is the hair actually turning colors or is it just dieing? when the black hair dies, it will turn a reddish brown. if thats the case, the shedder comb should take care of the problem. If it is legit red hair coming in, and its distracting or taking away from the calf, you can dye it. I'm planning on dying my March heifer with in the next week for her first show. She was black when she was born but now shes turning brown. I went to WalMart and got the cheapest hair dye they had. I had to get 5 boxes but if its just one spot then you should only need one box.