Dairy cow personality: Associations with home pen behavior and performance

Personality traits cause inter-individual variation in behavior and therefore represent an important factor of dairy cow health and wellbeing. As personality traits are usually assessed by conducting behavioral tests in an experimental arena, the question remains, how personality traits may differ in home pen behavior. Furthermore, it remains unclear, to what extent personality traits, home pen behavior and performance of dairy cows are associated. In this context, we recorded the milk yield, milk contents and feeding behavior of 271 cows for 14 days prior to conducting a novel object test, followed by a forced human approach test. For the same period the lying and walking behavior of a subset (36 cows) was additionally tracked via a real time location system. Using linear models, we estimated the association of traits inferred from test measurements with home pen behavior and production characteristics. These models included the cows exploration, boldness, sociability and trust in humans score as well as pairwise interactions between them. Two parameters describing home pen behavior were affected by interactions of personality traits. Within the group of less bold cows, the level of exploration was positively associated with the number of lying bouts per day. Furthermore, within the group of less explorative cows, the less bold cows had a higher variance in their walking bout duration than bold cows. Among production characteristics, feed intake was affected by different levels of exploration, sociability and trust. The effects depended on the expression of interacting traits such as boldness, sociability and trust. Most of these interactions also influenced milk yield and milk contents. This influence may be attributed to changes in the feeding behavior, which, in turn, is influenced by personality. However, milk yield and milk constitution were also influenced by boldness, when cows were additionally characterized as less sociable. Thereby the results indicates that personality and production may be related by other mechanisms. Regarding these findings, we suggest further research focusing on particular associations to determine causal relationships.