Nagasawa Yuya, Kiku Yoshio, Sugawara Kazue, Tanabe Fuyuko, Hayashi Tomohito
Dairy Hygiene Unit, Division of Pathology and Pathophysiology, Hokkaido Research Station, National Institute of Animal Health, NARO, Sapporo, Hokkaido, Japan.
Anim Sci J. 2018 Jan;89(1):259-266. doi: 10.1111/asj.12886. Epub 2017 Sep 11.
The exfoliation rate of mammary epithelial cells (MECs) in milk is affected by physiological, breeding and environmental factors. Little is known about the relationship between the MEC exfoliation into milk and mammary-infected Staphylococcus aureus (S. aureus) load on bovine mastitis caused by S. aureus. The aim of this study was to investigate the relationship between S. aureus load and the proportion of MEC exfoliation in milk using five substantial bovine mastitis models. In 64 randomly extracted milk samples from udders at 3-21 days after S. aureus infusion, there were various samples with different numbers of S. aureus counts and somatic cell counts. No significant correlations were found between the S. aureus counts and somatic cell count (r = 0.338). In contrast, a significant correlation was noted between S. aureus counts and the proportion of cytokeratin-positive cells in the milk from the infused udders (r = 0.734, P < 0.01). In conclusion, the increasing MEC exfoliation rate in milk from mastitis udders caused by S. aureus may contribute to reduced milk yield.
牛奶中乳腺上皮细胞（MECs）的脱落率受生理、繁殖和环境因素影响。关于牛奶中MECs脱落与金黄色葡萄球菌（S. aureus）引起的牛乳腺炎中乳腺感染的金黄色葡萄球菌载量之间的关系，人们了解甚少。本研究的目的是使用五个大型牛乳腺炎模型，研究金黄色葡萄球菌载量与牛奶中MECs脱落比例之间的关系。在金黄色葡萄球菌注入后3至21天从乳房随机抽取的64份牛奶样本中，有各种金黄色葡萄球菌计数和体细胞计数不同的样本。金黄色葡萄球菌计数与体细胞计数之间未发现显著相关性（r = 0.338）。相反，在注入乳房的牛奶中，金黄色葡萄球菌计数与细胞角蛋白阳性细胞比例之间存在显著相关性（r = 0.734，P < 0.01）。总之，由金黄色葡萄球菌引起的乳腺炎乳房牛奶中MECs脱落率的增加可能导致产奶量下降。
