Potravinarstvo Slovak Journal of Food Sciences Volume 13 562 No. 1/2019 Potravinarstvo Slovak Journal of Food Sciences vol. 13, 2019, no. 1, p. 562-565 https://doi.org/10.5219/1074 Received: 12 March 2019. Accepted: 12 March 2019. Available online: 28 July 2019 at www.potravinarstvo.com © 2019 Potravinarstvo Slovak Journal of Food Sciences, License: CC BY 3.0 ISSN 1337-0960 (online) The electrical conductivity of sheep's milk and the possibility of mastitis detection Michal Uhrinčať, Vladimír Tančin, Kristína Tvarožková, Lucia Mačuhová, Martina Vršková, Martin Ptáček, Ivan Holko 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 × 10 5 , 2 × 10 5 ≤ SCC < 4 × 10 5 , 4 × 10 5 ≤ SCC < 6 × 10 5 , and SCC ≥ 6 × 10 5 cells.mL -1 ), (SCC < 7 × 10 5 and SCC ≥ 7 × 10 5 cells.mL -1 ) and (SCC < 1 × 10 5 and SCC ≥ 1 × 10 5 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 × 10 5 (r = 0.403) and SCC < 2 × 10 5 (r = 0.214). In the second and third classification, we found significant correlations in both cases, the SCC < 7 × 10 5 (r = 0.270) and the SCC ≥ 7 × 10 5 (r = 0.382) and SCC < 1 × 10 5 (r = 0.136) and the SCC ≥ 1 × 10 5 (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 × 10 5 cells.mL -1 . Keywords: electric conductivity; somatic cell count; sheep milk; mastitis INTRODUCTION For sheep farmers it is very important to know the health status of the udder. Increasing SCC leads to a significant reduction in daily milk production, decrease in lactose and a moderate increase in fat and protein (Caria et al., 2016; Tančin et al., 2017; Baranovič et al., 2018) however, it significantly aggravates the coagulation properties of milk (Abdelgawad et al., 2016). Measuring the electrical conductivity (EC) of milk during milking has been studied in cattle as a low-cost mastitis detection method that can be easily automated (Romero et al., 2017). Milk normally has an EC of between 4.0 and 6.0 mS.cm -1 (Ferrero, Valledor and Campo, 2014), but bacterial infection of the udder results in an increase in Na + and Cl - and decreases in the K + levels (Kitchen, 1981), which causes an increase in EC. This is widely used as a method of monitoring mastitis infections. When measured conductivity is in extreme values (6.5 – 13.00 mS.cm -1 ) at 18 °C, this indicates mastitis (Ferrero, Valledor and Campo, 2014). Caria et al. (2016) achieved a sensitivity of 73.08% and a specificity of 75.46% in their study, with an EC threshold of 4.84 mS.cm -1 for sheep milk. There are only a few reports that have been published about the effect of mastitis on the conductivity of sheep's milk. This led us to a decision to evaluate the relationship between 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. Scientific hypothesis The presence of pathogens in sheep milk significantly increases the electrical conductivity of milk. The presence of pathogens in sheep's milk significantly increases SCC in milk. Increasing the number of somatic cells increases the electrical conductivity in milk. There is a moderate positive relationship between SCC and EC.