Monitoring subclinical intramammary infections on a low bulk milk somatic cell count farm

A detailed study is conducted on a 85 cow herd with a low bulk milk somatic cell count (SCC) to obtain more knowledge on the possibilities to monitor subclinical intramammary infections on well managed dairy farms. During 10 weeks the following data were collected: quarter milk electrical conductivity and whole udder SCC of each milking and twice weekly quarter milk bacteriology and SCC. Prevalence of major pathogens was 5.27 % and prevalence of minor pathogens was 3.35 %. On cow-level, there was a significant relationship between SCC and the prevalence of mastitis pathogens. Only in 48.5 % of the attentions where a cow had an elevated SCC (>250,000 cells/ml), mastitis pathogens could be isolated. For attentions based on electrical conductivity this was 34.8 %. It was interesting that attentions for SCC and electrical conductivity were more complementary than overlapping.