Use of somatic cell counts for the detection of subclinical mastitis in sheep

Abstract

A study using 100 Chios ewes was undertaken in 1992 to determine rate of clinical mastitis, prevalent bacterial pathogens in normal and abnormal milk and to investigate relationships between somatic cell counts and milk production. Mean somatic cell count from mastitis negative (non-infected) samples was 1.574 × 10 6 cells per ml −1. All mastitis positive samples had somatic cells in excess of 2 × 10 6 cells per ml −1. An increase of 0.5 × 10 6 cells above the mean resulted in reduction of mean individual daily production of milk by 18 g. These findings and the supporting evidence by regression and correlation analyses ( r = −0.33) strongly suggest that the threshold level for subclinical mastitis in ewes should be close to 1.5 × 10 6 somatic cells per ml. The presence of high counts of somatic cells and of pathogens in milk samples, particularly staphylococci, are signs of subclinical mastitis and should trigger prophylactic measures to prevent the outburst of clinical mastitis.