Molecular and Physiological Mechanisms of Steroidal Implants in Beef Cattle: A Review

For decades, beef cattle producers have safely used steroidal implants as a low-cost, highly effective growth technology, delivering improvements in average daily gain (10 to 30%) and feed efficiency (5 to 15%) compared with non-implanted cattle. These improvements stem from increased skeletal muscle hypertrophy resulting from exposure to steroidal implants. This literature review investigates the history of commercially available estrogens, androgens, and progestins, as well as the release rates of steroidal implants and carrier technologies. It also examines the genomic and non-genomic mechanisms of action of these growth-promoting technologies, along with the physiological responses across successive production phases from suckling to harvest, which highlight how these tools modify growth trajectories and metabolic rates in beef cattle. Presenting up-to-date implant administration strategies that align implant potency, active ingredients, and duration of effectiveness with various production stages to optimize weight gain while preserving carcass quality and marbling.