| heal.abstract |
A modified-atmosphere killing system mounted on a trailer was tested for the purpose of humanely depopulating backyard or other small poultry flocks in emergency situations. It was evaluated using CO 2 and N 2 to kill spent layer breeders, spent laying hens, turkey broiler hens, and broiler chickens of several ages. The system performed well with either gas when the atmosphere in the killing chamber was controlled automatically by sensors, or when it was manually guided by the operator's observation of bird behavior. With CO 2, birds could be loaded continuously into a killing atmosphere because it was possible to maintain sufficiently high concentrations of the gas during the process. As a result, the conscious experience of each bird in the chamber was short. Automated control of the gas delivery system was helpful to hold CO 2 at a preset level, ensuring a quick kill of birds while minimizing CO 2 consumption. It also eliminated the need for an operator skilled at interpreting bird behavior to judge the quality of the atmosphere in the chamber. With N 2, birds must be killed in batches because the very low levels of residual O 2 necessary to cause death cannot be maintained during loading. As such, automation of gas delivery is unnecessary when using N 2 and the gas valve can be opened manually after a batch of birds is loaded to allow continuous gas injection until the birds expire. The chamber was able to hold more than 1,200 lb (544 kg) of carcasses, which numbered from 79 turkeys weighing 15.6 lb (7.1 kg) to almost 600 broiler chickens weighing 3 lb (1.4 kg) in the tests of this study. This capacity is more than enough to hold most backyard flocks in 1 load, and the fully loaded trailer can be towed without difficulty by a half-ton pickup truck. © 2012 Poultry Science Association, Inc. |
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