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J. J. Ball, M. C. Hickinbotham, E. B. Kegley, J. T. Richeson, M. P. Rowe, J. G. Powell, 078 Comparison of Long-Acting or Conventional Growth Implants on Performance in Steers Grazed for 180 Days, Journal of Animal Science, Volume 95, Issue suppl_1, December 2016, Page 39, https://doi.org/10.2527/ssasas2017.078
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Abstract
Steers are often implanted with an androgenic hormone to repartition nutrients to increase protein synthesis and fat deposition while increasing feed efficiency and profitability. Long-acting implants with 200 d of activity are available that may simplify multi-implant regimens and reduce labor costs and cattle handling. The purpose of this study was to determine if steers grazing wheat pasture for 180 d and implanted with Synovex LA containing 150 mg trenbolone acetate and 21 mg estradiol benzoate in a novel, coated formulation would increase growth performance compared to steers implanted with either Ralgro or Revalor G. All cattle experienced at least a 14 d acclimation to pasture period before the start of the study. Crossbred beef steers (n = 345; BW = 252 ± 1.9 kg) were stratified by BW and randomly allocated to 1 of 3 implant treatments (Synovex LA, Ralgro, or Revalor G) based on d −1 BW in a one factor completely randomized design. On d 0, calves were administered the treatment implant according to label. Steers were grazed as a single group and rotated according to forage availability for 180 d on wheat pastures. Body weights were recorded on d −1, 0, 90, 180, and 181 to assess growth performance. Data were analyzed using the MIXED procedures of SAS with calf serving as the experimental unit with significance declared at P ≤ 0.05. Mean BW on d 90 was numerically less (P = 0.29; SE = 1.9 kg) in Synovex LA (302 kg) steers compared to either Ralgro (307 kg) or Revalor G (307 kg) implanted steers. Final BW were not different (P = 0.26; SE = 2.7 kg) but were numerically greater in Synovex LA (406 kg) steers than either Ralgro (400 kg) or Revalor G (401 kg) steers. Average daily gain from d 0 to 90 tended to be greater (P ≤ 0.07) in Ralgro and Revalor G steers compared to Synovex LA implanted steers. Average daily gain of Synovex LA (1.14 kg/d) implanted steers from d 90 to 180 was greater (P < 0.0001; SE = 0.02) than Ralgro (1.02 kg/d) or Revalor G (1.04 kg/d) steers. Overall, ADG tended to be greater (P = 0.06) in Synovex LA implanted steers compared to conventional implant treatments. The use of Synovex LA improved steer growth performance from d 90 to 180 while BW were similar for all implant treatments for the duration of the study.
