A study on validity and reliability of on-farm tests to measure human-animal relationship in horses and donkeys

The development and maintenance of a positive human-horse/donkey relationship is essential in order to decrease accidents and reduce negative states of equine welfare. In many animal species the reaction of animals to humans during specific behavioural tests is influenced by their past interaction and is linked to the level of fear felt in the presence of a human. The present research aims to assess whether a set of on-farm behavioural tests allow differentiation between horse facilities with excellent or sub-optimal human-animal relationship. Furthermore, we evaluated mid-term repeatability (3-month intervals), inter-observer reliability and on-farm feasibility of these behavioural tests in single stabled horses and in group housed donkeys. Eleven horse and eight donkey facilities (N = 313 adult horses; N = 47 adult donkeys) were visited twice at 3-month intervals. Horse facilities were selected on the basis of reports of inspections on animal welfare conducted by competent local authorities; they were classified as "excellent" (N = 5) and "sub-optimal" (N = 6). Four observers, with no experience in assessing equine welfare and not aware of the a priori category of the facility, were trained to perform and score standardised human-equine behavioural tests: avoidance distance test (AD), voluntary animal approach test (VAA), forced human approach test (FHA), walking down side and tail tuck.All the behavioural tests carried out proved to be feasible in an on-farm environment. In spite of the fact that the reactions of horses were largely positive, those kept in facilities with "sub-optimal" relationship showed avoidance and aggressive behaviours more often when approached (GLMM P <. 0.05). As for donkeys, less than 30% of the animals exhibited negative behaviour towards the assessor.Observer's agreement of AD, VAA, FHA, WDS and tail tuck scoring was consistent for both species (percentage agreement ranged between 67.7% and 93.3%). Repeatability of tests was good for all the tests and no significant differences were found between two repetitions at 3-month intervals. Our results support the findings described for working donkeys and show that, also on-farm, the assessment of donkeys' reactions to an unknown human during standardised tests could prove useful in evaluating the quality of their relationship with humans.Further research is needed to verify if our findings can be generalised for different husbandry conditions.