Study finds cats, dogs prefer kibble with microbial protein

A new study suggests microbial protein may clear one of the toughest hurdles in alternative pet food ingredients: getting cats and dogs to actually want to eat it. In a PLOS One paper published September 23, 2026, researchers reported that both species preferred kibble containing microbial protein over a conventional animal-protein control in short-term, in-home feeding tests. Dogs consumed 72% of the microbial-protein kibble versus 50% of the control, while cats also showed a statistically significant preference for the microbial-protein formula. (eurekalert.org)

The work lands as the pet food sector is under growing pressure to find protein sources that are less exposed to livestock supply constraints, price volatility, and sustainability scrutiny. Microbial proteins, produced through fermentation, have drawn interest because they can be manufactured without raising animals and may offer a consistent amino acid profile. Industry attention has been building: MicroHarvest, the company affiliated with the study authors, has already launched microbial-protein pet treats in Europe and says pet food is its first commercial market, while also advancing plans for larger-scale production in Germany. (aaha.org)

According to the preprint and the published coverage, the researchers tested nutritionally equivalent extruded diets in 30 dogs and 30 cats using a two-bowl preference design conducted in the animals’ home environments. The test diet included 10% microbial protein and replaced fish meal plus part of the poultry meal in the control formula. The authors said both species approached and consumed the microbial-protein food first more often, pointing to sensory appeal rather than simple novelty alone. They also flagged important limits: small sample size, short duration, and the fact that the study was designed to assess preference, not long-term health, digestibility, or nutrient utilization. (assets-eu.researchsquare.com)

That caution matters because palatability is only one piece of the veterinary nutrition puzzle. Prior work on fermentation-derived ingredients in companion animals has been promising but still limited. A 2024 Frontiers pilot study in dogs found greenhouse gas-derived fermented protein was well accepted and well tolerated over a short feeding period, with no major digestive problems reported. Earlier open-access research on dried yeast in extruded dog and cat foods also found acceptable or improved palatability in dogs, while calling for more work on digestibility and dose-response effects. Taken together, the evidence suggests fermented proteins can be usable in pet food, but the database remains early and ingredient-specific. (frontiersin.org)

Outside the paper itself, expert and industry commentary has centered on the same issue: alternative proteins will need to prove not just environmental value, but nutritional performance and acceptance. AAHA’s recent overview of precision-fermentation proteins in pet food noted that the category is being framed as a response to the nontrivial environmental footprint of pet food production, while commercial players are positioning these ingredients as scalable substitutes for some conventional animal proteins. That broader framing helps explain why palatability data, even from a small study, gets attention. If pets reject the food, the sustainability case is irrelevant in practice. (aaha.org)

Why it matters: For veterinarians and nutrition-focused teams, this study is a signal, not a verdict. It suggests microbial protein could become a practical ingredient option in maintenance diets, limited-ingredient products, or formulations aimed at pet parents seeking lower-impact foods. But it doesn’t yet establish adequacy for long-term feeding, performance in animals with gastrointestinal disease or food sensitivities, or how these ingredients compare on digestibility, stool quality, amino acid bioavailability, and cost at scale. The authors disclosed no competing interests in the preprint, but both are affiliated with MicroHarvest, so independent replication will be important before the findings meaningfully shift clinical recommendations. (assets-eu.researchsquare.com)

There’s also a market access question. In the U.S., ingredient adoption in pet food depends not only on formulation success, but also on regulatory pathways and ingredient definitions. Recent AAFCO agenda materials show the ongoing pace of ingredient-review work for novel protein sources, underscoring that commercial momentum and regulatory acceptance do not always move at the same speed. For veterinary professionals advising pet parents, that means availability, labeling, and claims may vary by market before the science fully matures. (aafco.org)

What to watch: The next meaningful milestones will be peer-reviewed long-term feeding trials in both dogs and cats, independent digestibility and tolerance data, and evidence on where microbial proteins fit commercially, whether in treats, mainstream maintenance diets, or more specialized veterinary nutrition products. (assets-eu.researchsquare.com)