A dog's body can only use what it actually absorbs. That's the part kibble bags never put on the front label, and it's the part a study out of a 2024 feeding trial finally put numbers on.

Researchers ran ten adult beagles through a rotating five-diet trial: extruded kibble, fresh food, frozen raw, freeze-dried raw, and a fifth blend, each fed for a full 35-day cycle. They measured exactly how much protein, fat, and energy came out the other end versus how much stayed in the dog. Extruded kibble finished last on every measure. Protein digestibility landed at 81.99% for kibble, compared to 94.17% for freeze-dried raw and 93.00% for frozen raw. Energy told the same story: 83.76% for kibble against 93.21% for freeze-dried raw.

Those aren't small gaps. A dog eating freeze-dried raw is absorbing roughly 12 percentage points more of the protein in its bowl than a dog eating kibble, meal after meal, year after year.

A separate study published in 2021 in the same journal ran a comparable comparison between fresh food and extruded kibble and landed on the same conclusion: fresh diets outdigested the extruded product. Two independent trials, two different research teams, same direction.

Kibble is cooked under high heat and pressure to hold its shape, and that process changes the protein itself. Heat-damaged protein binds together in ways a dog's digestive enzymes can't fully break apart, so some of it passes straight through undigested. Extrusion also loads the formula with starch, usually 30% to 60% of the recipe, just to get the dough to hold together and puff correctly in the machine. None of that starch exists to feed the dog. It exists to feed the manufacturing process.

Raw and freeze-dried raw formats skip that step entirely. The protein structure stays closer to what a dog's digestive system evolved to break down, and there's little to no starch filler diluting the nutrient density of each bite.

Ten beagles is a real trial, not a guess, but it's still a small, short sample, and the researchers didn't publish who funded it. Higher digestibility means less food passes through unused. It doesn't automatically mean a longer life or fewer vet visits — that leap isn't what either study claims. What it does mean is measurable: more of what's in the bowl is actually reaching the dog.

That's the number kibble marketing skips. The bag talks about ingredients. It never talks about what's left of them by the time they reach the small intestine — and on that measure, freeze-dried raw isn't just ahead. It isn't close.