Pritchard D G, Carpenter C A, Morzaria S P, Harkness J W, Richards M S, Brewer J I
Vet Rec. 1981 Jul 4;109(1):5-9. doi: 10.1136/vr.109.1.5.
The effect of a recirculating air filter unit on concentrations of airborne bacteria, clinical and subclinical respiratory disease and production performance of veal calves was studied over a period of one year. Six groups of 28 calves in sheds with internally filtered air were paired by age and time of entry with six similar groups in non-filtered sheds; they were also compared with 23 groups, each of 28 calves, in non-filtered sheds present in the unit during the period of study. Mean aerial bacteria concentration in filtered sheds was reduced by 44.9 per cent (P less than 0.0001). A comparison of unfiltered and filtered sheds on a paired basis showed that the number of animals requiring antibiotic treatment for respiratory disease was reduced by 19.3 per cent (P greater than 0.05). The number of repeat courses of treatment was reduced by 28.9 per cent (P less than 0.025) and total antibiotic usage was reduced by 34.8 per cent (P less than 0.025). At slaughter the average area of lung consolidation in calves from filtered sheds was reduced by 38.4 per cent (P less than 0.025. When all the 644 calves in the unit from 23 non-filtered sheds were compared with the 168 calves in the six filtered sheds the reduction in first treatments, repeat courses and total treatments were 19.7 per cent (P less than 0.025), 28.3 per cent (P less than 0.025) and 31.6 per cent (P less than 0.025) respectively. Air filtration was therefore associated with a reduction in both incidence and severity of clinical and subclinical disease in calves. Both treatment for respiratory disease and area of lung consolidation at slaughter were directly related to reductions in daily weight gain. The economic effect of respiratory disease on veal calves is briefly discussed.
在一年的时间里，研究了循环空气过滤装置对小牛肉牛舍空气中细菌浓度、临床和亚临床呼吸道疾病以及生产性能的影响。在内部空气经过过滤的牛舍中，将6组每组28头小牛按年龄和进入时间与6组在未过滤牛舍中的类似小牛配对；还将它们与研究期间该单位内未过滤牛舍中的23组每组28头小牛进行了比较。过滤牛舍中的平均空气细菌浓度降低了44.9%（P小于0.0001）。成对比较未过滤和过滤牛舍发现，因呼吸道疾病需要抗生素治疗的动物数量减少了19.3%（P大于0.05）。重复治疗疗程的数量减少了28.9%（P小于0.025），抗生素总用量减少了34.8%（P小于0.025）。屠宰时，来自过滤牛舍的小牛肺部实变的平均面积减少了38.4%（P小于0.025）。当将该单位23个未过滤牛舍中的644头小牛与6个过滤牛舍中的168头小牛进行比较时，首次治疗、重复疗程和总治疗次数的减少分别为19.7%（P小于0.025）、28.3%（P小于0.025）和31.6%（P小于0.025）。因此，空气过滤与小牛临床和亚临床疾病的发病率和严重程度降低有关。呼吸道疾病的治疗和屠宰时肺部实变的面积都与日增重的降低直接相关。简要讨论了呼吸道疾病对小牛肉牛的经济影响。
