Sorry this is terribly long, but please read. I moved up to New Hampshire from Florida 3 years ago, and brought my small flock of chickens with me. I tried to keep them outside for the winter, but my leghorns where getting frostbite and my bantams where acting cold when it was only about 25F during the day. The shed they where in is not insulated, but I blocked all drafts and even tried heating it, which didn't work. Eventually I gave up and put them in a big dog kennel in the basement. I was of course worried about them not getting enough sun, so I put them outside whenever it was warm enough, or onto the sun porch for a little while. They've been in there for three winters now, about 4 months each time. This spring I lost my white leghorn and my silkie to some type of illness, and now my black sexlink from the same flock seems to be in an early stage. It happens very slowly, starting with mild lethargy and reduced appetite. The main symptom seems to be that the crop cannot completely empty, but it's not impacted or sour (yet). Eventually they get diarrhea and the crop gets very large. I had the first two chickens put down, as they seemed to be slowly starving to death. I do have experience with sour crop, and they don't show the same symptoms, like drinking lots of water, bad smell, and immediately abnormal droppings. And it seems to take a while for the crop to get too full, so not like impacted. Could this have anything to do with a vitamin D deficiency? I bought them a D3 supplement last winter, but kind of late, so I continued for a little while in the spring, and just started again this year. My leghorn hens, which have both died now, where having problems with shell-less eggs both in winter and summer. I have lost two other chickens from this flock, to what seems to be crop infections, but it could be related. One of those hens, a leghorn, was sick last year but recovered, only to die from it this year. If you have any idea what this could be, please tell me. I hope I'm not killing my chickens by keeping them in the basement, but if I put them outside, I'm pretty sure they would freeze to death/get horrible frostbite. My leghorn rooster has a huge comb, and my seabright gets cold easily.