I just hatched 2 chicks and had to buy a 50 lb bag of feed. I don't plan on hatching any more until at least next spring. If I vacuum seal a few bags of it will it last a year stored in air tight in dark cool spot??
If vacuum sealed and stored in the ubiquitous cool, dark place (like in an air conditioned space) you could probably get away with saving it until next year.
But if it were me I'd just feed it on out until it's gone. Two chicks will largely finish a 50lb bag of chick starter by the time they reach point of lay. Seeing as how you are in Ontario even an open bag will keep longer than it would here in Florida where I am at. I keep my birds on starter until I see the first eggs then transition them over to layer.