Hägglund S, Hjort M, Graham D A, Ohagen P, Törnquist M, Alenius S
Swedish University of Agricultural Sciences, Department of Clinical Sciences, Division of Ruminant Medicine and Veterinary Epidemiology, P.O. Box 7019, SE-75007 Uppsala, Sweden.
Vet J. 2007 May;173(3):585-93. doi: 10.1016/j.tvjl.2006.02.010. Epub 2006 May 2.
Viral infection dynamics and bovine respiratory disease (BRD) treatment rates were studied over six years at a Swedish bull testing station with an 'all in, all out' management system. In August of each of the years 1998-2003, between 149 and 185 4-8-month-old calves arrived at the station from 99 to 124 different beef-breeding herds, and remained until March the following year. Only calves that tested free from bovine viral diarrhoea virus (BVDV) were allowed to enter the station and original animal groups were kept isolated from new cattle in their original herds for three weeks before admission. Although neither prophylactic antibiotics, nor BRD vaccines were used, less than 0.7-13.2% (mean 5%) of the calves (n=970) required treatment for BRD during the first five weeks following entry. This was probably due, at least in part, to the season (the summer months) when the animals were commingled. In the six-month period August-February, 38% of the animals were treated one or more times for BRD and mortality was 0.7%. Hereford and Aberdeen Angus calves had significantly higher treatment rates than Charolais, Simmental and Blonde d'Aquitaine. Serological testing on samples obtained in August, November and January indicated that bovine parainfluenza virus 3 (PIV-3) infections occurred each year before November after entry. Bovine coronavirus (BCoV) infections also occurred every year, but in 3/6 years this was not until after November. Bovine respiratory syncytial virus (BRSV) infections occurred only every second year and were associated with a treatment peak and one death on one occasion (December). The herd remained BVDV free during the entire study period. The infection patterns for PIV-3 and BCoV indicated a high level of infectivity amongst bovine calves, whereas the incidence for BRSV was observed at a lower level. Although the rearing of the animals differed from conventional beef production, the study has shown that commingling animals from many sources is not necessarily associated with high morbidity within the first few weeks after arrival. By preventing BRD soon after commingling the prerequisites for protective vaccination at entry might be improved. Applied management routines are discussed.
在瑞典一个采用“全进全出”管理系统的公牛测试站，对病毒感染动态和牛呼吸道疾病（BRD）治疗率进行了为期六年的研究。在1998 - 2003年的每年8月，149至185头4至8月龄的犊牛从99至124个不同的肉牛繁殖牛群抵达该站，并一直待到次年3月。只有检测未感染牛病毒性腹泻病毒（BVDV）的犊牛才被允许进入该站，原动物群体在入场前在其原牛群中与新牛隔离三周。尽管未使用预防性抗生素和BRD疫苗，但在入场后的前五周内，只有不到0.7% - 13.2%（平均5%）的犊牛（n = 970）需要接受BRD治疗。这可能至少部分归因于动物混群时的季节（夏季月份）。在8月至2月的六个月期间，38%的动物因BRD接受了一次或多次治疗，死亡率为0.7%。赫里福德和阿伯丁安格斯犊牛的治疗率显著高于夏洛来、西门塔尔和阿基坦 Blonde 犊牛。对8月、11月和1月采集的样本进行的血清学检测表明，牛副流感病毒3型（PIV - 3）感染在每年11月之前入场后都会发生。牛冠状病毒（BCoV）感染每年也会发生，但在6年中有3年直到11月之后才出现。牛呼吸道合胞病毒（BRSV）感染仅每两年发生一次，并且有一次（12月）与治疗高峰和一例死亡相关。在整个研究期间，该牛群一直未感染BVDV。PIV - 3和BCoV的感染模式表明牛犊之间具有高度传染性，而BRSV的发病率较低。尽管动物的饲养方式与传统肉牛生产不同，但该研究表明来自多个来源的动物混群在到达后的最初几周内不一定会导致高发病率。通过在混群后不久预防BRD，可能会改善入场时进行保护性疫苗接种的前提条件。文中还讨论了应用的管理程序。
