One calf should only need one bag of milk replacer. I would recommend the medicated milk replacer which in our area of PA is $40. We begin weaning our calves when they are six-weeks-old. When they reach six-weeks of age, we feed them half the amount of milk replacer each feeding instead of going cold turkey. They should also be receiving calf feed of some kind. Our calves have feed placed in front of them as soon as they are a couple of days old. They can have up to 2 1/2 pounds of feed twice a day. If you are raising this calf for beef, it should have free choice fresh grass or hay.