Johnson Kate F, Chancellor Natalie, Burn Charlotte C, Wathes D Claire
Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, UK.
Vet Rec Open. 2017 Nov 28;4(1):e000226. doi: 10.1136/vetreco-2017-000226. eCollection 2017.
Dairy calves are vulnerable to infectious diseases, particularly diarrhoea and bovine respiratory disease (BRD), causing mortality and reducing welfare and growth. A prospective cohort study was performed on 11 UK dairy farms to determine the underlying causes for calf disease. This first paper describes the incidence, timing and duration of infectious disease, mortality rates, passive transfer of immunity and key management practices that may contribute to disease incidence. Heifer calves were recruited in the first week of life (n=492) and a blood sample taken to measure IgG and total protein (TP). Each animal was examined weekly for nine weeks using a standardised health scoring system. Recruitment of calves occurred between August and February. Four farms provided supplementary colostrum to more than 75 per cent of calves born, whereas on the remainder only 0 to 19 per cent were supplemented. Mean serum IgG and TP were 19.0±10 and 56.7±10.3 mg/ml respectively, with 20.7 per cent (95CI: 17.2 to 24.7 per cent) of all calves classified as having failure of passive transfer (IgG <10 mg/ml). The overall preweaning mortality rate was 4.5 per cent. (95 per cent CI: 2.9 to 6.8 per cent). During this period,48.2 per cent of all calves (range 24.1 to 74.4 per cent between farms) were diagnosed with diarrhoea and 45.9 per cent (range 20.4 to 77.8 per cent) with BRD. The incidence rates were 7.8 cases of diarrhoea and 10.1 cases of BRD per 100 calf weeks at risk, respectively. Rates of infectious disease were therefore high despite relatively good passive transfer.
犊牛易患传染病，尤其是腹泻和牛呼吸道疾病（BRD），这些疾病会导致死亡，并降低福利和生长速度。在英国的11个奶牛场进行了一项前瞻性队列研究，以确定犊牛疾病的潜在原因。第一篇论文描述了传染病的发病率、发病时间和持续时间、死亡率、免疫的被动转移以及可能导致疾病发生的关键管理措施。在出生后第一周招募了小母牛犊（n = 492），并采集血样以测量IgG和总蛋白（TP）。使用标准化的健康评分系统，每周对每只动物进行为期九周的检查。犊牛的招募时间为8月至2月。四个农场为超过75%的新生犊牛提供了补充初乳，而在其余农场，只有0%至19%的犊牛得到了补充。血清IgG和TP的平均值分别为19.0±10和56.7±10.3mg/ml，所有犊牛中有20.7%（95%CI：17.2%至24.7%）被归类为被动转移失败（IgG<10mg/ml）。断奶前的总体死亡率为4.5%（95%CI：2.9%至6.8%）。在此期间，所有犊牛中有48.2%（各农场之间的范围为24.1%至74.4%）被诊断出患有腹泻，45.9%（范围为20.4%至77.8%）患有BRD。每100个犊牛周的腹泻发病率为7.8例，BRD发病率为10.1例。因此，尽管被动转移情况相对良好，但传染病的发病率仍然很高。
