Reviewing the scientific literature, researchers based in Australia suggest that nest boxes offer an area where hens are not disturbed before laying, for the majority of birds that choose to use nest boxes. Work they reviewed did not provide evidence that a nest box is essential for hen welfare, however.
In a review published recently in Animal Production Science, Greg Cronin of the University of Sydney and co–authors from the University of Melbourne state that 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, they say, 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 per cent – 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 two hours before egg laying had lower plasma corticosterone concentrations, when sampled around four to five hours 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.
Cronin and co-authors conclude that 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.
Cronin G.M., the late J.L. Barnett and P.H. Hemsworth. 2012. The importance of pre-laying behaviour and nest boxes for laying hen welfare: a review. Animal Production Science 52(7):398-405. doi:10.1071/AN11258