Schneider M J, Tait R G, Busby W D, Reecy J M
Department of Animal Science, Iowa State University, Ames 50011, USA.
J Anim Sci. 2009 May;87(5):1821-7. doi: 10.2527/jas.2008-1283. Epub 2009 Jan 30.
The objective of this study was to investigate the effects of bovine respiratory disease (BRD) complex on economically important production traits with the use of health records in combination with lung lesion scores obtained at slaughter. Records from 5,976 animals were used in this study from cattle that were managed in Midwestern feedlots. Average daily gain for 3 different feeding periods (acclimation, on-test, and overall test) along with final BW were evaluated as performance measures. Hot carcass weight, LM area, subcutaneous fat cover, and marbling score were collected at slaughter. All calves were monitored by experienced feedlot personnel and treated according to the specific health protocol of each feedlot. Incidence of BRD was observed at a rate of 8.17%, and lung lesions at slaughter were present in 61.9% of cattle from a subpopulation (n = 1,665). From this group of cattle, the overall incidence of BRD, which was defined as cattle that had lung lesions, that were treated for BRD in the feedlot, or both, was 64.4%. Incidence of BRD in the feedlot decreased ADG during both the acclimation period (0.37 +/- 0.03 kg) and the overall test period (0.07 +/- 0.01 kg). Incidence of BRD also had significant effects on HCW and marbling score with reduction of 8.16 +/- 1.38 kg and 0.13 +/- 0.04, respectively, in treated cattle. The adverse effects on production traits tended to increase as the number of treatments increased. Potential decrease in performance and carcass merit observed in this study were associated with a decline of $23.23, $30.15, and $54.01 in carcass value when comparing cattle never treated with cattle treated once, twice, or 3 or more times, respectively. The presence of lung lesions did not have a significant effect on any of the traits; however, there was an association between the presence of active bronchial lymph nodes and less productivity of feedlot cattle.
本研究的目的是利用健康记录并结合屠宰时获得的肺部病变评分，调查牛呼吸道疾病（BRD）综合征对重要经济生产性状的影响。本研究使用了来自中西部饲养场的5976头牛的记录。评估了3个不同饲养阶段（适应期、试验期和整个试验期）的平均日增重以及最终体重作为生产性能指标。屠宰时收集了热胴体重、腰大肌面积、皮下脂肪厚度和大理石花纹评分。所有犊牛均由经验丰富的饲养场工作人员进行监测，并根据每个饲养场的特定健康方案进行处理。观察到BRD的发病率为8.17%，在一个亚群（n = 1665）中，61.9%的牛在屠宰时有肺部病变。在这群牛中，BRD的总体发病率（定义为有肺部病变、在饲养场接受过BRD治疗或两者皆有的牛）为64.4%。饲养场中BRD的发病率在适应期（0.37±0.03千克）和整个试验期（0.07±0.01千克）均降低了平均日增重。BRD的发病率对热胴体重和大理石花纹评分也有显著影响，治疗牛的热胴体重和大理石花纹评分分别降低了8.16±1.38千克和0.13±0.04。随着治疗次数的增加，对生产性状的不利影响趋于增加。在本研究中观察到的生产性能和胴体品质的潜在下降与从未接受治疗的牛与分别接受过一次、两次或三次及以上治疗的牛相比，胴体价值分别下降23.23美元、30.15美元和54.01美元有关。肺部病变的存在对任何性状均无显著影响；然而，活跃支气管淋巴结的存在与饲养场牛的生产力较低之间存在关联。
