My free ranging 8 week old Brown Leghorns barely eat any of the feed I put out. I call, and they will come and eat from my hand if they feel like it, but barely peck at the feeders now. I think they eat from my hand just to humor me and to stay on my good side so I will protect them. They are having a grand old time chasing bugs and tiny critters and seeds and stuff. I have others from the same batch in brood pens waiting for the coop to be finished and they eat eat eat those pellets! The appetite is there, but the choice is not, for now, for them. Given a choice, I think their instincts and cravings are determining what they eat. When foraging is less productive in the winter, I bet your birds start hitting the chicken chow pretty regular.
BTW freshly purchased and opened sack does not necessarily mean fresh feed. Smell and taste? Also try a different feeder. I gave the chicks a green plastic feeder after being accustomed to a red and white one and they wouldn't go near it. It took my free rangers a couple of weeks to start using the big galvanized waterer and feeder.
