Shuster D E, Harmon R J, Jackson J A, Hemken R W
Department of Animal Sciences, University of Kentucky, Lexington 40546-0215.
J Dairy Sci. 1991 May;74(5):1527-38. doi: 10.3168/jds.S0022-0302(91)78313-6.
As part of a project to identify the pathophysiological cause or causes of mastitic hypogalactia, midlactation cows were infused in two homolateral quarters with 10 micrograms of endotoxin while being milked four times daily to resolve better the temporal changes in mammary synthetic activity during endotoxin mastitis. Milk fat was decreased by the first milking (5 h) postinfusion and then recovered rapidly. In contrast, milk yield and the yields of protein and lactose were not significantly inhibited until the second milking, and these yields recovered slowly thereafter. The decline in milk yield by infused quarters was only 20% greater than the decline by uninfused quarters in this experiment. Mammary inflammation developed rapidly in infused quarters as milk serum albumin concentration was maximal at the first milking. Milk SCC and NAGase were also elevated at this time, and maximal levels occurred at milkings 2 to 4. Increased temperature, increased cortisol, and a mild anorexia were apparent at the first milking only. Endotoxin treatment had no effect on serum prolactin or glucose. These data suggest that the delayed hypogalactia is consequent to the mammary inflammation and systemic responses following endotoxin infusion. The results indicate that different pathophysiological events may inhibit synthesis of the different milk components.
作为确定乳腺炎导致泌乳减少病理生理原因项目的一部分，对处于泌乳中期的奶牛两个同侧乳腺区注入10微克内毒素，同时每天挤奶4次，以便更好地解析内毒素性乳腺炎期间乳腺合成活性的时间变化。注入内毒素后首次挤奶（5小时）时乳脂下降，随后迅速恢复。相比之下，产奶量以及蛋白质和乳糖产量直到第二次挤奶时才受到显著抑制，且此后恢复缓慢。在本试验中，注入内毒素乳腺区的产奶量下降幅度仅比未注入内毒素乳腺区大20%。注入内毒素的乳腺区迅速出现乳腺炎症，因为首次挤奶时乳清白蛋白浓度最高。此时乳中体细胞计数和N - 乙酰 - β - 氨基葡萄糖苷酶也升高，且在第2至4次挤奶时达到最高水平。仅在首次挤奶时出现体温升高、皮质醇增加和轻度食欲不振。内毒素处理对血清催乳素或葡萄糖没有影响。这些数据表明，泌乳减少延迟是内毒素注入后乳腺炎症和全身反应的结果。结果表明，不同的病理生理事件可能抑制不同乳成分的合成。
