Microbial Protein as a novel ingredient in pet food: A food preference study in dogs and cats.

The increasing demand for protein sources in pet nutrition has driven growing interest in microbial proteins (MP) as viable alternatives to traditional animal proteins. However, their successful incorporation into pet food formulations depends not only on nutritional adequacy but also on short-term food preference. This study evaluated the palatability of dry extruded diets containing 10% microbial protein in dogs and cats using an in-home two-bowl preference test and complemented these findings with independent laboratory characterization to support interpretation of the observed preferences. Palatability was assessed in 30 dogs and 30 cats over four meals by comparing MP-containing diets with macronutrient matching control diets differing only in protein source. Trials were conducted in-home to ensure natural feeding behavior, and data on food consumption, first approach, and primary consumption were collected. In both species, animals showed a statistically significant preference for diets containing microbial protein. Dogs consumed 72% of the MP-containing diet compared to 50% of the control (Wilcoxon signed-rank test, p = 0.002), whereas cats exhibited a consumed 51% of the MP-containing diet compared with 34% of the control diet (p = 0.001). Behavioral observations indicated that both dogs and cats more frequently approached and consumed the MP-containing diets first, a preference for the MP-containing diets. To contextualize these palatability outcomes, control and MP-containing diets were analyzed by an independent laboratory for proximate composition, amino acid and fatty acid profiles, selected minerals, and targeted volatile compounds. The analysis confirmed comparable macronutrient composition between diets, with MP-containing diets showing a complete amino acid profile, higher tryptophan content, and a lower omega-6: omega-3 ratio. Targeted volatile screening did not reveal analytical indicators typically associated with off-flavors in either of the diets. Together, these findings indicate that the preference observed in dogs and cats for MP-containing diets occurred within a nutritionally comparable formulation framework and may be supported by favorable analytical characteristics relevant to short-term food preference. This exploratory study provides complementary evidence supporting the feasibility of microbial protein inclusion in extruded pet food formulations and lays the groundwork for future research focused on long-term feeding outcomes, health and optimization of palatability. The present findings are limited to short-term food preference under the conditions evaluated and should not be interpreted as evidence of long-term acceptance or health effects.