Well cared for cows can live up to twenty years. However, by the time a cow reaches the age of 12 to 15 years, she may be less profitable to keep. Many cows begin missing heat cycles, and the cycles that they do experience may be less fertile. Additionally, older cows may struggle with keeping body condition, which can seriously affect their ability to become pregnant and maintain a pregnancy. If you have cows that are getting up in years, it may be time to give some thought to raising some heifers as potential herd replacements. Raising your own herd replacements has a distinct advantage over buying cows from another farm. When you raise your own heifers, you will know exactly how the cows have been treated, who their dams and sires were, and if they are healthy or not. However, the disadvantage of raising your own replacement heifers is that you have to feed them for at least two years before they will be paying their own way. How Do They Look? First, thoroughly study the appearance of the group of heifers that you are considering. Don\'t make the mistake of choosing heifers based only upon size. The biggest calves won\'t necessarily be the best producers. Choose a heifer that is feminine in appearance and graceful in body form. Her legs and feet should be sound, and she should walk smoothly. What About the Dam? Heifers often perform similarly to their mothers. All things being equal, keep heifers that were birthed from your best cows. Certain traits like milk and temperament are very heritable from one generation to the next, so you should keep heifers from cows that give the most milk and are the most calm. Not only are these heifers more likely to become the easiest cows to handle, but they will probably wean off the heaviest calves when they do give birth. Ask the Vet When you are evaluating a large group of heifers, you may want to get the vet to palpate the reproductive tract of each one. The vet can give you more information about the pubertal development of the heifer. He can also estimate the pelvic size of the young cow. Heifers with narrow pelvises are more likely to experience birthing difficulties that would require your assistance. Cows that need assistance in calving are usually slower to breed back in the first few months after calving. Therefore, you should not keep a heifer with a small pelvis. Watch Her Heat Cycles If the heifer is not cycling by the time she is 13 months old, she may not be able to breed when she is 15 months old, the ideal time to breed a cow for the first time. Keep in mind that the first couple heat cycles are usually not very fertile. Check the average time for puberty for your breed of cattle. If your heifer is lagging behind the group, she could calve late for several years until you can get her on the right schedule. Whether you are raising registered stock or a crossbred commercial herd, you should consider carefully which heifers to keep for herd replacements. The smart farmer will think these matters over carefully so that he will be continually improving his herd.