Post-weaning performance and carcass characteristics of steers implanted during the suckling phase with a combination of estradiol benzoate and trenbolone acetate

Authors: GENTRY, W - SOUTH DAKOTA STATE UNIVERSITY; PRITCHARD, R - SOUTH DAKOTA STATE UNIVERSITY; HALES PAXTON, KRISTIN

Submitted to: Proceeding of Plains Nutrition Council Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 3/21/2018
Publication Date: 3/28/2018
Citation: Gentry, W.W., Pritchard, R.H., Hales, K.E. 2018. Post-weaning performance and carcass characteristics of steers implanted during the suckling phase with a combination of estradiol benzoate and trenbolone acetate [abstract]. In: Proceedings of Plains Nutrition Council Spring Conference, April 5-6, 2018, San Antonio, TX. p. 118-119.

Interpretive Summary:

Technical Abstract: An experiment was conducted to examine the effects of administering an extended release, estradiol benzoate and trenbolone acetate combination implant to suckling steer calves on post-weaning performance and carcass characteristics. In early May, suckling steer calves were either not implanted (NONE) or were implanted with 21 mg estradiol benzoate and 150 mg trenbolone acetate (Synovex One Grass; ONE-G). Steer calves were predominantly 30 to 60 d of age when implants were administered. Steers were weaned in late October and enrolled in a 44 d receiving experiment (177 to 221 d post-suckling implant administration) where no implants were administered. At the conclusion of the receiving experiment 55 steers (BW=746 ± 8 lb.) were sorted into pens based upon suckling implant exposure and BW. All steers were implanted with a Synovex Choice on d 5 {226 d post-suckling implant administration) and a Synovex Plus on d 85. Steers were fed common diets (167 d) and were shipped to a commercial abattoir on a common day when overall mean population rib fat depth was estimated to be 0.5 inches. Carcass data were collected via the video image analysis software at the packing plant. Performance'' data were analyzed as a completely randomized design using the GLM procedure of SAS with' pen as the experimental unit. Carcass data were analyzed similarly with steer as the experimental unit. Quality Grade distributions were compared via the FREQ procedure of SAS. Steers implanted with ONE-G were heavier than NONE steers at the onset of the experiment (760 vs. 733 ± 2.1 lb; P < 0.01). By d 85 there were no differences in BW (1033 and 1033 lb). On a cumulative carcass adjusted basis NONE steers were more efficient than ONE-G steers (5.38 vs. 5.78 ± 0.113 F:G; P = 0.05). No difference in cumulative DMI was observed (P = 0.26). Steers implanted with ONE-G tended to have a larger REA than NONE steers, despite being implanted similarly in the feedlot (14.15 vs. 13.67 ± 0.177 in2; P = 0.06). No differences were observed for other carcass characteristics or Quality Grade (P > 0.20). Percent empty body fat at harvest was similar for NONE and ONE-G steers (P > 0.20). The ONE-G implant is labeled for 200 d of implant coverage. To study the potential anabolic effects of ONE-G in the feedlot, we chose not to re­implant steers until 226 d post-suckling implant administration. Therefore, the ONE-G steers did not have continuous exposure to an active implant. Differences in early performance may be a consequence of the discontinuous exposure to anabolic agents. Administering ONE-G during the suckling phase did not diminish carcass quality. Since no adverse consequences were evident, future work should evaluate implant strategy options to follow ONE-G in suckling calves.