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The objective was to evaluate the effect of days on feed (DOF) on performance and carcass characteristics of crossbred beef × dairy heifers. Beef × dairy heifers (n = 3,765; initial BW = 508 ± 8.55 kg) were blocked by arrival date and lot (n = 6 blocks at feedyard 1 and n = 7 blocks at feedyard 2) and randomly assigned to 1 of 4 DOF treatments of 323, 344, 362, or 385 when administered a Revalor-200 (200 mg of trenbolone acetate TBA and 20 mg of estradiol E2) on d 265. Dry matter intake was not affected by DOF, whereas final BW increased linearly from 593 to 655 kg. As DOF increased, ADG and gain: feed decreased quadratically. Hot carcass weight, LM area, calculated YG, and marbling score increased linearly as DOF increased. Across the 63-d serial slaughter period, hot carcass weight increased 0.67 kg/d. Dressing percentage and backfat thickness increased in a quadratic manner across DOF. Further, QG and YG distribution increased linearly as DOF increased. Liver abscess prevalence or severity did not increase with DOF. Implications and Applications Results of this study indicate that extending DOF by 63 d led to increased BW, hot carcass weight, LM area, marbling, YG, and QG but poorer ADG and feed conversion efficiency for beef × dairy crossbred heifers.
Husz et al. (Tue,) studied this question.