Hi Sally, My chicken feed contains the cayenne pepper with some other herbs and they have not slowed down their production at all so far. Its my first year and I haven't fed them anything else, so I don't have any comparison, sorry!
I'm getting some of the pepper from an herb store for me. I was thinking of sharing it with the chickens. I ordered it during the Weekend sales. It was so much cheaper than the spice in the stores and this time of year chili goes over so well here.
And of all things the pepper is used in many home remedies and natural health things for people, everything from a cold tonic to jump start your labor cookies. But I still think I might have went a touch overboard and got enough to share with the chickens if I will get eggs in return.