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.
Bibliographical noteFunding Information:
We thank the participating farmers and the teams from SEGES, Registrerings og Ydelseskontrol (RYK; Skejby, Denmark), and Foss Analytical A/S (Hillerød, Denmark) for helping with data acquisition; Silke Hechinger, Karen Schlez, and Tobias Eisenberg at Landesbetrieb Hessisches Landeslabor (Gießen, Germany) for bacterial culture and identification; and Mossa Merhi Reimert (PhD fellow, Copenhagen, Denmark) for graphic consultancy. This project was funded by the Green Development and Demonstration Program (GUDP) under the Danish Directorate for Food, Fisheries and Agriculture (Copenhagen, Denmark), grant no. 34009-15-0918 (EMCo-MAST project). Foss Analytical A/S funded their own participation in this project, including providing SCC and DSCC results. The study design, data collection, sample testing, data analysis, and writing of the manuscript were funded by GUDP. DS is employed by Foss Analytical A/S, the entity manufacturing and selling the Fossomatic 7 DC (among other products), which has been used to produce the DSCC results in this study. MF is employed with SEGES Livestock Innovation (Aarhus, Denmark) and has no conflict of interest. NT is employed with the company IqInABox (Måløv, Denmark) and has no conflict of interest. The other coauthors work at the University of Copenhagen (Frederiksberg, Denmark) and have no conflicts of interest.
- Differential somatic cell count