Part 2: Behavioural and electroencephalographic assessment of upright restraint and head-only electrical stunning of broilers

Abstract

The majority of small- to medium-scale and Halal poultry processors still rely on electrical water-bath stunning, despite recognised concerns regarding its humaneness and effectiveness. The aim of this study was to evaluate a mechanical system that restrains and stuns broilers in an upright posture using head-only constant current electrical stunning. Two experiments were performed on slaughter-weight broilers. Experiment A (n = 37) assessed behavioural indices, carcase quality during restraint, and time to recovery following head-only electrical stunning at 400 (n = 15), 600 (n = 12) or 800 (n = 10) mA at 50 Hz (2.5-s exposure). Experiment B (n = 15) assessed electroencephalographic (EEG) and behavioural indices of brain function after constant current 600 mA head-only electrical stunning (50 Hz, 2.5-s exposure period) to determine the time to recovery of brain function. In Experiment A, all birds were rendered unconscious with all three current levels. However, time to return of neck tension, rhythmic breathing and balance was variable and longer for birds stunned at 400 mA, while 800 mA resulted in more wing flapping leading to carcase damage. In Experiment B, all birds recovered normal-like EEG activity. The mean time to return of rhythmic breathing was 37 (± 2) s; range: 24–50 s, with a trend towards a moderate correlation with return of normal-like EEG activity. In conclusion, this project demonstrated the proof of concept of upright restraint for head-only electrical stunning of broilers and the recoverability of the method, in line with Halal requirements.