Waage S, Sviland S, Odegaard S A
National Veterinary Institute, Oslo, Norway.
J Dairy Sci. 1998 May;81(5):1275-84. doi: 10.3168/jds.S0022-0302(98)75689-9.
A nested case-control study was conducted to identify risk factors for clinical mastitis in heifers. Cases and controls originated from dairy herds that were enrolled in the Production Recording Scheme. Heifers that had been treated for clinical mastitis prepartum or on the day of parturition were eligible for inclusion as cases. The controls were heifers that had not been treated for clinical mastitis before parturition, during their first lactation, or during the dry period. In the final analysis, 4256 heifers with mastitis and 67,072 control heifers were included. An increase in the incidence of clinical mastitis in the herd, a decrease in the bulk milk somatic cell count, and an increase in the mean milk yield of the herd were associated with an increased risk for clinical mastitis. The risk varied among regions, and, depending on region, significant influences of both herd size and composition of the diet were observed. Heifers kept on pasture in summer were at a decreased risk for clinical mastitis. Calving in late spring or summer was associated with greater risk than was calving at other times of the year. An increase in age at first calving was associated with increased risk of mastitis. Mastitis was also more likely to occur in heifers leaking milk or in heifers that had a low milk flow rate in the subsequent lactation. For purchased heifers, risk factors were identified in both their previous and current herds.
开展了一项巢式病例对照研究，以确定小母牛临床乳腺炎的风险因素。病例和对照均来自参与生产记录计划的奶牛场。产前或分娩当天接受过临床乳腺炎治疗的小母牛有资格纳入病例组。对照组为在分娩前、第一个泌乳期或干奶期未接受过临床乳腺炎治疗的小母牛。最终分析纳入了4256头患乳腺炎的小母牛和67072头对照小母牛。牛群中临床乳腺炎发病率的增加、批量牛奶体细胞计数的减少以及牛群平均产奶量的增加与临床乳腺炎风险的增加相关。风险因地区而异，并且根据地区不同，观察到牛群规模和日粮组成均有显著影响。夏季在牧场饲养的小母牛患临床乳腺炎的风险降低。春末或夏季产犊比一年中其他时间产犊的风险更大。首次产犊年龄的增加与乳腺炎风险的增加相关。乳腺炎也更有可能发生在漏奶的小母牛或随后泌乳期奶流率低的小母牛身上。对于购买的小母牛，在其之前和当前的牛群中均确定了风险因素。
