Morse D, DeLorenzo M A, Wilcox C J, Collier R J, Natzke R P, Bray D R
Dairy Science Department, University of Florida, Gainesville 32611.
J Dairy Sci. 1988 Mar;71(3):848-53. doi: 10.3168/jds.S0022-0302(88)79626-5.
Clinical mastitis records for 6.5 yr from a large north Florida dairy and corresponding daily weather data were analyzed. Monthly incidence of clinical mastitis was expressed as percent of cow-days in milk and graphed against monthly average daily maximum temperature humidity index values and monthly total rainfall. No trends were evident with rainfall. In 3 of 6 yr, monthly incidence of clinical mastitis increased more than 50% above annual incidence, and this followed high monthly temperature-humidity values. Least squares was used to estimate regression coefficients of temperature-humidity index categories based on 999,969 Holstein records. A temperature humidity index category represented the number of days used to calculate average daily maximum temperature-humidity index value. Sources of variation in observed occurrence of clinical mastitis were cow, parity, month, year, interaction of parity by month, and continuous effects of temperature-humidity index categories 2, 6, 15, 30, 60, each to third order and 60 by parity interaction. In all temperature-humidity index categories as the temperature-humidity index value increased, occurrence of clinical mastitis increased. When values rose from 55 to 80, twice as many for 2 d cows showed signs of clinical mastitis.
分析了佛罗里达州北部一家大型奶牛场6.5年的临床乳腺炎记录以及相应的每日天气数据。临床乳腺炎的月度发病率以产奶牛天数的百分比表示，并与月平均每日最高温度湿度指数值和月总降雨量进行了绘图。降雨量方面没有明显趋势。在6年中的3年里，临床乳腺炎的月度发病率比年发病率高出50%以上，且这发生在月度温度湿度值较高之后。基于999,969条荷斯坦奶牛记录，使用最小二乘法估计温度湿度指数类别的回归系数。一个温度湿度指数类别代表用于计算平均每日最高温度湿度指数值的天数。观察到的临床乳腺炎发生情况的变异来源包括奶牛、胎次、月份、年份、胎次与月份的交互作用，以及温度湿度指数类别2、6、15、30、60的连续效应，每个效应到三阶以及60与胎次的交互作用。在所有温度湿度指数类别中，随着温度湿度指数值的增加，临床乳腺炎的发生率增加。当值从55上升到80时，2胎奶牛出现临床乳腺炎症状的数量增加了一倍。
