What are you calling 'large number' of birds? 25? 50? 100? 500?
I grow birds to feed family and friends - I give away about 1/2 of what I 'grow' be it chickens, pumpkins, tomatoes, cucumbers, lettuces or whatever. For our family (with teen boys and friends), a 5-8# bird leaves very little 'left-overs'! However, this is totally dependent on family size. We're raising 25 CX to take us through the winter season. Of the 25 FR's we grew last spring, I've got just 6 left....so another batch must be 'grown'. That's only 12wks worth of chickens (if we have chicken 2x/week - which is typical). Looking at it from that standpoint, I 'grow' three batches of chickens/year to feed what feels like a small army of young men!
I do not grow birds to sell. However, there are folks in this section who do make a profit from this type of endeavor. And as a fairly new-to-this individual - I'm THANKFUL for all their wisdom, advice and help! Thank goodness for caring folks willing to type up an answer on a cold fall night!