Avendaño-Reyes L, Torres-Rodríguez V, Meraz-Murillo F J, Pérez-Linares C, Figueroa-Saavedra F, Robinson P H
Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Ejido Nuevo León, Baja California, México.
J Anim Sci. 2006 Dec;84(12):3259-65. doi: 10.2527/jas.2006-173.
The impact of using 2 beta-adrenergic agonists in feedlot cattle fed finishing diets was evaluated using 54 steers (45 crossbred Charolais and 9 Brangus) initially weighing 424 +/- 26.6 kg in a randomized complete block design with 3 treatments and 6 blocks (i.e., 18 pens with 3 steers per pen). Response variables were feedlot performance, carcass characteristics, and meat quality. Treatments were 1) control (no supplement added); 2) zilpaterol hydrochloride (ZH; 60 mg.steer(-1).d(-1)); and 3) ractopamine hydrochloride (RH; 300 mg.steer(-1).d(-1)). The beta-agonists were added to the diets during the final 33 d of the experiment. The groups of steers fed ZH or RH improved (P < 0.01) ADG by 26 or 24%, respectively, compared with control steers. Steers supplemented with RH consumed less (P = 0.03) DM (8.37 kg) than control steers (8.51 kg), whereas intake was similar (P = 0.37) for ZH and control steers. Addition of either beta-agonist to the diet considerably improved (P < 0.01) the G:F (ZH, 0.253 and RH, 0.248 vs. control, 0.185). Hot carcass weight and carcass yield were enhanced (P < 0.05) with both beta-agonists. The LM area was increased (P = 0.026) by ZH (75.2 cm(2)), but that of RH (72.2 cm(2)) was similar (P = 0.132) to the control steers (66.8 cm(2)). Meat from the ZH- (P = 0.0007) and RH- (P = 0.0267) supplemented steers had greater shear force values than control steers (ZH = 5.11; RH = 4.83; control = 4.39 kg/cm(2)). Variables related to meat color indicated that both beta-agonists led to a similar redness of the LM area related to the control group. In general, feedlot performance was greatly enhanced by beta-adrenergic agonists, and meat tenderness from treated animals was classified as intermediate. Furthermore, meat color was not altered by beta-agonist supplementation.
采用随机完全区组设计，用54头阉牛（45头夏洛莱杂交牛和9头婆罗格斯牛）进行试验，初始体重为424±26.6千克，设3种处理，6个区组（即18个围栏，每个围栏3头阉牛），评估在育肥牛场中给育肥期日粮添加两种β-肾上腺素能激动剂的影响。反应变量包括育肥牛场性能、胴体特征和肉质。处理方式为：1）对照（不添加补充剂）；2）盐酸齐帕特罗（ZH；60毫克·头⁻¹·天⁻¹）；3）盐酸莱克多巴胺（RH；300毫克·头⁻¹·天⁻¹）。在试验的最后33天，将β-激动剂添加到日粮中。与对照阉牛相比，饲喂ZH或RH的阉牛组平均日增重（ADG）分别提高了26%或24%（P<0.01）。补充RH的阉牛干物质（DM）摄入量（8.37千克）低于对照阉牛（8.51千克）（P=0.03），而ZH阉牛与对照阉牛的摄入量相似（P=0.37）。日粮中添加任何一种β-激动剂均可显著提高料重比（G:F）（ZH为0.253，RH为0.248，对照为0.185；P<0.01）。两种β-激动剂均提高了热胴体重和胴体产量（P<0.05）。ZH使眼肌面积增加（P=0.026）至75.2平方厘米，而RH组（72.2平方厘米）与对照阉牛（66.8平方厘米）相似（P=0.132）。补充ZH（P=0.0007）和RH（P=0.0267）的阉牛肉剪切力值高于对照阉牛（ZH=5.11；RH=4.83；对照=4.39千克/平方厘米）。与肉色相关的变量表明，两种β-激动剂使眼肌部位的红色程度与对照组相似。总体而言，β-肾上腺素能激动剂极大地提高了育肥牛场性能，处理组动物的肉嫩度为中等。此外，补充β-激动剂未改变肉色。
