A pecking device as an environmental enrichment for caged laying hens

摘要

To improve the welfare of caged laying hens, a pecking device made of stones was introduced on the cage floor. Twenty-four White Leghorn hens aged 15months were divided into four groups: single-housed hens with device, single-housed control hens, pair-housed hens with device and pair-housed control hens. Hens housed with the device pecked at various pecking objects less often than control hens. Agonistic behavior was also lower in hens with the device than in hens without the device, implied a possibility of improvement in quality of pecking stimuli with the device. Not only time spent pecking, but also quality of pecking might be important to fill their need for stimulation. Both single- and pair-housed hens more often pecked at the device in the evening. Response to various pecking objects also showed that pecking behaviors were most frequently expressed in the evening. Increased foraging at dusk is a well-known habit; therefore, the increase in pecking behavior in the evening might reflect the hens' general circadian rhythm. These results indicate that the device made of stones could promote some instinctive behavior. Enhancement of behavioral repertories and reduced agonistic behavior with the pecking device might improve the welfare of caged laying hens.