Replacement Heifer Development

segment of the integrated management program in an efficient beef cow production system. The main objective should be to develop an adequate number of heifers to a point where they reach puberty and are cycling regularly at the start of the breeding season. In addition, they should have adequate pelvic area to deliver a reasonable size calf unassisted. Because of her increased nutritional needs, one might also consider the first-calf heifer as part of the replacement heifer development program until she breeds back and weans her first calf. The replacement heifer represents the future profitability and genetic improvement of the cow herd. Assuming a restricted breeding season and a somewhat static weaning date each year, the age of calf at weaning has a large impact on pounds of calf weaned. This is particularly important if calves are sold at weaning. Therefore, it is important to the production unit that heifers conceive early in the first breeding season. Researchers at Montana State University concluded that heifers that conceived the earliest, immediately indicated their greater productive efficiency and lifetime production potential. Development of a replacement heifer is costly. The fact that she is growing and developing means that she must be managed and fed separately from the remainder of the herd. However, since she will not produce any economic return until she is approximately two and a half years of age (when she weans her first calf), this long period makes her an easy target for mismanagement. Because of the expense of the development phase, it makes weaning a calf in subsequent years from that properly managed and developed first calf heifer all the more critical. It is more economical to spread the development costs over several calves, rather than one if she is open after her first calf. The selection and development of replacement heifers can be divided into five phases: • Sire selection • Preweaning management • Heifer selection at weaning • Weaning to breeding • Gestation through parturition and rebreeding