First-calf heifers with high-growth expected progeny differences (EPDs) are often slower to breed back a second time, according to a study by the National Cattlemen’s Beef Association. In each of the seven participating breeds, females in the top 20 percent for yearling-weight EPD were compared to females of the same breed in the middle 20 percent and bottom 20. In the 250,000 females evaluated in both Continental and English breeds, females with the highest yearling-weight EPDs had longer average calving intervals.