I have a couple of Dexter cows (bull and heifer). I feed them chop feed - the bull is 1 1/2 and the heifer is 2 1/2 and pregnant. My vet told me just to feed the heifer (I did not have the bull at that time) about 3/4 of a cup a day but they seem like they are starving. They do get hay and are accessible to the pasture - until we get the snow. Is this amount the right amount or should I be feeding them more - or less?