Calving ease is influenced by several factors: age, heifer development, genetics (sire and dam), nutrition during the 3rd trimester, calf presentation at delivery, temperature and time of year, and other factors. Heifers should be developed to reach at least 85% of their mature weight before calving. During the 3rd trimester heifers should be fed to gain about 0.8 to 1.2 pounds per day in most cases. Underfeeding heifers can lead to more calving problems, delayed rebreeding, and weaker calves. Calves born during the fall will be a few pounds lighter than those born in the winter or spring.