The association between somatic cell count patterns and milk production prior to mastitis

Association between milk yield, milk composition and patterns of peak in Somatic Cell Counts (SCC) were analysed in 4006 Dutch herds with 1 962 752 lactations. Definitions of peak patterns were based on 3 or more consecutive test days, and differentiated between short and long periods of increased SCC. There was a close association between milk yield at start of lactation, without or before SCC-peaks, and the incidence of SCC-peaks. The higher the milk yield, the more likely that SCC-peaks occurred. During peak periods milk-yield dropped, especially for the short intense pattern. Milk yields did not reach pre-peak levels after SCC-peaks. Fat-protein ratios were non-linearly related to SCC-peak rates. Both a lower and a higher fat/protein ratio at the start of lactation increased the risks of SCC-peaks. Across herds there is variation in the association between milk yield and SCC-peaks.