What’s the optimal ratio of roosters to hens?

Most backyard chicken keepers say the optimal ratio of roosters to hens is about 1:12, and 1:6 for Silkie Bantams. With too many roosters, hens will lose the feathers on their backs, and in some cases can be so rough that the hens begin to bleed.

Watch this clip to see when there are too many roosters, they will gang up on a hen.