I haven't seen many studies/discussion on the topic but I have a curious question: the hen's body takes cues from the day length on whether or not to "cycle"... So then, does supplemental lighting also have an impact as far as more "off season" broodiness?
***not trying to start a supplemental lighting discussion. Was just wondering if anyone has observed a difference.
I don't know the answer to that question, but I think it is important to realize that egg-laying chickens are very far what nature designed.
In nature, a bird will lay in a given season and will not lay outside that season regardless of the natural lighting. Wild birds usually lay one or two clutches in the spring when food is abundant; they don't lay at any other time.
For hundreds of years, chicken breeders have selected for abnormal egg-production cycles, with the hens that lay only a few eggs in the spring being removed from the gene pool in two ways--by active culling or by not producing many offspring to continue her lineage. The hens that produce many eggs throughout the year will not be culled, and they will produce many eggs giving them more opportunities to produce offspring and continue their genetic lineage.
The same holds true with broodiness with broodiness being selected against by culling. A chicken that broods in the fall and winter is going very much against Mother nature since fall or winter chicks will have a really hard time surviving.
I don't know that broodiness--the hormonal condition that triggers a hen to become a mother--is affected by light. In the wild it isn't as far as I know. When a hen sits on her eggs is determined by the species. Parrots sit from the day an egg is laid, so a clutch of eggs will have chicks that hatch over a week or more. The late hatching chicks will die unless something happens to the early chicks. Other species lay a full clutch before they become broody and sit on their eggs. Chickens, as far as I can tell, are a real mess as far as reproduction is concerned. There are many breeds that have absolutely no mothering instincts left.
I know from my experience with breeding Thoroughbred horses, we put a mare "under lights" in the winter to jump start her cycling. The added light will start ovulation in the dead of winter, which is very much against nature since a January or February foal would not survive in North America without human intervention. While it is normal to put a mare under lights to manipulate her ovulation cycles (basically egg laying), I have never heard of lights being used to increase maternal instincts, which I feel must be related to a brooding hen. It would be interesting to know if the production of the hormone oxytocin, one of the hormones involved in bonding, is affected by day length.
