Is it for sure a rooster? He has a prolapsed vent, usually more common in hens, and there may be damage from being vent pecked. How much of his intestines is hanging out? Is it damaged? He may need to be put down if it is damaged and cannot be pushed back inside. Right now I would lubricate it with any oil, vaseline, or ointment or spray Vetericyn on it to keep it from drying out. Do you have other roosters or cockerels?