Department of Animal Sciences, University of Missouri, Columbia 65211, USA.
J Anim Sci. 2011 Nov;89(11):3572-9. doi: 10.2527/jas.2010-3302. Epub 2011 May 27.
A total of 54 finishing barrows (initial BW = 99.8 ± 5.1 kg; PIC C22 × 337) reared in individual pens were allotted to 1 of 6 dietary treatments in a 2 × 3 factorial arrangement of treatments with 2 levels of ractopamine (0 and 7.4 mg/kg) and 3 levels of dietary energy (high, 3,537; medium, 3,369; and low, 3,317 kcal of ME/kg) to determine the effects of dietary ractopamine and various energy levels on growth performance, carcass characteristics, and meat quality of finishing pigs. High-energy diets were corn-soybean-meal-based with 4% added fat; medium-energy diets were corn-soybean meal based with 0.5% added fat; and low-energy diets were corn-soybean meal based with 0.5% added fat and 15% wheat middlings. Diets within each ractopamine level were formulated to contain the same standardized ileal digestible Lys:ME (0 mg/kg, 1.82; and 7.4 mg/kg, 2.65 g/Mcal of ME). Individual pig BW and feed disappearance were recorded at the beginning and conclusion (d 21) of the study. On d 21, pigs were slaughtered for determination of carcass characteristics and meat quality. No ractopamine × energy level interactions (P > 0.10) were observed for any response criteria. Final BW (125.2 vs. 121.1 kg), ADG (1.2 vs. 1.0 kg/d), and G:F (0.31 vs. 0.40) were improved (P < 0.001) with feeding of ractopamine diets. Feeding of the low-energy diet reduced (P = 0.001) final BW and ADG compared with the high- and medium-energy diets. Gain:feed was reduced (P = 0.005) when the medium-energy diets were fed compared with the high-energy diets. Additionally, G:F was reduced (P = 0.002) when the low-energy diets were compared with the high- and medium-energy diets. Feeding ractopamine diets increased (P < 0.05) HCW (93.6 vs. 89.9 kg) and LM area (51.2 vs. 44.2 cm(2)). The LM pH decline was reduced (P ≤ 0.05) by feeding ractopamine diets. The feeding of low-energy diets reduced (P = 0.001) HCW when compared with the high- and medium-energy diets and reduced (P = 0.024) 10th-rib backfat when compared with the high- and medium-energy diet. These data indicate that feeding ractopamine diets improved growth performance and carcass characteristics, while having little or no detrimental effect on meat quality. Reductions in energy content of the diet by adding 15% wheat middlings resulted in impaired ADG, G:F, and 10th-rib backfat. There were no ractopamine × energy level interactions in this trial, which indicates that the improvements resulting from feeding ractopamine were present regardless of the dietary energy levels.
共有 54 头育肥阉公猪（初始 BW = 99.8 ± 5.1 kg； PIC C22 × 337），在单独的围栏中饲养，分为 6 种日粮处理的 1 种，采用 2×3 因子处理安排，2 个水平的莱克多巴胺（0 和 7.4 mg/kg）和 3 个水平的日粮能量（高，3,537；中，3,369；和低，3,317 千卡 ME/kg），以确定日粮莱克多巴胺和不同能量水平对育肥猪生长性能、胴体特性和肉质的影响。高能量日粮是基于玉米-豆粕-脂肪的日粮，添加 4%的脂肪；中能量日粮是基于玉米-豆粕的日粮，添加 0.5%的脂肪；低能量日粮是基于玉米-豆粕的日粮，添加 0.5%的脂肪和 15%的小麦麸皮。每个莱克多巴胺水平的日粮均按含有相同标准化回肠可消化赖氨酸：代谢能（0 mg/kg，1.82；和 7.4 mg/kg，2.65 g/Mcal ME）进行配制。在研究开始和结束（第 21 天）时，记录每头猪的 BW 和饲料消耗量。在第 21 天，对猪进行屠宰，以确定胴体特性和肉质。对于任何反应标准，都没有观察到莱克多巴胺×能量水平的相互作用（P > 0.10）。饲喂莱克多巴胺日粮提高了终重（125.2 与 121.1 kg）、ADG（1.2 与 1.0 kg/d）和 G:F（0.31 与 0.40）（P < 0.001）。与高能量和中能量日粮相比，饲喂低能量日粮降低了终重和 ADG（P = 0.001）。与高能量日粮相比，饲喂中能量日粮降低了增益：饲料（P = 0.005）。此外，与高能量和中能量日粮相比，饲喂低能量日粮降低了 G:F（P = 0.002）。饲喂莱克多巴胺日粮增加了 HCW（93.6 与 89.9 kg）和 LM 面积（51.2 与 44.2 cm2）（P < 0.05）。饲喂莱克多巴胺日粮降低了 LM pH 下降（P ≤ 0.05）。与高能量和中能量日粮相比，饲喂低能量日粮降低了 HCW（P = 0.001），与高能量和中能量日粮相比，降低了第 10 肋骨背膘（P = 0.024）。这些数据表明，饲喂莱克多巴胺日粮提高了生长性能和胴体特性，而对肉质几乎没有或没有不利影响。通过添加 15%的小麦麸皮降低日粮的能量含量，导致 ADG、G:F 和第 10 肋骨背膘降低。在这项试验中，没有莱克多巴胺×能量水平的相互作用，这表明无论日粮能量水平如何，饲喂莱克多巴胺所带来的改善都是存在的。
