The electrical conductivity of sheep's milk and the possibility of mastitis detection

Abstract

Measurement of electrical conductivity (EC) is a method frequently used in dairy cows during milking in milking parlours, but especially in robotic milking as a low-cost mastitis detection method. The aim of this study was to evaluate the relationship between somatic cell count (SCC) and EC of milk in sheep reared in Slovakia as factors for monitoring subclinical mastitis on the basis of a bacteriological examination of udder health. Samples were collected individually from both halves of the udder from 295 sheep of different breeds from eight farms during evening milking. Based on SCC, the samples (590) were divided into classes (SCC < 2 × 105, 2 × 105 ≤ SCC < 4 × 105, 4 × 105 ≤ SCC < 6 × 105, and SCC ≥ 6 × 105 cells.mL-1), (SCC < 7 × 105 and SCC ≥ 7 × 105 cells.mL-1) and (SCC < 1 × 105 and SCC ≥ 1 × 105 cells.mL-1) respectively. Based on the presence of pathogens in the udder halve, they were classified as “major pathogens” (14), “minor pathogens” (161) and “without pathogens” (415). The presence of a pathogen had a significant effect on the increase in EC, SCC and protein content and decrease in content of lactose. We found a significant correlation between EV and SCC at first classification only in cases where all data was analysed jointly (r = 0.531), SCC ≥ 6 × 105 (r = 0.403) and SCC < 2 × 105 (r = 0.214). In the second and third classification, we found significant correlations in both cases, the SCC < 7 × 105 (r = 0.270) and the SCC ≥ 7 × 105 (r = 0.382) and SCC < 1 × 105 (r = 0.136) and the SCC ≥ 1 × 105 (r = 0.557). The electrical conductivity showed a stronger correlation with the lactose and protein content than LogSCC. We can argue that measuring the electrical conductivity of sheep milk may be a possible alternative for mastitis detection in sheep. EC can be useful in detecting animals with level of SSC greater than 6 × 105 cells.mL-1.