Department of Veterinary Population Medicine, University of Minnesota, Saint Paul 55108, USA.
J Dairy Sci. 2013 Jul;96(7):4419-35. doi: 10.3168/jds.2012-6461. Epub 2013 Apr 28.
The study objective was to compare the efficacy of 3 commercial dry cow mastitis formulations regarding quarter-level prevalence of intramammary infections (IMI) postcalving, cure of preexisting infections over the dry period, prevention of new infections during the dry period, and risk for a clinical mastitis case between calving and 100d in milk (DIM). A total of 1,091 cows (4,364 quarters) from 6 commercial dairy herds in 4 different states (California, Iowa, Minnesota, and Wisconsin) were enrolled and randomized to 1 of the 3 treatments at dry-off: Quartermaster (QT; 1,000,000 IU of procaine penicillin G and 1 g of dihydrostreptomycin; Pfizer Animal Health, New York, NY), Spectramast DC (SP; 500 mg of ceftiofur hydrochloride; Pfizer Animal Health), or ToMorrow Dry Cow (TM; 300mg of cephapirin benzathine; Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO). Quarter milk samples were collected for routine bacteriological culture before dry cow therapy treatment at dry-off, 0 to 6 DIM, and 7 to 13 DIM and an on-farm record-keeping system was used to retrieve data on clinical mastitis cases. Noninferiority analysis was used to evaluate the effect of treatment on the primary outcome, risk for a bacteriological cure during the dry period. Multivariable logistic regression techniques were used to describe the effect of treatment on risk for presence of IMI postcalving and risk of a new IMI during the dry period. Cox proportional hazards regression was used to describe the effect of treatment on the risk and time for quarters to experience an episode of clinical mastitis between calving and 100 DIM. The overall crude quarter-level prevalence of infection at dry-off was 19.2%. The most common pathogen isolated from milk samples at dry-off was coagulase-negative Staphylococcus, followed by Aerococcus spp. and other Streptococcus spp. Noninferiority analysis showed no effect of treatment on risk for a cure between dry-off and calving [least squares means (LSM): QT=93.3%, SP=92.6%, and TM=94.0%] and secondary analysis showed no effect of treatment on risk for presence of an IMI at 0 to 6 DIM (LSM: QT=16.5%, SP=14.1%, and TM=16.0%), risk for development of a new IMI between dry-off and 0 to 6 DIM (LSM: QT=14.8%, SP=12.3%, and TM=14.2%), or risk of experiencing a clinical mastitis event between calving and 100 DIM (LSM: QT=5.3%, SP=3.8%, and TM=4.1%). In conclusion, no difference was observed in efficacy among the 3 products evaluated when assessing the aforementioned quarter-level outcomes.
本研究旨在比较 3 种商业化干奶牛乳腺炎配方制剂在产后 quarters 水平的乳房内感染（intramammary infections，IMI）流行率、干奶期现有感染的治愈率、干奶期新感染的预防以及产后至泌乳 100 天（100 days in milk，DIM）之间发生临床乳腺炎病例的风险。共有 6 个商业奶牛场（加利福尼亚州、爱荷华州、明尼苏达州和威斯康星州）的 1091 头奶牛（4364 个 quarters）参加了这项研究，并在干奶时随机分为 3 种治疗组之一：Quartermaster（QT；100 万 IU 普鲁卡因青霉素 G 和 1 g 二氢链霉素；辉瑞动物保健公司，纽约，NY）、Spectramast DC（SP；500mg 头孢噻呋盐酸盐；辉瑞动物保健公司）或 ToMorrow Dry Cow（TM；300mg 头孢匹林苯甲嗪；Boehringer Ingelheim Vetmedica Inc.，圣约瑟夫，MO）。在干奶治疗前（干奶时）、产后 0 至 6 天（0 至 6 DIM）和产后 7 至 13 天（7 至 13 DIM）采集 quarters 牛奶样本进行常规细菌培养，并使用农场记录系统检索临床乳腺炎病例的数据。非劣效性分析用于评估治疗对主要结局（干奶期内细菌学治愈率）的影响。多变量逻辑回归技术用于描述治疗对产后 quarters 中 IMI 存在风险和干奶期内新 IMI 风险的影响。Cox 比例风险回归用于描述治疗对产后至泌乳 100 天（100 DIM）之间 quarters 发生临床乳腺炎的风险和时间的影响。干奶时 quarters 感染的总体粗患病率为 19.2%。从干奶时的牛奶样本中分离出的最常见病原体是凝固酶阴性葡萄球菌，其次是 Aerococcus spp.和其他链球菌 spp. 非劣效性分析显示治疗对干奶时与产后之间的治愈率风险无影响（最小二乘均值（least squares means，LSM）：QT=93.3%、SP=92.6%和 TM=94.0%），二次分析显示治疗对 0 至 6 DIM 时 IMI 存在风险（LSM：QT=16.5%、SP=14.1%和 TM=16.0%）、干奶时与 0 至 6 DIM 之间新 IMI 发展风险（LSM：QT=14.8%、SP=12.3%和 TM=14.2%）或产后至 100 DIM 之间发生临床乳腺炎事件的风险（LSM：QT=5.3%、SP=3.8%和 TM=4.1%）无影响。总之，在评估上述 quarters 水平结局时，未观察到 3 种评估产品的疗效存在差异。
