to be absorbed in their appropriate concentrations, the protein digestibility is a valuable indicator of protein nutrition [ 37 ]. In the current study, crude protein digestibility was similar for the meat-based diet and vegetarian diet.…”

“…From another point of view, wheat gluten is a highly digestible protein source with an apparent digestibility of 93.8% [ 41 ]. Similarly, inclusion of rice protein concentrate, corn gluten meal, soybean meal, and soybean protein isolate did not negatively influence protein digestibility compared to animal proteins in the canine diets [ 37 ]. Nevertheless, Bednar et al [ 33 ] found that the crude protein digestibility of the plant-based diet (containing soybean meal) was significantly lower (82.7%) compared to dogs fed poultry meal-based diet (87.5%).…”