We don't put any weaned animal back with the main herd. They are kept with animals their own age, heifers are bred to calve about 27-32 months, and they will stay in that group to breed back for their second calf. Then, if they make the "cut" to stay, they will get assimulated into the general herd . We don't feed alot but the first calf heifers will get a taste of grain a couple of times a week, about 1-2 lbs per head, to keep them quiet and coming to me so that I can easily check on them. All calve on pasture, and I can usually drive to 90% of where they are. I always keep a bucket of grain in the vehicle and when they are off by themself with a new calf, will put a little down on the ground, they will usually come over and eat and I can catch the calf and at least tag it and record what it is. Have had a heifer go back on a cow after 6 months and one went back on her mother when she had the next calf.... So, they now don't get that temptation. And any that are seen sucking another cow, or a heifer sucking another heifer, take a ride.