I have a calf now 2 ½ weeks old. He will suck from a bottle if you stick nipple in his mouth. The cow would let him nurse if he could find a teat. The calf walks around the cow nudging her with his nose. I have put her teat in his mouth but he doesn't know what to do. He is in the pasture with other cows and calves, should I separate him and feed him grain? How long should I bottle feed him?