Thank you all for responding. Yes, the cookies are a very small part (less than 10%) of what I would have them (six, total) eat in one day. But I might still throw them into the compost pile (which the hens ultimately will get into, anyway).
Yes, just like people, they need a balanced diet - not too much junk food!
Thank you, Ol Grey Mare, for mentioning that you give your hens grower ration rather than layer ration. I switched my girls over when they hit four or five months of age, but was considering doing half and half of each of the two. I'll certainly implement that here soon.
Yes - they're hardier than many folks give them credit for. My co-workers who have hens think they need supplemental heat in the winter, and this being my first year with them (got them in October when they were only three months old), I did my research. Found that being allowed to go out, keeping humidity level low, and providing fresh water and perhaps a bit of scratch before they went to bed was the much better way to go! Extra bedding made them happy, too. No supplemental heat source, no frostbite, they're all happy and not pecking at each other. Here in Northern Colorado, we had one night at -20F, a few other nights pretty cold too.
Get this - the first pullet (a lovely Red Star named Lucy, after Lucille Ball) started laying on December 21st - the shortest day of the year! She has been laying reliably ever since, and two more have started as well. I've identified one as Titi, the Black Australorp (Titi is short for Tahitian Pearl), but have yet to figure out which of the six is the third one laying.
I, too, do this partially to reduce my wasteful impact on the earth, also to promote sustainability and local food sourcing in my corner of the world. My regular full-time job can be very stressful, and the hens do more for my state of mind than any therapist or pill ever could have.
Cheers!
Erika