Most ranches in the Yampa Valley are cow/calf ranch operations, meaning the cows are kept year-round, and each year a calf is born and sold at weaning time. A cow will typically be productive for 10 years and then need to be replaced. Ranchers can either purchase a new cow or replace from within their own calf crop. Looking through their heifer calves, they will choose which ones to keep as replacements by looking at the body, birth weight, gai…