Dear Dr. Sharp, I had just come across your new project. Years ago I ( and Dr. Vibhakar Kotak) had collaborated with you for LH and T profiles of male Baya weavers in both breeding and non-breeding seasons that resulted in a paper published in the Journal of Zoology (London). Which birds are you looking at for hormonal profiles under different lighting patterns? I am curious to know if the hormonal profiles in birds are under the influence of lighting along with their reproductive status although it is primarily the light that induces the reproductive activity in seasonal breeders. Does the environmental lighting continue to influence the hormonal profile even after the birds enter the reproductive mode? Thank you for your attention. - NARASIMHACHARYA. A.V.R.L.
Light levels (day length) is associated with moult in domestic fowl and other birds. In 1950 lit (Morris) and others address the issue as to when it is best to hatch domestic chicks with a view to optimising egg production via avoiding moult. the idea / reality was that adult hens tend to moult after day length exceeded 17hrs in N Latitudes. However younger birds who started laying before the critical mid summer period could skip moult an continue to lay for a long laying period (provided they had some artificial light during the short winter days).
Thus there appears to be a number of factors interacting,
age of bird,
reproductive phase,
and day length.
You would be wise to consult the old domestic species literature (Morris) ie pre 1960's to get a good starting handle on this issue.
J. P. Kent
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