The Science of Pet-Food Digestibility

Key points:

• Digestibility refers to how much of a food’s nutrition a dog absorbs.
• Research has clinically proven that The Farmer’s Dog is highly digestible.
• The process used to make typical kibble results in highly variable—and lower—protein digestibility.

There are many important factors to consider when you’re evaluating the quality of a pet food. Is the food formulated by on-staff, board-certified nutritionists to be 100% complete and balanced according to AAFCO standards? Does the manufacturer meet or exceed WSAVA’s guidelines for selecting a pet food?

One key indicator of a food’s quality is digestibility. If a food is highly digestible, it means that your dog is actually getting the nourishment the food is designed (or advertised) to provide. That seems like a basic test for a daily diet to pass, but many commercial, dry diets promising “premium” ingredients and “meat as the first ingredient” are less digestible than fresh foods.

Here’s what to know about this key metric, what constitutes good vs. poor digestibility—and research showing that fresh, high-quality proteins like those in lightly cooked food from The Farmer’s Dog are more digestible than those in heavily processed dry food. 

What is digestibility?

Digestibility is a term for how much of a food’s nutritional value can be absorbed into an animal’s bloodstream and used by their body.

“Bioavailable” is a closely related term referring to nutrients that enter the bloodstream and can be used by the body’s tissues.

How is digestibility measured?

When it comes to digestibility, the proof is in the poop. Digestibility is typically measured through feeding tests—after a transition period, dogs are fed a set amount of a specific diet, and their fecal matter is collected and analyzed. The digestibility percentage (or coefficient) is determined by measuring the total daily amount of food consumed minus the amount that’s in the poop. This results in a total tract digestibility percentage. The values can also be broken down into protein, fat, and energy (or caloric) digestibility. 

In a way, you can run your own miniature digestibility test when you switch your dog to The Farmer’s Dog from kibble. When you notice smaller poops, that may be a sign that your dog’s food is more digestible than what they’d previously been eating. 

What is good vs. poor pet-food digestibility?

So how digestible are some of the most common pet foods? And how does digestibility vary by food type? 

A good guideline is as follows:

Less than 75% is poorly digestible/poor quality, 75 to 82% is moderately digestible/moderate quality, over 82% is highly digestible/high quality, and above 88% is exceptionally digestible/exceptional quality.
Depending on the ingredients used and extrusion process, kibble protein digestibility can range from 64 to 91%.

The Farmer’s Dog food and digestibility

The Farmer’s Dog has conducted studies to prove digestibility and macronutrient bioavailability. We make this information available to prospective and current customers, because we know digestibility is a real dietary difference-maker. It’s not enough for a dog to consume sufficient nutrients; those nutrients have to be absorbed by the body in a usable form instead of just passing through. The science reinforces that The Farmer’s Dog recipes are providing complete and balanced nutrition in a form that is genuinely fueling dogs’ long-term health. 

Digestibility: Why pet-food ingredients and processing matter

The true quality of a pet food can be difficult to determine based solely on the ingredients and other words and pictures on the label. Complete and balanced foods with similar ingredients and guaranteed analyses can vary significantly in digestibility. Ingredient quality and processing can make a big difference. The process typically used to make kibble robs the food of nutritional value. 

To make dry kibble, the ingredients go through multiple rounds of high-heat processing including a process called extrusion. When the kibble “dough” goes through this process, a chemical transformation called the Maillard reaction occurs. This makes the amino acids in the food less bioavailable—so the body can’t use them for metabolism, skin and coat, immune function, and other needs. The reaction also results in lower protein digestibility—and, sometimes, more and smellier poop. Proteins not absorbed by the GI tract end up in the colon, where they may also change the bacterial flora. Ultimately, they come out as poop.

Studies have proven that the process used to make kibble reduces its bioavailability. As one study concluded, the undesirable effects of extrusion include reduction of protein quality, decrease in palatability, and loss of heat-sensitive vitamins.

In contrast, our fresh, lightly cooked food is clinically proven to be highly digestible and clinically shown to be highly palatable. Our recipes start with human-grade meat and produce, and every step of our sourcing, cooking, packaging, and storage processes meets the same standards required for human food.

Why high-quality poop is important

One hallmark of a highly digestible diet is what we call “high-quality poop.” A digestible diet will affect the quality and quantity of your dog’s poop—it’ll be less voluminous than their poop on a kibble diet.