Behaviour and Well-being of Hens (Gallus Domesticus) in Alternative Housing Environments

SummaryWidespread concern is evident in some countries, especially those of Western Europe, for the well-being of hens in high-density environments. Evaluation of potentially stressful conditions is difficult and a multidisciplinary approach appears most suitable, except for cases of overt bodily injury or impaired health resulting in obvious morbidity or mortality. Changes in physiological and immune status appear most promising in identifying early stages of stress, but some physiological indicators return to baseline levels as known stressors continue to act. Individual-hen productivity, independent of economic considerations, has probably been neglected unfairly as an index of well-being, but appears to be especially promising as an indicator of chronic stress. Behavioural observations appear to be useful in providing insight into probable stressors and means of alleviating stressful situations, but are likely to be generally inadequate when standing alone.Behavioural problems associated with well-being in different housing environments tend to differ both qualitatively and quantitatively, but stress-free environments are unlikely to exist. Floor-pen housing is associated with social hierarchies and hens of very low status show signs of stress. Cannibalistic pecking poses a serious threat in floor pens as it does also in multiple-hen cages. Low social status appears to be a serious problem for hens in cages only when extreme crowding or extreme competition for feeding space is present. Escape behaviour and hysteria can become acute problems in cages, especially as group size increases. Genetic stock differences exist in fear-related and other behavioural activities which may contribute to stress. Certain individual-hen behavioural patterns, characteristic of wild or feral fowls, appear to be either nonadaptive or inappropriate in intensive husbandry systems.In very broad perspective, floor-pen, individual-hen cage, and low density or get-away multiple-hen cage housing appear to be roughly equivalent in terms of hen welfare. When group size and density increase beyond ill-defined levels in multiple-hen cages, adverse consequences become evident in terms of well-being of hens. Genetic strain differences in relative adaptability to high-density cage housing appears to be responsible for some inconsistencies observed between studies.Some pragmatic suggestions for improving hens' well-being in intensive husbandry systems include moderate beak trimming, claw trimming of caged hens in some genetic stocks, use of better quality materials and cage design to prevent injuries and hen entrapment, better identification of space and group-size requirements on a stock-by-stock basis for the cage environment, and further genetic adaptation.