Daros Rolnei R, Hötzel Maria J, Bran Jose A, LeBlanc Stephen J, von Keyserlingk Marina A G
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, Canada.
Laboratório de Etologia Aplicada e Bem-Estar Animal, Departamento de Zootecnia e Desenvolvimento Rural, Universidade Federal de Santa Catarina, Florianópolis, Brazil.
Prev Vet Med. 2017 Sep 15;145:16-22. doi: 10.1016/j.prevetmed.2017.06.004. Epub 2017 Jun 9.
The aim of this cross-sectional study was to describe the incidence risk of dystocia, retained placenta (RP), pathological recumbence (down cow), the prevalence of metritis and subclinical ketosis (SCK), and the risk factors for SCK, metritis, and RP in grazing dairy herds in Southern Brazil. Fifty-three herds were visited 2-6 times from February to October of 2015. Body condition score (BCS), breed, days in milk (DIM), parity and disease status were recorded for each cow that was between 3 and 21 DIM at the time of the visits. Management practices were determined using a survey and environmental inspection was performed on each visit. SCK was identified if blood β-hydroxybutyrate was ≥1.2mmol/L and metritis by inspection of the vaginal discharge; cows were assessed once between 3 and 21 DIM. Multilevel logistic regression models, controlling for farm as a random effect, were built to identify risk factors for each disease and to assess the proportion of variance at the herd and cow levels. Models were constructed based on causal diagrams and variable screening. Overall, prevalence of SCK and metritis and incidence risk of RP were 21, 11 and 14%, respectively. Reported incidence risk of down cow was 6% and displaced abomasum was 1%. The odds (OR; 95% CI) of a cow having SCK were higher in herds with high (>10%) incidence of down cows (2.7; 1.4-5.0), limited access to water (1.9; 1.1-3.1), Jersey cows (OR: 2.2; 1.2-4.1) and in cows that were in third or greater lactation (2.9; 1.4-5.5). BCS 3.0-3.5 decreased the odds (0.4; 0.2-0.8) of metritis, while DIM, RP and being in a herd with a dirty holding area increased the odds of metritis by 1.1 (1.1-1.2), 19.5 (9.9-38.3) and 2.1 (1.0-4.2) fold, respectively. Parity >2 and dystocia increased the odds of RP by 2.4 (1.2-4.6) and 3.0 (1.6-5.4) fold, respectively. Jersey breed, use of a maternity pen and keeping the newborn calf with the cow >12h decreased the odds of having RP by 0.1 (0.0-0.4), 0.5 (0.3-1.0) and 0.4 (0.2-0.8) times, respectively. The variation in disease occurrence was largely dependent on cow-level factors. However, herd level risk factors also influenced disease occurrence and should be considered in order to design better preventive transition period diseases protocols.
这项横断面研究的目的是描述巴西南部放牧奶牛群中难产、胎盘滞留（RP）、病理性躺卧（倒地不起母牛）的发病风险，子宫内膜炎和亚临床酮病（SCK）的患病率，以及SCK、子宫内膜炎和RP的风险因素。2015年2月至10月期间，对53个牛群进行了2至6次走访。记录每次走访时处于产奶3至21天的每头奶牛的体况评分（BCS）、品种、产奶天数（DIM）、胎次和疾病状况。通过调查确定管理措施，并在每次走访时进行环境检查。若血液β-羟丁酸≥1.2mmol/L则判定为SCK，通过检查阴道分泌物判定是否为子宫内膜炎；在产奶3至21天之间对奶牛进行一次评估。建立了以农场为随机效应的多水平逻辑回归模型，以确定每种疾病的风险因素，并评估牛群和奶牛水平的方差比例。模型基于因果图和变量筛选构建。总体而言，SCK和子宫内膜炎的患病率以及RP的发病风险分别为21%、11%和14%。报告的倒地不起母牛的发病风险为6%，皱胃移位为1%。在倒地不起母牛发病率高（>10%）的牛群中，奶牛患SCK的几率（比值比；95%置信区间）更高（2.7；1.4 - 5.0），饮水受限（1.9；1.1 - 3.1）、泽西牛品种（比值比：2.2；1.2 - 4.1）以及处于第三胎或更高胎次的奶牛（2.9；1.4 - 5.5）也是如此。BCS为3.0 - 3.5可降低子宫内膜炎的几率（0.4；0.2 - 0.8），而产奶天数、胎盘滞留以及处于牛舍肮脏区域的牛群会使子宫内膜炎的几率分别增加1.1（1.1 - 1.2）倍、19.5（9.9 - 38.3）倍和2.1（1.0 - 4.2）倍。胎次>2和难产分别使胎盘滞留的几率增加2.4（1.2 - 4.6）倍和3.0（1.6 - 5.4）倍。泽西牛品种、使用产房以及让新生犊牛与母牛在一起超过12小时分别使发生胎盘滞留的几率降低0.1（0.0 - 0.4）倍、0.5（0.3 - 1.0）倍和0.4（0.2 - 0.8）倍。疾病发生的差异在很大程度上取决于奶牛水平的因素。然而，牛群水平的风险因素也会影响疾病发生，为了设计更好的围产期疾病预防方案，应该予以考虑。
