We're hoping to put any roos out of this batch in the freezer - but this would be our first time. They are a dual purpose bird (australorps). What is the difference between a fryer and a boiler? just age? I imagine that with this breed we may have to wait longer to make dinner worthwhile - up to six months? Is it worth trying to 'feed them up' or just let them be (ours free range). Thanks!