The importance of pre-laying behaviour and nest boxes for laying hen welfare: a review

The housing of commercial laying hens in conventional cages is one of the most contentious animal welfare issues in animal production in Australia and other developed countries. The main issues are restriction of space and opportunity to perform 'natural' behaviours such as pre-laying behaviour, dust bathing and roosting. The provision of a nest box is argued by some to be essential for laying hen welfare. While the majority of hens (at least 70%) will lay in a nest box if provided, neither the lack of a nest box nor the sudden denial of access to a nest box, result in adverse welfare based on physiological stress response measured via corticosterone concentrations in either plasma or egg albumen. However, recent research suggests that hens that spent more time sitting during the 2 h before egg laying had lower plasma corticosterone concentrations, when sampled similar to 4-5h post-egg laying. On the other hand, hens that displayed more bouts of sitting before egg laying, perhaps suggesting they were more frequently disturbed and thus less settled, had higher corticosterone concentrations. One function of nest boxes might be to provide those hens that choose to lay there with a location where they are less disturbed before egg laying. Further research on the effects of pre-laying behaviour and nest site selection on physiological stress in laying hens may provide important information regarding how to house commercial laying hens for good welfare.