Effectiveness of electrical stunning applied using a variety of waveform-frequency combinations and consequences for carcase quality in broiler chickens.

1. The effectiveness of electrical stunning of poultry was assessed where the recommended current of 105 mA per bird was applied using a range of waveform-frequency combinations. In addition the effect of the treatments on subsequent carcase quality was investigated. 2. The use of frequencies greater than 50 Hz was associated with a failure to induce ventricular fibrillation. 3. All waveform-frequency combinations were equally effective in producing a stunned state; the time to recovery was not affected by stunning treatment but was significantly longer in heavier birds. 4. The use of high frequency (500 Hz and 1500 Hz) stunning currents resulted in a decrease in carcase downgrading and a marked reduction in the occurrence of breast muscle haemorrhages, which represent significant commercial benefits to be gained by their use.