Yes a price reduction and a notice on it saying its out of date would be good but thats not happening, people are buying old feed unaware its out of date.
Whole grains will keep for months if not years just fine but Starter crumb and other milled feeds 5 months out of date will have lost most their vitamin, mineral and nutritional value, it'll look ok and they'll eat it, it just won't be doing the birds much good