DeHart D A, Natzke R P, Oltenacu P A
J Dairy Sci. 1976 Jun;59(6):1124-30. doi: 10.3168/jds.S0022-0302(76)84332-9.
This project was designed to study rates of infection in udders of cows exposed to an Escherichia coli broth culture at milking time. Forty Holstein cows of varied stages of lactation were divided randomly into three treatment and one control group of ten cows each. The treatment groups were exposed for 3 wk to an Escherichia coli broth of 10(9) colony forming units per ml at milking time by either 1) dipping teat ends in broth before milking, 2) spraying the udder and leaving it dripping wet during milking, or 3) dipping teat ends in broth after milking. Eleven of 30 treated cows became infected in one or more quarters; all control cows remained uninfected. The infection rate of the three Escherichia coli-treated groups was higher than the controls. However, there was no difference among treated groups. Exposure to the broth culture of Escherichia coli increased the infection rate, but the time at which the udder was exposed to the organisms was unimportant. All infections were of the same type with the same O and H group antigens as the Escherichia coli broth.
本项目旨在研究在挤奶时接触大肠杆菌肉汤培养物的奶牛乳房感染率。40头处于不同泌乳阶段的荷斯坦奶牛被随机分为三个处理组和一个对照组，每组10头奶牛。在挤奶时，处理组奶牛通过以下方式之一接触每毫升含10(9)个菌落形成单位的大肠杆菌肉汤3周：1)挤奶前将乳头末端浸于肉汤中；2)挤奶时对乳房进行喷雾并使其保持滴水状态；3)挤奶后将乳头末端浸于肉汤中。30头接受处理的奶牛中有11头在一个或多个乳腺中发生感染；所有对照奶牛均未感染。三个大肠杆菌处理组的感染率高于对照组。然而，各处理组之间没有差异。接触大肠杆菌肉汤培养物会增加感染率，但乳房接触该微生物的时间并不重要。所有感染均为与大肠杆菌肉汤具有相同O和H组抗原的同一类型。
