Table 1

Percentage of commercial laying hens in different housing systems in Sweden in 2001–20041. The total number of hens varied between 5,042 to 5,904 million birds per year.
Year/Housing system
 2001
 2002
 2003
 2004
 2001–2004
Conventional battery cages
 66.5
 52.3
 26.0
 13.5
 38.6
Furnished cages
 7.5
 12.6
 24.2
 24.8
 17.6
Litter-based systems2
 22.6
 31.2
 43.8
 55.0
 38.7
Free range3
 3.4
 3.9
 6.0
 6.7
 5.1
Total
 100
 100
 100
 100
 100

1The table is based on data collected in May to August each year [5].

2Includes single-tiered floor systems and multi-tiered aviary systems.

3Flocks housed in litter-based systems indoors, with access to outdoor pens and pasture, including organic flocks.

Fossum et al. Acta Veterinaria Scandinavica 2009 51:3   doi:10.1186/1751-0147-51-3