Material and methods
The experiment lasting for 40 weeks was conducted
with 232 Hisex Brown hens, 20 weeks
old. The laying hens were housed in conventional
cages Eurovent (72 hens, 3 hens per cage, 550 cm2
per hen), enriched cages SKN-O 30-60 (Kovobel,
Domažlice, Czech Republic) (60 hens, 10 hens
per cage, 750 cm2 per hen), aviaries (40 hens,
15 birds per m2
), and on litter (60 hens, 10 hens
per box, 7 birds per m2
). They were fed two feed
mixtures according to the age of hens (i.e. from 20
to 40 weeks of age and from 41 to 60 weeks of age).
The ingredients of the feed mixtures are listed in
Table 1. Feed and water were supplied ad libitum.
The daily photoperiod was set at 15 h light : 9 h