Department of Animal Science, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
J Anim Sci. 2010 Jul;88(7):2486-99. doi: 10.2527/jas.2009-2428. Epub 2010 Feb 26.
Heifers with expected increased risk of bovine respiratory disease (BRD; n = 360; initial BW = 241.3 +/- 16.6 kg) were assembled at a Kentucky order-buyer facility and delivered to Stillwater, OK, in September 2007 to determine the effects of clinical BRD observed during preconditioning on subsequent feedlot performance, carcass characteristics, and meat attributes. During a 63-d preconditioning period, morbidity and mortality attributed to BRD were 57.6 and 8.6%, respectively. Immediately after preconditioning, heifers were grouped according to health outcome category and allotted to finishing pens (5 to 7 heifers/pen). Heifers were never treated for BRD (0X; n = 9 pens), treated 1 time (1X; n = 9 pens), 2 times (2X; n = 6 pens), 3 times (3X; n = 6 pens), or designated as chronically ill (CI; n = 2 pens). Arrival BW was not different (P = 0.21) among treatment categories. However, disease incidence during preconditioning decreased (P < 0.001) growth, resulting in BW of 318, 305, 294, 273, and 243 kg for 0X, 1X, 2X, 3X, and CI, respectively, at the start of the finishing phase. Estimates on the LM, taken by ultrasound on d 65 and 122, were combined with BW and visual appraisal to target common average endpoint within category and block. On average, heifers were slaughtered on d 163 for 0X, 1X, and 2X, d 182 for 3X, and d 189 for CI (P < 0.01). Final BW was similar (P > or = 0.18) for heifers treated 0, 1, 2, or 3 times, but heifers deemed CI weighed less (P = 0.01) than 3X heifers. Considering the finishing phase only, ADG was linearly increased (P < 0.001) with increasing BRD treatments, but was linearly decreased (P = 0.003) as BRD treatments increased from arrival to slaughter. Therefore, G:F was greater (P = 0.007) for CI than 3X and linearly increased (P = 0.002) from 0X to 3X. Similar to BW, HCW was less (P = 0.03) for CI than 3X. Marbling score tended (P = 0.06) to decrease linearly as the number of treatments increased, but no other differences (P > or = 0.24) in carcass traits were detected. No differences were observed in beef tenderness (P = 0.65), and no consistent trends were noted in retail display or palatability data. Less than 20 additional days on feed were required for heifers treated 3 times to have similar BW and carcass characteristics to heifers never treated for BRD. Segregating animals with multiple BRD treatments and feeding them to an acceptable carcass endpoint may be a viable strategy for increasing value of animals treated for BRD.
预期患牛呼吸道疾病（BRD；n = 360；初始 BW = 241.3 +/- 16.6 公斤）风险增加的小母牛在肯塔基州的订单购买设施中进行了组装，并于 2007 年 9 月运往俄克拉荷马州的斯蒂尔沃特，以确定预调理期间观察到的临床 BRD 对随后的育肥性能、胴体特征和肉质属性的影响。在 63 天的预调理期间，BRD 导致的发病率和死亡率分别为 57.6%和 8.6%。预调理后，小母牛根据健康结果进行分组，并分配到育肥栏（每栏 5-7 头）。小母牛从未接受过 BRD 治疗（0X；n = 9 栏），接受过 1 次治疗（1X；n = 9 栏），2 次治疗（2X；n = 6 栏），3 次治疗（3X；n = 6 栏）或被指定为慢性疾病（CI；n = 2 栏）。治疗组之间的初始 BW 没有差异（P = 0.21）。然而，预调理期间疾病发生率降低（P < 0.001），导致 0X、1X、2X、3X 和 CI 组的育肥阶段开始时的 BW 分别为 318、305、294、273 和 243 公斤。在第 65 天和第 122 天通过超声测量的 LM 估计值与 BW 和视觉评估相结合，以针对每个类别和块内的共同平均终点。平均而言，0X、1X 和 2X 组的小母牛在第 163 天屠宰，3X 组在第 182 天屠宰，CI 组在第 189 天屠宰（P < 0.01）。接受 0、1、2 或 3 次治疗的小母牛的最终 BW 相似（P > = 0.18），但被认为是 CI 的小母牛的 BW 比 3X 小母牛的 BW 轻（P = 0.01）。仅考虑育肥阶段，随着 BRD 治疗次数的增加，ADG 呈线性增加（P < 0.001），但随着 BRD 治疗从到达屠宰场的增加而线性下降。因此，CI 的 G:F 高于 3X（P = 0.007），并从 0X 线性增加到 3X（P = 0.002）。与 BW 相似，HCW 比 3X 低（P = 0.03）。大理石花纹评分趋于（P = 0.06）随治疗次数的增加而线性下降，但在胴体性状方面没有发现其他差异（P > = 0.24）。牛肉嫩度没有差异（P = 0.65），零售展示或口感数据也没有发现一致的趋势。对接受 3 次治疗的小母牛来说，只需要多饲养不到 20 天就可以达到与从未接受过 BRD 治疗的小母牛相似的 BW 和胴体特征。对患有多种 BRD 治疗的动物进行分类并将其饲养到可接受的胴体终点可能是增加接受 BRD 治疗的动物价值的可行策略。
