Experiment 1. Forty-eight Simmental-An- gus crossbred yearling heifers (246 + 21 kg) were assigned randomly to four treatments: 1) control (no implants), 2) Synovex-H 3 implants on d 1 and 84, 3) a 15-cm testosterone propionate implant on d 1 and a second 15-cm testosterone propionate implant on d 84 and 4)two 15-cm testosterone propionate implants on d 1. Testosterone implants were removed 35 d prior to slaughter. After a 21-d adaptation, the heifers were weighed full on two consecutive days at the start and the end of the 157-d study and at 28-d intervals during the study.