Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark.
Foss Analytical A/S, 3400 Hillerød, Denmark.
J Dairy Sci. 2021 Mar;104(3):3427-3438. doi: 10.3168/jds.2020-19378. Epub 2021 Jan 15.
Somatic cell count is frequently used as an indicator of intramammary infections (IMI) in dairy cattle worldwide. The newly introduced differential SCC (DSCC) can potentially contribute to detection of IMI. The purpose of this study was to investigate the dynamics of SCC and DSCC after IMI. We used a data set with monthly samples from 2 Danish dairy herds through 1 yr, using bacterial culture to identify IMI. The dynamics of SCC and DSCC with regard to IMI were assessed at quarter level following new IMI with each of 3 defined pathogen groups, major, minor, or "other" pathogens, using general additive models. Both SCC and DSCC increased after IMI, with a more pronounced increase if major or other pathogens were detected compared with minor pathogens. We found that DSCC increased after IMI with other pathogens in both herds and, in herd 2, after IMI caused by major and minor pathogens. We also estimated the duration of increased SCC and DSCC when they exceeded a threshold, done separately for each pathogen group. Major pathogens had the longest-lasting effect in both herds for both SCC and DSCC. We conclude that the magnitude and duration of response of SCC and DSCC to IMI differs between herds and causative pathogens.
体细胞计数常被用作全世界奶牛乳腺炎（IMI）的指标。新引入的差异 SCC（DSCC）可能有助于检测 IMI。本研究旨在调查 IMI 后 SCC 和 DSCC 的动态变化。我们使用了一个数据集，该数据集包含了丹麦 2 个奶牛场通过 1 年的每月样本，使用细菌培养来识别 IMI。使用广义加性模型，在每个由 3 个定义的病原体组（主要、次要或“其他”病原体）引起的新 IMI 后，在季度水平上评估 SCC 和 DSCC 与 IMI 的动态关系。在 IMI 后，SCC 和 DSCC 均增加，与检测到次要病原体相比，如果检测到主要或其他病原体，则增加更为明显。我们发现，在两个牛群中，其他病原体引起的 IMI 后 DSCC 增加，在牛群 2 中，主要和次要病原体引起的 IMI 后 DSCC 增加。我们还分别估计了每个病原体组的 SCC 和 DSCC 超过阈值时增加的持续时间。主要病原体在两个牛群中对 SCC 和 DSCC 的影响持续时间最长。我们得出结论，SCC 和 DSCC 对 IMI 的反应幅度和持续时间因牛群和病原体而有所不同。
