MicroHarvest study finds microbial protein kibble wins pet preference test

Cats and dogs showed a preference for kibble containing microbial protein in a new peer-reviewed study from MicroHarvest, with both species consuming more of the experimental food than a comparable formulation based entirely on conventional animal proteins.

• The study involved 30 dogs and 30 cats, which were offered conventional kibble alongside a formulation containing microbial protein over four meals at home.
• Dogs consumed around 72% of the microbial-protein kibble offered, compared with 50% of the conventional formulation, while cats consumed 51% versus 34%.
• Microbial protein was included at 10% of the experimental formulation, replacing fish meal and part of the poultry meal used in the conventional kibble.

Published in PLOS One, the study examined whether microbial protein could meet one of the basic requirements facing any new pet food ingredient: whether animals actually want to eat it.

MicroHarvest, which produces protein ingredients through fermentation and has identified pet food as its first market, funded the research. Study authors Ally Motta de Matos and A.L.B. Cruz are both employed by the company.

The in-home palatability trial and statistical analysis were designed and conducted by independent research organization Sense Test, while Eurofins Food Testing Portugal performed independent analytical characterization of the experimental diets.

Researchers recruited 30 dogs and 30 cats and asked their owners to serve two bowls of dry extruded food simultaneously for four consecutive meals over two days. One contained a conventional animal-protein formulation, while the other was nearly identical but incorporated microbial protein at 10%.

The microbial ingredient replaced fish meal and part of the poultry meal in the formulation.

Across the trial, dogs consumed approximately 72% of the microbial-protein kibble offered, compared with 50% of the conventional food. Among cats, the corresponding figures were 51% and 34%.

Researchers also recorded which bowl the animals approached and ate from first. Both dogs and cats were more likely to select the microbial-protein formulation first.

“What we found particularly interesting was that both dogs and cats preferred the diet containing microbial protein in this short-term study, even though microbial protein replaced fish meal and part of the poultry meal in the formulation,” the authors said.

“These findings provide an encouraging starting point for understanding how microbial proteins may perform not only as a nutritional ingredient, but also from the animal’s perspective.”

Microbial proteins produced using fungi, yeasts or bacteria are being explored as alternative ingredients for pet food as manufacturers seek additional protein sources alongside established ingredients such as poultry and fish.

Previous research has examined their nutritional properties and production footprint, but palatability is another practical hurdle for commercial adoption. An ingredient may provide the required amino acids and nutritional profile, but that offers limited value if the finished food is rejected by the animal.

“Acceptance by the animal is an essential consideration when evaluating new ingredients for pet food,” the authors added. “Demonstrating nutritional quality is important, but ultimately the food also needs to be something dogs and cats choose to eat.”

The authors cautioned that the results demonstrate short-term preference rather than evidence of long-term acceptance or health effects. The trial covered only four meals across two days, and further research will be needed to assess longer-term palatability and health outcomes when microbial proteins are incorporated into pet food.

The study, Microbial Protein as a novel ingredient in pet food: A food preference study in dogs and cats, was published in PLOS One on September 23, 2026.

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