Growth-promoting implants consistently improve feedlot performance across all major production metrics. Compared to non-implanted cattle, implants increase dry matter intake by 4.2%, final body weight by 5.3%, average daily gain (ADG) by 12%, gain-to-feed ratio by 8.7%, hot carcass weight by 6.2%, dressing percentage by 0.3%, and longissimus muscle area by 5.3%. The tradeoff is a significant reduction in marbling score and a 7.7% increase in liver abscess prevalence. Journal of Anim…

Implant strategy selection hinges on production phase, sex class, and days on feed. For finishing steers fed 280 days, a single extended-release implant containing 200 mg trenbolone acetate (TBA) and 40 mg estradiol 17β administered at day 60 or day 80 post-arrival produces gain-to-feed ratios superior to day-0 administration or a reimplant program (Revalor-IS followed by Revalor-XS), while also reducing the proportion of steers treated once for bovine respiratory disease compared to day-0 and reimplant groups. USDA Agricultur… Steers implanted at day 0 or on a reimplant program had greater dry matter intake than delayed-implant groups, but inferior feed efficiency. USDA Agricultur… Fat thickness, marbling, and estimated empty body fat all differ by implant timing, confirming that timing influences carcass composition beyond growth alone. USDA Agricultur…

Recent FDA guidance now restricts reimplantation: a maximum of 2 implants can be used during finishing, and reimplantation within the same production phase is prohibited unless specifically stated on the implant label. Delaying a single extended-release implant 60–80 days after arrival is a viable strategy to comply with these guidelines without sacrificing growth performance or carcass quality in long-fed steers. USDA Agricultur…+1

For moderate versus aggressive reimplant programs in finishing steers, implant potency has a measurable but modest effect on ADG. An aggressive strategy (Revalor-IS [80 mg TBA / 16 mg estradiol] followed by Revalor-200 [200 mg TBA / 20 mg estradiol]) produced an ADG of 1.72 kg/day versus 1.66 kg/day for a moderate strategy (Revalor-IS followed by Revalor-S [120 mg TBA / 24 mg estradiol]). USDA Agricultur…+1 This performance difference is not mediated by rumen microbial community shifts — alpha- and beta-diversity of bacteria, archaea, and protozoa do not differ between aggressive and moderate strategies. USDA Agricultur…+1

Extended-release implants are a practical single-implant alternative to reimplant programs. Synovex ONE Grower (150 mg TBA / 21 mg estradiol benzoate), a moderate-potency extended-release implant, sustains growth performance for at least 200 days in steers and heifers fed in confinement. Translational A… Revalor-XH is a viable alternative to a two-implant Revalor-200/Revalor-200 program in heifers without meaningful loss of performance or carcass characteristics, though this equivalence appears partially dependent on dietary zinc concentration. Journal of Anim…

Zinc nutrition interacts with implant-driven growth and warrants attention in implanted cattle. Industry zinc supplementation (100 mg Zn/kg dry matter) improves interim performance during periods of peak hormonal payout compared to national recommendations (30 mg Zn/kg dry matter), and steroidal implants alter liver and circulating zinc concentrations. Animals+1 Zinc recommendations have not been updated since 1996 despite substantial improvements in growth from implants and genetic selection, and nutritional consultants commonly feed zinc at three times national recommendations. Journal of Anim…

In the cow-calf and backgrounding sectors, implants reliably improve growth without fertility penalties when used correctly. Suckling calves gain roughly 6–15% more ADG and wean approximately 10.4 kg heavier with implant use, and backgrounded cattle commonly realize 14–16% greater ADG. Veterinary Clin… A single calfhood implant administered to replacement heifers within the recommended 1–4 month window does not depress fertility; adverse reproductive effects arise primarily with very early, very late, or multiple implants. Veterinary Clin… Specifically, Synovex-C administered at approximately 2 months of age produces greater weaning, yearling, and pre-breeding body weights without affecting antral follicle count, reproductive tract scores, or final pregnancy rates. USDA Agricultur…

Breed type modifies the skeletal muscle response to implants. Bos indicus-influenced (Santa Gertrudis) steers and Bos taurus (Angus) steers show different calpastatin protein expression and gene expression patterns following implantation with 120 mg TBA / 24 mg estradiol, indicating that implant response is not uniform across genetic backgrounds. Journal of Anim…

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