Four hundred and thirty-two 85-week old layer hens of a brown egg layer strain (Brown Nick), at the initiation of the second egg production period, were housed in cages located in a three-deck battery-type cage block. Birds were randomly assigned to four dietary treatments. Each treatment consisted of six replications of three cages and the hens of three adjacent cages were considered to be an experimental replicate (18 hens per replicate and 108 hens per treatment). The dimensions of each cage were, 60 cm long, 50 cm wide and 56 cm high, and six hens were placed in each cage. Hens were housed in an open-sided, naturally ventilated experimental hen house and the room temperature ranged from 19 to 30 °C throughout the laying cycle. The experiment was carried out over a 21 week period, with the hens being between 85 and 105 weeks old, soon after the forced-moulting procedure. The Ministry of Agriculture, General Directorate of Research Institutional Animal Care and Use Committee approved the techniques and procedures involved in the animal care and handling (Protocol No: 2007-493).