Measuring fearfulness of hens in commercial organic egg production
Abstract:To evaluate agreement between flock-based fear tests used in welfare assessments of laying hens in commercial organic farms, three tests were applied in 27 flocks of layers. Tests were performed at 35 and 55 weeks of age and were based on the concepts of 'novel object', 'sudden sound' and two different measures of 'approaching human'. In general, agreements between tests were poor. The two measures based on 'approaching human' had the highest agreement, while the agreement between all other flock-based tests were lower. There was low agreement between testing at age 35 and 55 weeks.
In order to evaluate the degree to which the flock-based fear tests reflect individual hens' underlying fearfulness; tonic immobility (TI) tests were also applied on individual hens in eight flocks. There was large individual variation in the duration of tonic immobility, but also significant difference between flocks regarding mean duration of immobilisation. However there was no statistically significant association between TI-tests and flock-based tests. These results emphasise the need for careful consideration of choice of test stimuli for flock-based fear tests, and indicate that the investigated flock-based fear tests do not reflect the individual hens' underlying fearfulness.