The effects of five different implant programs on the health outcomes, growth performance, and carcass characteristics of lightweight beef steers

Authors: LINE, DALTON - Texas Tech University; WORD, ALYSSA - Cactus Research; KARR, KENDALL - Cactus Research; HOLLAND, BEN - Cactus Research; WALTER, LEE-ANN - Merck Animal Health; NICHOLS, WADE - Merck Animal Health; HUTCHESON, JOHN - Merck Animal Health; Sanchez, Nicole; Broadway, Paul; HALES, KRISTIN - Texas Tech University

Submitted to: Applied Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2025
Publication Date: 10/1/2025
Citation: Line, D.J., Word, A.B., Karr, K.J., Holland, B.P., Walter, L.J., Nichols, W.T., Hutcheson, J.P., Sanchez, N.C., Broadway, P.R., Hales, K.E. 2025. The effects of five different implant programs on the health outcomes, growth performance, and carcass characteristics of lightweight beef steers. Applied Animal Science. 41(5):502-511. https://doi.org/10.15232/aas.2025-02695.
DOI: https://doi.org/10.15232/aas.2025-02695

Interpretive Summary: The beef industry has been improved by methods like the use of growth-promoting implants. Reimplantation used to be common practice, especially in cattle fed for more than 200 days. However, new guidelines forbid reimplantation within the same production phase unless stated on the implant label. Delaying applying implants beyond feedlot arrival could be a viable strategy to follow the new implant guidelines. Scientists with the USDA-ARS and industry and university collaborators designed a study to evaluate 5 different implant programs on cattle performance. Results from this study found differences in sickness when cattle were given an implant at arrival versus delayed 60 and 100 days. Also, there were differences in various performance parameters relative to implant strategy. Thus, delaying implantation may be an option to meet new guidelines without negatively impacting growth in steers. These data will be of interest to beef cattle scientists and producers.

Technical Abstract: Our objective was to evaluate 5 different implant programs on the health outcomes, growth performance, and carcass characteristics of lightweight beef steers. Crossbred steers (n = 3,817; initial BW 195 ± 1.1 kg) were used in a randomized complete block design and fed to a common number of d on feed (280 d). Steers were blocked by time of arrival (n = 10 blocks) and assigned randomly to 1 of 5 treatments: 1) 200 mg of trenbolone acetate (TBA) and 40 mg of estradiol 17ß administered on day 0 (XS0); 200 mg of trenbolone acetate (TBA) and 40 mg of estradiol 17ß administered on day 60 (XS60); 200 mg of TBA and 40 mg of estradiol 17ß administered on day 80 (XS80); 200 mg of TBA and 40 mg of estradiol 17ß administered on day 100 (XS100); and 80 mg of TBA and 16 mg of estradiol 17ß administered on day 0 followed by 200 mg of TBA and 40 mg of estradiol 17ß administered on day 80 (IS-XS). Steers treated once for bovine respiratory disease (BRD1) was less in XS60 and XS100 than XS0, XS80, and IS-XS (P = 0.03). No difference was noted in mortality among treatments (P > 0.25). Steers in XS0 and IS-XS had greater DMI than XS60, XS80, and XS100 (P < 0.01). Gain:feed differed among treatment, in which XS60, XS80, and XS100 had greater gain:feed than XS0 and IS-XS, both with dead and removed steers included (P < 0.01) and excluded (P = 0.05). No differences were observed in carcass traits, except in fat thickness (P < 0.01), marbling (P = 0.05), and estimated empty body fat (P = 0.01), indicating that implant timing influences carcass characteristics. In high-risk, long-fed steers, delaying Revalor-XS for 60 or 80 days after arrival does not differ from using a reimplant strategy in which Revalor-IS was followed by Revalor-XS or administering Revalor-XS on day 0. Delayed implantation with an extended-release implant can meet new FDA guidelines without negatively affecting growth performance or carcass quality in long-fed steers.