Electrical Conductivity of Milk for Detection of Mastitis

Abstract

Milk electrical conductivity is employed for mastitis detection in cows due to its automation, low cost, and infection detectability at early stage. Nevertheless, the number of publications about its use in dairy goats is scarce. The aim of this study was to check and compare the detectability of goat mastitis (sensitivity and specificity) using different algorithms, constructed with individual daily conductivity data from glands, in order to improve the know how about the potential of this variable for goat mastitis detection. A total of 18 goats (8 primiparous and 10 multiparous) free of mastitis were used, and gland milk conductivity was daily monitored. After 16 days of monitoring, some unfavourable situations for gland health were simulated in order to increase the cases of infection. Once infection was established (9 goats and 12 glands got infected), the experiment continued for further 16 days. A total of 19 different algorithms that employed conductivity data from gland were designed; they were tested using gland milk conductivity (EC) and ratio of EC of collateral glands in the same goat (RAT EC). The algorithms were tested in all the animals and intramammary infection detection ability characteristics (sensitivity (SENS), specificity (SPEC), positive predictive value (PPV), and negative pre-dictive value (NPV)) were recorded. All clinical cases were detected (n = 2, 100% SENS) with all the algorithms. Best global SENS (clinical and subclinical, 33.3-58.3%) and SPEC (77.8-100%) were similar to results reported in previous studies in cows, and obtained with algorithms ARIMA and Rule 1 (3 standard deviations of data). The best algorithms to use in mastitis detection depend on the prevalence and type of mastitis. EC ARIMA and Rule 1 algorithms detected the most severe cases on-line and quickly, with a low proportion of false positives.

A Comparison of Mastitis Detection Methods in Dairy Cattle

“…All the three methods thus identify the "healthy" cows with fairly (Table 6). These values were much lower than those reported by GebreEgziabher et al (1979), and Fernando et al (1982) especially for conductivity. Accuracies of over 90Vo were also reported by Linzell and Peaker (1975) …”

Sensitivity and specificity of a hand-held milk electrical conductivity meter compared to the California mastitis test for mastitis in dairy cattle

“…The enumeration of somatic cells is a common method for identification of gland inflammation and is frequently approximated on an ordinal scale using the California milk cell test (CMCT) (Schalm and Noorlander, 1957). Electrical conductivity (or resistance as the inverse) has also been employed to detect mastitis (Fernando et al, 1982;Nielen et al, 1992;Norberg et al, 2004) and hand-held meters have been promoted as a screening tool in South Africa. Milk electrical conductivity is mainly determined by type and concentration of ions, interactive influence of ions, and components contributing to milk viscosity including protein, fat, and lactose (Henningsson et al, 2005).…”

Detection of Abnormal Milk with Impedance Microbiology Instrumentation

“…salt is secreted from the blood to the milk to maintain the same osmolality . Since salt is conductive, but lactose is not , conductivity is applicable to the detection of abnormal milk (10,24).…”

“…Differences in electrical conductivity have been reported when milk was mastitic, as determined with direct current instrumentation (8,10,24,32) . "The objective of this study was to evaluate the ability of this methodology to simultaneously differentiate between milks with different conductivities while measuring the total microflora of raw milk.…”