At 0800 mountain time, a Cessna 182K struck a bull during takeoff from Young Airstrip. The pilot was not injured. The pilot said he had just rotated and was about six feet agl when a bull wandered onto the runway. The right main gear struck the animal. The pilot continued his flight to Payson, Ariz., where he landed uneventfully. Post-flight inspection found the right main gear box was pulled loose.