Gray Stripe sunflower seeds have a much harder shell and are hard for the birds to digest. These are the ones that humans usually eat. You will notice that general bird seed always contains BOSS rather than Gray Stripe. I tried feeding some gray stripe seeds to be birds last year (fresh picked from the garden) and they were not very interested. The BOSS seeds they went crazy over. I would pick 2 or 3 flower heads and place them in the run (with 17 pullets). The would pick all of the seeds out of the head in an amazingly short time. No need for you to remove the seeds from the head. They are more than capable. I would give them the seed heads about 3 times a week. Within a couple of weeks their feathers were shiny and soft.
I grew BOSS seeds just for the chickens last year. I believe I grew 3 20' rows. I planted more than twice that this year. I may have to replant them though. We had a very wet May and now June is setting records for rainfall. We have another storm heading this way on Wed. Seeds are rotting in the ground. If they do germinate they only grow a primary set of leaves and then quit growing (due to cool temperatures). Eventually slugs, birds, and wild rabbits eat the seedlings. It is a difficult gardening year for people in Western Oregon and Western Washington this year. Some people have not even gotten their gardens tilled yet.
We had a sunflower pop up in our garden this year, we just harvested the head, I have to wait until my girls are older to give them the seeds but we planted quite a few around so hopefully we will have a good crop going! I think the original somehow came over from our neighbors yard- she is a very nice lady, grows lots of cactus and sunflowers. What are the benefits of BOSS?