Going Home one afternoon a pickup and trailer turned in front of me. I noticed that his back gate on his trailer was open, and a calf was standing at the opening. I turned on my flashers and tried to get around this vehicle keeping my distance from the back of it. The calf finally walked away from the opening, but a Heffer came to the opening and walked right out the back of the trailer and rolled end of end a few times. I had to completely stop in the middle of the highway to avoid hitting the cow. I was finally able to catch and pass this individual and got him to pull over so that no more cows or people were injured. Had I not been paying attention to my surroundings this could have ended very badly.