Effect of a 28 Hour Light:Dark Cycle on Egg Shell Quality of End-of-Lay Birds

Sixty-two week old Single Combed White Leghorn (SCWL) hens were subjected to either a 24 hr (14L:10D) or 28 hr (14L:14D) day. Results from 30 individually caged birds on each treatment showed that the ahemeral light cycle resulted in an immediate decrease in egg shell deformation and increase in egg size. Egg production was not affected. Improvement in egg size is discussed in relation to possible dietary modifications. It is concluded that egg shell quality of end-of-lay birds can be substantially improved by imposition of a 28 hr light:dark cycle.