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Performance of Layers Given Two-Hour Midnight Lighting as Growing Pullets

Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario N1G 2W1 Canada

Correspondence: S. Leeson, E-mail: Sleeson{at}uoguelph.ca

Two experiments were conducted to record layer performance of growing pullets that had received various midnight lighting treatments. In these studies, pullets were grown on 12 h of light (6:00 a. m. to 6:00 p. m. ) in experiment 1 and on 8 h of light (7:30 a. m. to 3:30 p. m. ) in experiment 2. Some pullets received 2 h of supplemental light at midnight (12:00 a. m. to 2:00 p. m. ) from either0 to 18, 4 to 18, 8 to 18, 12 to 18, 0 to 12, 0 to 8, or 0 to 4 wk. Each rearing treatment was tested with eight replicate groups of four adjacently and individually caged birds. From 18 to 70 wk of age, the greatest number of eggs (317 or 315) were produced by pullets given midnight lighting from 0 to 18 or 4 to 18 wk, respectively. Introducing the extra light late in the growing period (12 wk) induced early maturity and had a negative effect on late cycle egg production. Most other production parameters were little influenced by the midnight lighting treatments. The only detrimental effect of midnight lighting occurred when it was used only during the late rearing period, likely because it induced sexual maturity too early.

Key Words: egg production • midnight lighting • pullet • sexual maturity