The challenge to the beef herd manager is to ensure that the cows have enough body reserves to meet priority demands such as rebreeding. Many beef cows have such high body maintenance and lactation requirements that adding body fat during the nursing phase is impossible. The most efficient time to add body fat is from weaning to calving. During this phase the only demands are for body maintenance and fetal development. Heifers due with their first calf can have calving difficulty if they have a body condition score above six.
Most producers operate so that cows are more likely to be thin than fat.
The only other reason for a beef cow to become fat is that her nutrient intake exceeds her demand for all needs, so most beef cattle operations have few problems due to fat cows. Thin cows, on the other hand, are a major problem in beef herds. The most prominent animal in this category is the first-calf heifer. Recall that the nutrient demands in priority order were body maintenance, lactation, growth, breeding and fetal development. The reproductive processes are at the bottom of the list, so the first-calf heifer has demands for body maintenance, lactation and growth to fill before reproduction.