The best thing to do in these situations is to try and reunite the calf with its mother. It is very important for the calf to get colastrum, the first milk the mother gives, because of the nutrients it provides to the calf. If the mother will not allow the calf to suck, try penning the cow and milking her, then bottle feed the calf with the milk. If that is not possible or if the mother has died, you will need to buy a product such as Colostrex or First Milk. If the calf is weak, you may also want to give it a product like Kick Start. This is a vitamin and electrolyte package. Feed the Colostrum for the first 3 days if the calf did not receive any from the mother. After that, there are a few things you can do. If you want to raise the calf, you will need to buy a powdered milk supplement such as Nurse Chow and bottle feed it twice daily for a about three weeks. Then you can cut it back to once daily for the next week. I would also recommend feeding a product like Calf Startena after the 4th day through 2 months of age. Be sure that the calf has plenty of fresh, clean water available at al times and a source of grass or hay.