Bovine respiratory disease (BRD) continues to be great challenge in calf rearing units. The urgent need to decrease the use of antibiotics and increase animal welfare in beef production has forced us to introduce new preventive methods. Vaccinations could contribute to the solution, but the high incidence of BRD already at an early age has made it difficult to introduce suitable vaccination programs. Challenge studies have shown promising results in 3–14 day old calves vaccinated with intranasal BRD vaccine, but very few field trials are available to assess the efficacy of the intranasal vaccines in field conditions. We evaluated the effect of one dose of commercial intranasal vaccination on calf mortality, daily gain, and treatment incidence for BRD in one calf rearing unit. In total, 497 calves (mean age 19 days) were included in our study, 247 of which were vaccinated at the time of arrival to the unit and 250 served as negative controls (unvaccinated). Vaccinated and unvaccinated calves were situated in separate compartments until weaning. Daily gain, treatment incidence, and mortality were recorded until the calves were transported to the finishing unit, which averaged 154.5 days from arrival. Average daily gain over the complete study period was 1151.9 g/day (SD 137.9) for the vaccinated calves and 1139.5 g/day (SD 135.9) for the unvaccinated calves. Intranasal vaccination combined with older arrival age (17 days or older) resulted in a higher daily gain (47.8 g/day) compared with unvaccinated calves (coef. 0.0478, p = 0.003). This association was not recorded in calves that were younger than 17 days upon arrival. Intranasal vaccination was not significantly associated either with mortality (OR 0.976, p = 0.968) or treatment incidence for BRD (OR 1.341, p = 0.120). In total, six vaccinated calves (2.43%) and six unvaccinated calves (2.40%) died during the study period. Vaccinating arriving calves with intranasal vaccine in the calf rearing unit did not decrease the mortality or treatment incidence for BRD, but it significantly improved the weight gain in calves transported to the unit at the age of 17 days or older.

中文翻译：

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野外试验以评估鼻内呼吸疫苗方案对商业犊牛饲养单位中牛呼吸道疾病发病率和生长的影响

牛呼吸疾病（BRD）在小牛饲养单位中仍然是巨大的挑战。减少牛肉生产中抗生素的使用和增加动物福利的迫切需要迫使我们引入了新的预防方法。疫苗接种可能有助于解决该问题，但是BRD在很早的时候就已经很高发病率，因此很难引入合适的疫苗接种计划。挑战研究显示，在鼻腔内接种BRD疫苗的3-14天大牛犊中，前景可观，但很少有田间试验可以评估鼻内疫苗在田间条件下的功效。我们评估了一剂商业鼻内疫苗接种对一头小牛饲养单元中小牛死亡率，日增重和BRD治疗发生率的影响。我们的研究总共包括497个犊牛（平均年龄19天），其中有247人在到达单位时进行了疫苗接种，其中250例用作阴性对照（未接种疫苗）。接种小牛和未接种小牛直至断奶。记录每天的增重，治疗发生率和死亡率，直到小牛被运到育肥单元为止，平均从到达开始到154.5天。在整个研究期间，接种小牛的日平均增重为1151.9克/天（标准差137.9），未接种小牛的日增重为1139.5克/天（标准差135.9）。与未接种疫苗的牛犊相比，鼻内疫苗接种与较大的到达年龄（17天或更大）相结合，导致日增重（47.8 g /天）更高（系数0.0478，p = 0.003）。到达后不到17天的犊牛中未记录到这种关联。鼻内疫苗接种与死亡率（OR 0.976，p = 0.968）或治疗BRD的发生率（OR 1.341，p = 0.120）没有显着相关。在研究期间，总共有六只疫苗接种的小牛（2.43％）和六只未接种疫苗的小牛（2.40％）死亡。在犊牛饲养单元中用鼻内疫苗为到达的犊牛接种疫苗不会降低BRD的死亡率或治疗发生率，但可以显着改善在17天或更年长时运输到该单位的犊牛的体重增加。