Data reported by Van den Brand et al. (2004)
documented that egg weight increased with the
age of hens. This was not confirmed by our study,
because the highest egg weight was at 59 weeks of
age in hens that were housed in conventional cages.
The egg weight of the laying hens that were housed
in the outdoor system decreased until they were
59 weeks of age, and then the egg weight increased
(Table 2). In enriched cages and litter system, the
egg weight increased (with few exceptions). These
results agree with the results of many authors,
e.g. Jiang and Sim (1991), O’Sullivan et al. (1991),
Peebles et al.