RESTRICTED VISUAL INPUT REDUCES STRUGGLING IN SHACKLED BROILER-CHICKENS

Violent struggling and wing flapping during shackling and inversion ca n seriously injure chickens and other poultry. Apart from harming the birds' well-being by eliciting chronic pain states and their associate d deleterious effects, such injuries could also reduce productivity an d product quality. Not only are birds shackled during pre-slaughter pr ocessing but growing broilers and laying hens are often suspended by t he legs for examination by the farmer or a veterinarian. The present s tudy tested the hypothesis that restriction of visual input by hooding immediately before shackling would promote the adoption of immobility in broiler chickens, The hood consisted of an unbleached cotton wash mitten which was secured round the bird's neck with a drawstring. Hood ed broilers and their non-hooded controls were shackled in daylight (a pproximately 625 and 55 lux, respectively, inside and outside the hood ) at the entrance to the poultry house when they were 29 days old in e xperiment 1 and at 45 days of age in experiment 2. By contrast, in exp eriment 3, birds were tested in a darkened room (2 and 0 lux, respecti vely, inside and outside the hood) at 42 days of age. All birds were t ested individually and once only. The results of all three experiments clearly supported our hypothesis. Covering the broilers' heads with a hood before they were shackled substantially reduced the time spent s truggling as well as the numbers of struggling bouts and vocalizations . Therefore, regardless of their age or of the ambient light intensity , we recommend that broiler chickens should be hooded before they are suspended from shackles for weighing or for veterinary examination. (C ) 1997 Elsevier Science B.V.