Validation of tests for on-farm assessment of the hen–human relationship in non-cage systems

The relationship of laying hens towards humans is an important aspect of animal welfare. Tests for assessing the hen–human relationship on farm should be validated prior to their use. In this paper, we investigated the validity of three recently developed tests assumed to measure the hen–human relationship in non-caged hens. The study was conducted in two identical houses on a commercial free-range farm on 12 groups of laying hens, each group comprising about 500 birds brown hybrids. Over a 2-week treatment period, six groups of laying hens received 15 min of additional human contact twice daily (additional contact groups), consisting of walking, talking, feeding and touching single birds. Six control groups received only minimal human contact besides the routine management. Immediately before and after the treatment period, all groups were tested with the three tests. These were measuring the reactions of hens towards a stationary person (stationary person test, SPT), a moving person approaching individual hens (avoidance distance test; ADT) and a stationary person trying to touch individual hens (touch test; TT). Additionally, a test to assess fear of novelty (novel object test; NOT) was performed. Exposure to additional human contact led to significant differences between additional contact and control groups in all parameters of the three tests assessing the hen's relationship to humans (all; p < 0.01). The avoidance distance decreased (ADT; p = 0.028), whereas the proportion of touched birds (TT; p = 0.028) and the number of birds near the test person (SPT; p = 0.028) increased after the 2-week handling period within the additional contact groups but not in the control groups. These findings suggest that (1) the tests effectively measure the human–hen relationship and support the validity of the tests and (2) reactions of laying hens to humans can be actively influenced by the quality of human contact in non-cage systems.