Is there a B2 of the right strength that comes in capsule, caplet or pill form that you can just pop right into the beak? Remember, a chicken can swallow a mouse whole so a pill is no problem at all.
My chickens would not eat pellets either, but for a time that was the only kind of food we could get! We had one bag of crumbles left. So we mixed the pellets in their feeder half and half with their crumbles. And we cut out all treats! They ate the pellets simply becayse there was no other...