盐酸莱克多巴胺（Optaflexx）剂量和持续时间对育肥牛生长性能及胴体特性的影响。

Effect of ractopamine hydrochloride (Optaflexx) dose and duration on growth performance and carcass characteristics of finishing steers.

作者信息

Bittner C J, Crawford G I, Berger L L, Holt S, Pritchard R R, Platter W J, Van Koevering M T, Pyatt N A, Erickson G E

出版信息

J Anim Sci. 2016 Dec;94(12):5382-5392. doi: 10.2527/jas.2016-0807.

DOI:10.2527/jas.2016-0807

Abstract

Three experiments evaluated the effects of ractopamine hydrochloride (RAC) dose and duration on growth performance and carcass characteristics of feedlot steers. In total, 1,509 crossbred steers (530 kg initial BW [SD 22]) were used in a randomized complete block design using a 3 × 3 factorial treatment structure. Treatments consisted of RAC dose (0, 100, or 200 mg/steer daily) and duration (28, 35, or 42 d) of RAC feeding prior to harvest. Initiation of RAC dose was staggered (7 d apart) based on RAC duration, which resulted in common days on feed among treatments. Data from the 3 experiments were combined for statistical analyses. There were no RAC dose × duration interactions ( ≥ 0.85) for growth performance. Live final BW was not different ( ≥ 0.24) as RAC dose increased. Dry matter intake linearly decreased ( < 0.01) as RAC dose increased. Live ADG and G:F linearly increased ( ≤ 0.01) as RAC dose increased. Carcass-adjusted ADG and G:F linearly increased ( ≤ 0.02) as RAC dose increased. Compared with steers fed 0 mg RAC/steer daily, G:F was improved by 5.0 and 13.0% when steers were fed 100 ( = 0.31) and 200 ( = 0.01) mg RAC/steer daily, respectively. Hot carcass weight tended ( = 0.10) to linearly increase as RAC dose increased, with carcasses from steers fed 100 ( = 0.38) and 200 ( = 0.10) mg RAC/steer daily being 2.2 and 4.1 kg heavier, respectively, than carcasses from steers fed 0 mg RAC/steer daily. Increasing RAC dose linearly ( < 0.01) increased LM area and linearly ( = 0.02) decreased marbling score. Live final BW was not different ( ≥ 0.60) among RAC durations. Carcass-adjusted final BW, ADG, and G:F were not different ( ≥ 0.41) as RAC duration increased. Carcass traits did not differ ( ≥ 0.18) among RAC duration. Feeding 200 mg RAC/steer daily improved ADG, feed efficiency, and HCW. Increasing the feeding duration of RAC had no effect of growth performance or carcass characteristics. These data indicate that feeding 200 mg RAC/steer daily for 28 d improves steer growth performance.

摘要

三项试验评估了盐酸莱克多巴胺（RAC）剂量和持续时间对育肥牛生长性能和胴体特性的影响。总共1509头杂交育肥牛（初始体重530千克[标准差22]）采用3×3析因处理结构的随机完全区组设计。处理包括RAC剂量（0、100或200毫克/头·天）以及宰前RAC饲喂的持续时间（28、35或42天）。RAC剂量的起始时间根据RAC持续时间错开（间隔7天），这使得各处理间的采食天数相同。将三项试验的数据合并进行统计分析。生长性能方面不存在RAC剂量×持续时间的交互作用（P≥0.85）。随着RAC剂量增加，最终活体重无差异（P≥0.24）。随着RAC剂量增加，干物质采食量呈线性下降（P＜0.01）。随着RAC剂量增加，活体重平均日增重（ADG）和料重比（G:F）呈线性增加（P≤0.01）。随着RAC剂量增加，胴体校正后的ADG和G:F呈线性增加（P≤0.02）。与每天饲喂0毫克RAC/头的育肥牛相比，每天饲喂100（P = 0.31）和200（P = 0.01）毫克RAC/头时，G:F分别提高了5.0%和13.0%。随着RAC剂量增加，热胴体重呈线性增加趋势（P = 0.10），每天饲喂100（P = 0.38）和200（P = 0.10）毫克RAC/头的育肥牛的胴体分别比每天饲喂0毫克RAC/头的育肥牛的胴体重2.2千克和4.1千克。增加RAC剂量可使眼肌面积呈线性增加（P＜0.01），大理石花纹评分呈线性下降（P = 0.02）。不同RAC持续时间的最终活体重无差异（P≥0.60）。随着RAC持续时间增加，胴体校正后的最终体重、ADG和G:F无差异（P≥0.41）。不同RAC持续时间的胴体性状无差异（P≥0.18）。每天饲喂200毫克RAC/头可提高ADG、饲料效率和热胴体重。增加RAC的饲喂持续时间对生长性能或胴体特性无影响。这些数据表明，每天饲喂200毫克RAC/头，持续28天可提高育肥牛的生长性能。