These results of a new study at the University of California-Davis demonstrate that providing 12 hours of light per day during incubation can reduce the stress susceptibility of broilers post-hatch.

That is the conclusion of Gregory S. Archer and Joy A. Mench in their paper in the current issue of Poultry Science.

They explain that providing light during incubation has been shown to decrease bilateral physical asymmetry of broilers post-hatch, which may indicate that early light stimulation reduces later stress susceptibility.

Their experiment evaluated the effects of lighting during embryogenesis on other measures of stress responsiveness in broilers.

Cobb 500 eggs (n=1,404) were incubated under 0L:24D, 1L:23D, 6L:18D or 12L:12D; the light level was 550 lux. The broilers were then raised in floor pens under a 12L:12D lighting regimen and various stress parameters were measured during weeks 3 to 6 of age.

There was an effect of incubation lighting regimen on post-hatch stress responses. Following one hour of crating, the change in corticosterone (CORT) concentration was less in the 12L:12D (−0.06ng per mL; P<0.05) treatment than all other treatments (pooled mean = 0.24ng per mL); however, there were no treatment differences in CORT response to adrenocorticotropic hormone administration (pooled mean pre- versus one hour post-administration = 17.5ng per mL; P>0.05).

Anti-keyhole limpet haemocyanin titres were higher in the 12L:12D birds (92,395 units per mL; P<0.05) than all other treatments (pooled mean = 68,407 units per mL) on day 1 post-crating.

Additionally, Archer and Mench commented that composite asymmetry scores were lower in the 12L:12D treatment (0.92mm) than all other treatments (pooled mean = 1.14mm; P<0.05).

Reference

Archer G.S. and J.A. Mench. 2013. The effects of light stimulation during incubation on indicators of stress susceptibility in broilers. Poult. Sci. 92(12):3103-3108. doi: 10.3382/ps.2013-03434