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Study: Human-grade dog food diets may lead to less pooping

New research from the University of Illinois (UI) indicates that commercially available dog food made with human-grade ingredients results in less fecal output than kibble-based dog food.

According to the Association of American Feed Control Officials (AAFCO), for dog food to be labeled human grade (HG), every ingredient and the finished food must be stored, handled, processed, and transported according to the current good-manufacturing practices for human-edible foods.

In the study, the researchers fed 12 healthy, adult beagles four commercially available diets over four 28-day periods. The diets included a standard extruded diet (kibble); a fresh, refrigerated diet, which included chicken, ground oats, chicken liver, rice bran, eggs, and carrots; and two fresh diets made using only US Department of Agriculture–certified HG ingredients, which included minimally processed ingredients such as beef, chicken, rice, carrots, and broccoli.

The researchers write that “dogs fed HG foods had 2 to 3 times lower fecal output than dogs fed the extruded diet and about 1.5 times lower fecal output than dogs fed the fresh diet.”

NEWStat reached out to lead researcher Kelly S. Swanson, PhD, MS, professor of animal and nutritional sciences and veterinary clinical medicine at UI, to find out more.

First, a caveat.

Swanson told NEWStat that the study has gotten a lot of press and has caused some confusion, so he wanted to use this opportunity to clarify a couple of points: all of the diets tested were complete and balanced commercial diets—not homemade. Additionally, all were cooked, not raw.

He said that many people are taking the findings to mean that any human food can be fed to dogs. “That is not true: the results of our study pertain to commercial diets only. If a pet owner wants to feed a homemade diet, they should work with a board-certified veterinarian to make sure that it’s complete and balanced and appropriate for the pet in question.”

So what were the major differences in outcome between the dogs who ate the extruded, fresh, or HG diets?

Swanson said that his team analyzed stool characteristics, nutrient digestibility, stool volume, and blood chemistry. “There were no real changes to serum chemistry or stool characteristics. This was expected because all foods were complete and balanced diets.” The HG foods had the highest digestibility and the lowest stool volume while the kibble had the lowest digestibility and highest stool volume. “The fresh diet also performed quite well, with digestibility being slightly lower and stool volume being higher than the HG foods.”

Swanson said the nutrient digestibility and stool volume data were the most significant: “To our knowledge, this is the first published, peer-reviewed paper reporting the effects of human-grade dog foods and one of only a few reporting the effects of fresh dog foods.”

He noted that the findings seemed to confirm a previous study that demonstrated fresh pet diets were more digestible and led to lower stool volume than a kibble diet. Swanson stressed that the researchers were unable to attribute their results to any one factor, because the ingredient sources, nutrient content, and processing methods differed among all the diets: “Each of these factors, and possibly others, are important,” he said. That means diets within each segment—kibble, fresh, and HG—will likely vary depending on what they’re composed of and how they’re produced.

He added, “However, I would expect these general differences among diet segments to stand in most cases.”

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