Pumpkins are a treat that gives twice and you may or may not want to separate the two treats. You've got pumpkin seeds and pumpkin flesh. Between Halloween and early December I put a post on social media and go around an collect uncarved pumpkins that people set out as decorations for the holidays. I usually have a great response; this year was the best yet.
I give one descent sized pumpkin, halved and raw - seeds and all, for my 13 chickens about every third day.
The seeds will be gone and the flesh will be significantly eaten out, but not all gone. The rest goes to compost.
The good thing is that pumpkins last for several month (if not cut open or carved). As they start to turn even the least bit soft, I take those and get the seeds out and roast the flesh that is still good and use the puree to make a mash for them throughout the rest of the winter and into the spring. (Kept in freezer bag in deep freeze.)
Pumpkin seeds keep even longer (obviously). I use them in my own chicken feed as the protein supplement in lieu of soybeans, but the ratio is a little different as pumpkin seeds only have about 30-33% protein vs. 47% for soybeans. The good news is that pumpkin seed are packed full of other vitamins and minerals and antioxidants that make them a very good substitute and base for a homemade chicken feed. They even contain the lysine and methionine that chickens need, and in much greater amounts than a typical corn/soybean based diet.