Exploring dairy heifers' consistency in social motivation in the absence or presence of conspecifics

We examined the consistency of heifers’ (n=36) sociability in the absence and presence of conspecifics. We applied standard animal personality tests to measure social motivation during social isolation. Additionally, we developed two novel test paradigms designed to quantify heifers’ willingness to trade off access to conspecifics in exchange for feed, thus measuring social motivation within a social context. In our distribution test, groups of three dairy heifers (n=12) could freely move between two feed troughs where grain was provided at two rates, with one providing twice as much feed as the other. Time feeding alone in the distribution test varied among heifers from 0 to 56.6 % of the time; this variation was weakly associated with differences in sociability as assessed by the time animals took to return to peers following social isolation, but not with heifers’ willingness to leave peers to access grain when tested in an alternative social-feed trade-off test. Our findings suggest that different measures of social motivation are not necessarily consistent, challenging the assumption that sociability is a stable personality trait in cattle. Instead, we propose to regard sociability as a ‘behavioural consequence’ resulting from the combined effects of internal characteristics (e.g., other personality traits such as fearfulness) and external factors (e.g., testing environment) at the time of evaluation.