Meeting consumer demand for more plant-based pet foods

What the research says

Plant proteins have been well studied in recent research, which shows these ingredients may even come with some benefits for carnivorous companions – as long as diets are formulated and processed carefully.

Studies of plant-based proteins in pet diets over the past two years have pointed to generally favourable results. Diets containing high concentrations of legume and yeast-based proteins performed well in dogs, according to a study published this June in the journal Frontiers in Veterinary Science. The study found that high-plant diets may support gut health in addition to providing readily digestible proteins. In another study, increased inclusion of concentrated plant-based proteins in the diet of cats – which are obligate carnivores – actually improved their ability to digest proteins.

Pick your protein

But as with anything, plant-based pet diets do come with some caveats, as some ingredients are not as readily digested as others. According to Maria Regina Cattai de Godoy, an associate professor in the companion animal comparative nutrition lab at the University of Illinois at Urbana-Champaign, a series of studies from her laboratory showed that while pets might struggle to absorb amino acids from dark-roast peanut flour and soy flakes, a variety of plant proteins were equal or even superior to animal-based proteins with respect to the availability of amino acids, including options such as corn gluten meal, yellow peas and green lentils, and a variety of beans.

Nutrients, not ingredients

However, it is not the ingredient itself that should be singled out for praise or blame, Cattai de Godoy says.

“It is very important to understand that an ingredient will rarely provide a single source of nutrients and, in the process of creating complete and balanced diets for pets, we need to use combinations of ingredients of complementary nutrient profiles to achieve that,” she says. “Animals (like humans) do not have a requirement for ingredients, but rather for nutrients.”

Pitfalls

Two primary pitfalls can make plant-based proteins more difficult to digest when included in pet diets, according to Gary Davenport, companion animal technical manager at ADM: the total fibre content and the presence of antinutritional factors.

Fibre is not broken down in the digestive process and absorbs water, potentially trapping nutrients. Antinutritional factors are somewhat situation- specific – for example, soybeans contain a trypsin inhibitor, which prevents a key digestive enzyme from working properly.

Handle with care

Fortunately, there are a number of viable workarounds, Davenport says. Simply choosing an alternative plant protein that is more easily digestible, such as peas, is one option – though he notes each ingredient comes with pros and cons. Peas are lacking in methionine, which is essential to healthy metabolism, so a pea- based diet would require some supplementary source of this amino acid.

Alternatively, the addition of enzymes to the diet may help break down fibre and antinutritional properties. However, Davenport notes this may only be effective in raw diets since the application of heat disrupts the activity of most enzymes and studies have been hard-pressed to find evidence of enzymatic activity in finished diets.

“Sometimes you will see foods that are marketed with enzymes,” Davenport says. “But if that is a product that has been heated in some way, I would be sceptical if there is that much enzymatic activity.” Heat itself might be the most straightforward way to render plant proteins more digestible to cats and dogs, he explains. Heat and steam can inactivate a variety of antinutritional compounds, including trypsin inhibitors, and help to break down fibre.

Over-processing of some ingredients, as with the dark-roast peanut flour, may decrease the digestibility of proteins contained in those ingredients, Cattai de Godoy cautions, so it is important to treat each situation on a case-by-case basis. But on the whole, says Davenport, there is no need to worry about introducing a few more vegetables into pets’ diets.