How old are these chickens? If they're chicks, they'll be very slow to try something new. If they're older chickens who've never seen a squash before, it shouldn't take too long for them to get excited about it. Especially the seeds should be speaking to them in short order.
Make sure you've split the squash in two in order for the pulp and seeds to be completely accessible. By the way, a safe way to cut a large squash open is to use a hand saw, not a knife. It will prevent an unscheduled visit to the ER.