Blood stop, or if you have none then corn starch or even flour will help stop the bleeding. Turmeric powder (the spice) can also work. It's going to be very painful for him until it hardens up and dries out, so be gentle as possible. He may not eat or drink well while it's so painful, so keep an eye on him. Mix his feed with some water to make a mash and put in a deep, open raised dish to make it easier for him to feed. The softer feed will be less painful for him also and the extra water will help with hydration. It should be feeling better in a few days. Once it's stopped bleeding and is easier to see, another picture if you think needed. If this was from fighting with another roo, I'd separate them.