To sum up, group size has some impact on zootechnical performances
and affects some hen behaviours, but there is no data
available about impact of group size on PS and DB in furnished
cages. Moreover, the requirement to have PSA in cages raises several
problems, as the litters preferred by hens for DB are not suitable
in cages. Feed is commonly used in commercial conditions although
it is not an ideal litter, but as far as we know its impact on PS and DB
behaviours has never been studied in furnished cages. Wheat bran could be an interesting alternative to feed as litter, but has not been tested in furnished cages to assess PS and DB behaviours. Rubber
mats could be an alternative to artificial turf mats commonly used
as PSA materials to reduce hygiene problems, but this has never
been assessed regarding hens’ DB and PS behaviours.