Influence of sequence length on the response to ahemeral lighting late in lay

1. An experiment is described in which 96 individually-caged SCWL hens in two rooms were used to investigate the response to changing to a 28-h cycle using a reverse treatment design. 2. The application of the 28-h cycle did not affect mean rate of lay but increased mean egg weight and egg output. 3. Grouping the birds according to their preliminary sequence length yielded an interesting outcome. In both rooms, birds with short sequences (< or = 6 eggs) produced significantly more eggs under the 28-h cycle, while those with long sequences (> 6 eggs) produced marginally fewer eggs. The same trend was also evident with egg output. 4. Changing from 24-h to 28-h increased yolk and albumen weights as well as shell quality. However, relative to egg weight, no measurable effect was detected due to light cycle, age or sequence length on yolk and albumen weights. 5. The paper provides new evidence suggesting that long ahemeral cycles could be used to improve egg production as well as shell thickness in flocks with modest rates of lay.