Flock blocks are very high in fat. I choose not to use them. As for corn or oats and the theory that they will keep the birds warmer in the winter, many threads have gone around and around about this topic, causing (pardon my pun) heated debates! A calorie is a calorie is a calorie. As long as the birds have good nutrition, they will be fine in the winter. Chicken feed is high in corn and other grains, so the assumption that giving them extra grains, either whole or cracked will make them warmer in the winter just does not make sense to me. And for that matter, when a body digests a large meal, a lot of peripheral blood gets diverted to the digestive system to distribute the digested nutrients, resulting in a temporary feeling of "being cold". Corn is also high in fat. While extra fat in the body might be a good thing during the winter, too much visceral fat can cause egg laying issues. Some hens when processed carry an incredible amount of deep yellow visceral fat from a diet too high in treats, scratch grains with the large amount of corn being the chief offender.