Dairy cow personality: Consistency in a familiar testing environment.

Personality affects the behavior of dairy cows in response to various situations on farm, such as novel or social challenges, which can affect the welfare of individual cows. Personality traits are evaluated through behavioral testing, typically in unfamiliar environments, but this can be a time-consuming process. Using a novel object test (NOT) and a forced human approach test (FHAT), we tested 222 individual dairy cows and retested a subset of cows (n = 78) 8 mo afterward. The aim was to see if personality traits can be identified in a familiar environment and if traits were consistent in between test and retest. Principal component analysis was used to identify personality traits. Extracted components (personality traits) were named according to determining variables (loadings <-0.63 or >0.63). Based on identified personality traits we calculated the intraclass correlation (ICC) coefficient and the differences between personality trait in test and retest to assess consistency. We identified 3 personality traits from NOT measurements ("explorative," "boldness," and "sociable") explaining 85% of the variance and one trait from behavioral measurements in the FHAT ("trusting") explaining 74% of the variance. Mean ICC of 0.6 with a standard deviation of 0.18 shows that although traits are consistent at herd level, cows react individually in stressful situations. As both tests were carried out in a familiar environment and results are similar to other studies that used unfamiliar environments, we can conclude that tests can be performed in a familiar environment.