A rooster can handle 10 hens, less than that and the hens can be overbred. If you have 4 roosters you would need 40 hens. Roosters aren't worth that much trouble. Unless you need fertile eggs to sell or hatch, you don't have to have a rooster at all. Hens will continue to lay just as many eggs, (albeit infertile) and will be much less stressed without a rooster harassing them.