Review of life-history lighting programs for commercial laying fowls

SummaryThis review discusses lighting programs used during the growing period and laying cycle to aid in the selection and/or design of life-history lighting programs for commercial application. As lighting programs used during the growing and laying periods interact, their selection must be carefully coordinated. The primary concerns in selecting lighting programs are age of sexual maturity (average age of first oviposition) and the related effects on rate of lay and egg size. Additional concerns include effects on feed intake, body weight and composition, activity, flock uniformity, incidence of broodiness, prolapse of the oviduct and cannibalism. Genetic differences in response to lighting programs must also be considered, as well as possible gene-environment interactions that may affect rate of lay, egg size, shell quality and mortality.Ideally life-history lighting programs could be selected from among those tested under comparable environmental conditions, however, because each farm environment is unique and the array of possible life-history lighting programs is essentially infinite, the life-history lighting programs used are often modifications of recommended or tested programs. This review resulted in the following conclusions: 1. Step-down lighting programs can significantly delay onset of sexual maturity.2. Decreases in daylength at any age before a photostimulatory program is initiated will delay sexual maturity.3. Red light is not recommended for developing pullets because it sometimes results in reduced performance during the laying cycle.4. Later onset of sexual maturity results in larger egg size and may result in the production of fewer eggs in the subsequent laying cycle.5. When exposed to stimulatory photoperiods younger birds are slower to mature sexually than older birds.6. Earlier sexual maturity results when larger increases in daylength are given to photosentive pullets.7. Step-up lighting programs from 6L:18D can be used during the laying phase to shift the production curve to the right (lower peak; more eggs later).8. Step-up lighting programs can be used during the first half of the laying cycle to reduce energy use.9. Intermittent light (15 min L:45 min D during the light phase) can save electricity and improve feed conversion but the program is not recommended between the start of a stimulatory photoschedule and 36 weeks of age because reduced egg production will result.10. In light-controlled housing interrupted lighting programs (eg 8L:10D:½L:5½D) can save electricity during the laying cycle.11. In open housing 1 h light phases can be used to define subjective dawn and dusk with a resultant savings in electricity.12. Ahemeral lighting programs (28 h photoperiods) at end of the laying cycle can be used to improve shell quality without loss of egg numbers.