A comparison of inversion test holding methods for broilers

Objective, robust, and repeatable assessments of fear responses of poultry can lead to improvements in research techniques, the validity of test results, and ultimately bird welfare. The objective of this study was to examine the effect of 2 different holding methods on broiler fear responses during the inversion test, a standardized method of assessing fear in poultry. On D15 and D34 mixed-sex broilers (N = 80) were inverted and held either by their shanks (N = 40) or feet (N = 40) at arm's length away from the experimenter for 30 s. The frequency of wing flapping, head movement, attempts to right, and vocalizations were observed from video recordings collected during the inversion test. Vocalizations at D15 and D34 were not different when comparing holding methods. Frequency of attempts to right and wing flapping at D15 were greater (P < 0.001) for birds held by their feet (0.90 and 16.6, respectively) than when they were held by their shanks (0.20 and 0.73, respectively). Similarly, on D34 wing flapping remained greater (P < 0.001) for birds held by their feet (23.8) compared to their shanks (8.1). Conversely, head movements were greater (P = 0.05) for birds held by their shanks (9.2) compared to their feet (6.3) on D15. Within both the shank and feet holding method, vocalizations at D15 were greater (30.7 and 35.6, respectively) compared to D34 (11.93 and 15.38, respectively) (P < 0.001). There was no holding method effect on head movements within each age. These results suggest that behaviors observed during the inversion test can be influenced by the inversion holding method and that handling should be standardized while conducting behavioral tests to assess fear in poultry.