ABSTRACT For more than 60 y, beef cattle producers have safely used various types of growth-enhancing technology (GET) such as steroidal implants with anabolic activity and orally active beta-adrenergic agonists to increase skeletal muscle growth rate, improve carcass leanness, increase average daily gain (ADG), and alter dry matter intake (DMI) compared to non-treated cattle. Generally, the use of a GET increases ADG and only moderately affects DMI relative to non-treated cattle; subsequently, this enhances the rate of live weight gain relative to the amount of feed needed to achieve that gain, this is referred to as feed efficiency (G:F). When a producer chooses to utilize a GET, improvements in treated cattle over non-treated cattle are typically in the range of 8% to 28% for ADG and 5% to 20% for G:F. This review of the literature is intended to provide up to date insight into the mechanisms of how steroidal implants with anabolic activity enhance cattle growth and how these technologies have evolved since their introduction to U.S. beef producers nearly 60 y ago.

中文翻译：

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甾体植入物改善肉牛生长的机制：综述

摘要 60 多年来，肉牛生产者一直安全地使用各种类型的生长促进技术 (GET)，例如具有合成代谢活性的甾体植入物和口服活性 β-肾上腺素能激动剂，以增加骨骼肌生长速度，改善胴体瘦肉度，增加平均与未经处理的牛相比，日增重 (ADG) 和改变干物质摄入量 (DMI)。一般来说，使用 GET 会增加 ADG，并且相对于未处理的牛只适度影响 DMI；随后，这会提高相对于达到该增重所需的饲料量的活体重增加率，这被称为饲料效率 (G:F)。当生产者选择使用 GET 时，经过处理的牛比未经处理的牛的 ADG 提高 8% 到 28%，G:F 提高 5% 到 20%。