Cats and dogs showed a short-term preference for kibble containing some protein derived from microorganisms over kibble containing only standard, animal-derived protein, according to a new study.
Ally Motta de Matos and A.L.B. Cruz of MicroHarvest, a European company that produces protein ingredients through fermentation and targets pet food as its first market, published the findings in the open access journal PLOS One on Sept. 23.
According to the study, pets require a balanced intake of amino acids to stay healthy. Animal sources such as fish and poultry have traditionally been the primary protein sources in pet food, but concerns about the long-term availability and environmental impact of animal proteins are driving interest in alternatives, including proteins produced by fungi, yeast and bacteria in manufacturing processes.
According to the authors, prior studies have suggested pet foods containing microbial proteins can be nutritious and produced in environmentally sustainable ways. However, the viability of such products also depends on pets' willingness to eat them. To evaluate the palatability of kibble containing microbial proteins, Motta de Matos and Cruz tested it against standard animal-protein-only kibble.
The study
The researchers asked pet owners to offer their cats or dogs two bowls of food simultaneously for four consecutive meals over two days. One bowl contained standard animal-protein kibble, and the other contained a nearly identical kibble in which some of the animal protein had been replaced with microbial protein. The study involved 30 dogs and 30 cats, with all meals served in the animals' homes.
Statistical analysis showed both cats and dogs consumed a higher proportion of the kibble with microbial protein than of the standard kibble. Overall, dogs ate about 72% of the microbial-protein kibble compared with 50% of the standard kibble, and cats ate 51% of the microbial-protein kibble compared with 34% of the standard kibble. Both cats and dogs were also more likely to approach and eat the microbial-protein kibble first.
More research needed
The researchers noted the findings reflect short-term preference only and said more research is needed to explore the long-term palatability and health outcomes of microbial proteins in pet foods.
"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.
"Acceptance by the animal is an essential consideration when evaluating new ingredients for pet food," they added. "Demonstrating nutritional quality is important, but ultimately the food also needs to be something dogs and cats choose to eat."
Citation: Motta de Matos A, Cruz A (2026) Microbial Protein as a novel ingredient in pet food: A food preference study in dogs and cats. PLoS One 21(9): e0356767. https://doi.org/10.1371/journal.pone.0356767
Funding: This study was funded by MicroHarvest Unipessoal Lda. The funder provided support in the form of salaries for A.M.M. and A.L.B.C., funded the experimental work described in this study, and contributed to the study conception and preparation of the manuscript. The in-home palatability trial, including statistical analysis, was designed and conducted by the independent research organization Sense Test.
