While your one rooster will eventually get to your 10 hens, I would not be comforatable with your ratio if I were selling the eggs as fertilized eggs to a buyer. A ratio of 1 roo to 5 hens would better assure you that the eggs will be fertile. You can use the one rooster you have, but rotate you hens every couple of weeks. This should keep the roo from tearing the hens backs and side up. Additionally, you need to trim the spurs on your roo before and during his time with his ladies. I also put saddles on my hens when intentionally breeding to sell fertilized eggs. It is much easier to protect them from the beginning than to notice the damage later and have to pull the hen from the roo. I have seen it take as long as a year to heal some mating wounds. If you are only concerned for your own purposes, stick with the one rooster and test the results in an incubator.