Effects of Supplement Type on Growth and Pregnancy Rate of Yearling, Brahman-Crossbred Heifers

The effects of winter supplement type on growth and pregnancy rate of fall-born, yearling heifers was investigated over 2 consecutive years. During both years, heifers were stratified by breed (Braford and Brangus-crossbred) and BW and randomly assigned to one of two treatments consisting of (1) wheat middling-based range cube, or (2) molasses-cottonseed meal slurry (n=34 and 24 heifers/treatment for Year 1 and 2, respectively). Supplements were fed three times weekly at rates to achieve a target of 3.25 and 0.75 lb of supplemental TDN and CP daily, respectively. Four limpograss (Hemarthria altissima) pastures were utilized each year. All heifers were allowed free-choice access to stargrass (Cynodon nlemfuensis) hay during periods of limited pasture forage availability. During a 70-d breeding season, heifers were combined by group and exposed to mature Angus bulls. Bulls were rotated among pastures each week. Individual heifer BW and hip height were collected at the start of supplementation and at the start and end of the breeding season. Pregnancy rate was determined by transrectal ultrasonography in late April of each year. Supplement type did not affect heifer ADG (0.97 and 1.04 lb/d for molasses-slurry and range cubes, respectively). Heifers consuming molasses-slurry had a greater overall pregnancy rate compared to heifers consuming range cubes (76.3 vs 49.2% pregnant). Irrespective of treatment, Brangus-crossbred heifers had a greater pregnancy rate than Braford heifers (73.2 vs 46.8%). These data indicate that yearling heifers, supplemented with molasses-cottonseed meal slurry, may have increased pregnancy rates compared to heifers supplemented with a wheat middling-based range cube. This response appears to be independent of heifer ADG.