Attractiveness of scents varies with protein content of the diet in meadow voles

The diet consumed by animals can influence their physical condition and potential for reproductive success. Do differences in diet quality affect the attractiveness of secondary sexual characteristics to the opposite sex? This study addressed this question by examining the attractiveness of odours produced by meadow voles, Microtus pensylvanicus, that were fed diets that differed in protein content. Meadow voles that served as scent donors were maintained on one of three diets, consisting of 9, 15 or 25% protein, all of which are sufficient to maintain voles in reproductive condition. These diets influenced the attractiveness of all three odours tested (anogenital area, urine and faeces). Both male and female subjects preferred odours from donors on high-protein diets: subjects preferred odours of opposite-sex conspecifics fed a 15 or 25% protein diet over odours from donors fed a 9% protein diet. Females preferred two odours of males on a 25% protein diet over the same odours of males on a 15% protein diet. These results suggest a mechanism for mate choice via odour preferences based on the protein content of the food consumed by potential partners. Because animals compete for access to higher-quality diets in nature, the choice of a mate with a high-quality diet may also be a means of choosing a higher-'quality' individual. (C) 1997 The Association for the Study of Animal Behaviour.