Science and its application in assessing the welfare of laying hens in the egg industry

To provide a rational framework for the scientific assessment of welfare and to use this framework to assess the welfare implications of issues relevant to the Australian egg industry.

A well-accepted approach to the assessment of animal welfare, based on assessing how well the animal is adapting, is described. This approach is used to consider the welfare implications of issues such as space, perches, nest boxes, dust baths, abrasive strips and non-cage housing systems.

The role of science in the welfare debate is to provide biological facts and thus it is important to separate welfare and ethics. The welfare of an animal in response to a housing system or husbandry procedure can be assessed by evaluating how much has to be done by the animal in order to cope and the extent to which the coping attempts are succeeding. Using this approach there is evidence for improved welfare from increasing space in cages, based on reduced aggression, corticosterone concentrations and mortalities and increased production, and for incorporating perches, based on the reduction in injuries at depopulation. Similar evidence for the inclusion of dust baths and nest boxes is lacking. The data on abrasive strips are equivocal with recommendations from overseas for their inclusion, whereas some local data have shown an increase in mortality can occur. Similarly, the data on non-cage systems are equivocal. The data on bone strength suggest improved fitness in non-cage systems, the data on stress suggest fitness may be better, similar or worse in non-cage systems, and the limited data on immunology suggest fitness may be worse in non-cage systems than in conventional cages.