If I have a growout pen where the chickens will stay until they're 18 weeks or so, how much square footage is needed per bird? As it's just a temporary setup, I figure it's less than five.
By week 18 they will be heading towards being almost fully grown. If possible, I'd aim for at least 8sqft per bird in the run. Whilst the rule of thumb is 10sqft run space for adult, standard birds, that is a minimum, not an optimum size. You may possibly get away with 3sqft per bird in the coop (rule of thumb being 4sqft per bird). Its worth considering that the more space you can give your birds, the happier and healthier they will be.
If you get them outside in the grow out pen as soon as possible, they will be fully integrated into the main flock by the time they are 8 to 10 weeks. Adult birds really tend to ignore chicks under 6 weeks old. It's once they start to get older than that, that they are seen as a threat to the flock pecking order, making integration more difficult.
