Risk factors contributing to udder health depression during alpine summer pasturing in Swiss dairy herds.

Summary

One third of Swiss agricultural land is high altitude grassland. 15% of all Swiss dairy cows feed there for about 2 to 5 months during the summer. About 30 % of all alpine bulk milk samples of the Swiss province “Graubünden” exceeded the somatic cell count (SCC) of 350’000/ml. The objective of this project was to evaluate factors effecting increasing SCC on alpine pastures. Foremilk quarter samples of all lactating cows of 3 high-altitude sites (n= 128 cows) were taken once on the 12 farm valley sites (v) and three times during the summer on the alpine sites (a1 to a3). Quarter samples were investigated for microbial pathogens and SCC. Lactation number and lactation days of the cow were recorded. In the statistical models for the three alpine control dates the factors somatic cell count in the valley, infection status in the valley, number of lactation and state of lactation are showing a significant influence on the linear somatic cell score (LSCS). First lactating cows and cows in earlier lactation are showing least square means (LSQ) for LSCS. The same could be found for sterile quarters in the valley and quarters with a low SCC in the valley site. The microbial pathogens which could be found in the valley and in each alp sample are showing a high repeatability of the valley findings. New infections with major pathogens could be avoided. The biggest potential for improving the milk quality in alpine sites lies in the measures to reduce infected cows in the valley sites. It can be recommended to avoid especially the delivery of cows suffering from subclinical mastitis caused by staphyloccus aureus and streptococci to alpine sites.