Thresholds to determine an IMI at time of calving
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Repeatedly was shown that a cut-off value of approximately 200 000 to 250 000 cells was optimal to distinguish between infected and uninfected quarters in dairy cows (Schukken et al., 2003). However, a cut off value shortly after calving was never established. In this study 258 cows were studied. Quarter milk samples were collected at time of calving. The sensitivity (Se) en specificity (Sp) of SCC at several thresholds were relatively low. Se increased when Sp decreased and vice versa. Milk samples with major pathogens have higher SCC compared with those with minor pathogens isolated. Quarter SCC can be used to give an indication of IMI shortly after calving. The choice of definition of Se and Sp will depend on the objectives of study or control program for which the sample was collected.