Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
J Dairy Sci. 2012 Sep;95(9):4950-4960. doi: 10.3168/jds.2011-5067.
Bovine respiratory disease complex (BRD) is a common disease in weaned dairy calves that incurs economic and welfare costs. This study was an extension of a randomized clinical trial in which a single injection of tulathromycin (TUL) or oxytetracycline (TET) was administered at first movement to group housing for the prevention of BRD in the 60 d following antimicrobial treatment (BRD60). Calves treated with TUL were 0.5 times [95% confidence interval (CI): 0.4 to 0.7] as likely to be treated for BRD60 as calves treated with TET. The objectives of the current study were to evaluate the long-term effects of BRD and antibiotic treatment on growth of heifers until breeding age, age at first calving, incidence of dystocia, milk production, and mortality before first calving and mortality before 120 d in milk. At entry to the breeding barn (382 d of age), calves that experienced BRD60 weighed 16.0±2.3 kg less than calves that did not. Survival to first calving was recorded for 98% (1,343/1,392) of the heifers on this trial. For TET and TUL heifers with BRD60, 63% (94/150) and 73% (64/88) survived to first lactation, respectively. For TET and TUL calves without BRD60, 84% (436/517) and 84% (494/588) survived to first lactation, respectively. The median age at first calving for heifers with and without BRD60 was 714 (95% CI: 705-723) and 702 (95% CI: 699-705) days, respectively. Heifers with BRD60 were 1.5 (95% CI: 1.1-2.2) times more likely to have a calving ease score ≥2 at their first calving compared with heifers without BRD60. The administration of TUL at movement to group housing may have a role in the prevention of BRD and in mitigating some of the long-term effects of this disease.
牛呼吸道疾病复合症（BRD）是断奶奶牛的一种常见病，会带来经济和福利成本。本研究是一项随机临床试验的延伸，该试验在首次移动到群体饲养时，对牛只注射了单剂量的泰乐菌素（TUL）或土霉素（TET），以预防抗菌治疗后 60 天（BRD60）的 BRD。与 TET 治疗的牛只相比，接受 TUL 治疗的牛只因 BRD60 接受治疗的可能性低 0.5 倍[95%置信区间（CI）：0.4 至 0.7]。本研究的目的是评估 BRD 和抗生素治疗对育成牛直到配种年龄、首次产犊年龄、难产发生率、产奶量以及首次产犊前和首次产犊后 120 天内的死亡率的长期影响。在进入繁殖畜舍时（382 日龄），经历 BRD60 的牛只比未经历 BRD60 的牛只体重轻 16.0±2.3 公斤。本试验记录了 98%（1343/1392）的育成牛只的首次产犊存活率。对于 TET 和 TUL 治疗的患有 BRD60 的牛只，63%（94/150）和 73%（64/88）的牛只存活到第一次泌乳，分别。对于 TET 和 TUL 治疗的未患 BRD60 的牛只，84%（436/517）和 84%（494/588）的牛只存活到第一次泌乳，分别。患有和不患有 BRD60 的牛只的首次产犊中位年龄分别为 714（95%CI：705-723）和 702（95%CI：699-705）天。患有 BRD60 的牛只在首次产犊时的产犊舒适度评分≥2 的可能性是不患有 BRD60 的牛只的 1.5 倍[95%CI：1.1-2.2]。在移动到群体饲养时给予 TUL 可能在预防 BRD 以及减轻这种疾病的一些长期影响方面发挥作用。
