EFFECT OF GROWTH RATE T H R O U G H 30 M O N T H S ON REPRODUCTIVE PERFORMANCE OF BEEF HEIFERS ~ A. T. Fleck 2, R. R. Schalles and G. H. Kiracofe

The effect of growth rate from birth through 30 months of age on the reproductive performance of Polled Hereford heifers calving as 2-year-olds was examined. Heifers with high gains during the first winter as weanlings had higher breeding efficiency when bred as yearlings, had larger pelvic areas as 2-year-olds, gave birth to larger calves, had less calving difficulty at first parturition and had higher breeding efficiency at the subsequent breeding. Calf growth to weaning was positively related to the first winter (weaning to yearling) gain of the dam. Heifers with high second winter gain had less calving difficulty at first parturition, slightly higher milk production and slightly higher breeding efficiency when rebred. Second winter gain of the dam had a high negative relationship with calf growth to weaning. Adequate growth from weaning to yearling was important for future production and reproduction through second breeding as 2-year-olds. (