Screening method for early detection of mastitis in cows F.J. Ferrero ⇑ , M. Valledor, J.C. Campo Department of Electrical and Electronic Engineering, University of Oviedo, Spain article info Article history: Received 1 July 2013 Received in revised form 10 September 2013 Accepted 4 October 2013 Available online 17 October 2013 Keywords: Electrical conductivity Milk quality Mastitis Wheatstone bridge abstract Mastitis in cows is an inflammation of the mammary gland usually caused by bacterial infection of udder tissues. This disease causes considerable damages to the cattlemen when reducing the quantity and the quality of the produced milk. An early detection and correc- tive action can lead to early cure. Although the universal method to measure mastitis levels is by determining the somatic cell counts per milliliter of milk, the electrical conductivity of milk could be a rapid test for checking the acceptability of milk to monitor the effects of udder infection. In this paper a low-cost circuit for estimating the quality of raw milk based on AC electrical conductivity measurements is proposed. It consists in the use of a modified Wheatstone bridge to minimize the parasitic effects. A conductivity cell consisting of two electrodes and a coaxial cable was also designed. The temperature of the milk is also mea- sured and compensated its effect. This system can help the farmer to detect quickly and economically the state of health of their cows from a simple measurement of electrical con- ductivity performed on the dairy farm itself. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Mastitis in cows is an inflammation of the mammary gland and is usually caused by bacteria infection of the ud- der tissues. It is the most costly disease on the dairy farm today. According the statistical information total losses for the United States are in the range of 1.5–3 billion USD annually, or 11% of the total USA milk production. Mastitis can be clinical or sub-clinical. Clinical mastitis gives abnor- mal milk and swelling of the udder. Bacteria are present in the milk, and the composition of the milk is dramatically changed. Sub-clinical mastitis is more problematic because no visible changes appear in the milk or the udder, but milk production decreases, bacteria are in the milk, and the composition is altered. Mastitis has a very negative ef- fect on product quality, due to increased enzymatic activ- ity. This effect will reduce cheese yield, butter yield, change acid production in fermented products and lead to taste defects in all kinds of dairy products. To encourage farmers to lower the level of mastitis, many dairies offer premium payment programs for milk free of mastitis and reduction in payment for milk with high mastitis level. A complete review about mastitis detection, current trends and future perspectives in presented in [1]. Different methods are used to assess milk quality. Some methods such us somatic cell count (SCC) are mandated. Other methods, while not mandated, are used to monitor milk quality and help diagnose potential on-farm problems associated with abnormally high counts and poor quality milk. One of these methods is the use of the electric con- ductivity of milk (ECM) [2–4]. Milk normally has an EC of between 4.0 and 6.0 mS/cm. However, milk from a cow af- fected by mastitis is a better conductor of electric current than that from a healthy cow due to increased Na + and Cl  ions and the reduction in the content of K + ions and lac- tose [5]. Therefore, measurement of conductivity can therefore help in the early identification of mastitis. There is a strong relation between the electrical con- ductivity of the foremilk and its lactose and salt content. Illness not related to the udder, problems in metabolism, changes in the diet, breed, stress and the stage of lactation influence the conductivity whilst having a lesser influence on somatic cell count. Studies of milk electrical properties 0263-2241/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.measurement.2013.10.015 ⇑ Corresponding author. Tel.: +34 985182552; fax: +34 985182138. E-mail address: ferrero@uniovi.es (F.J. Ferrero). Measurement 47 (2014) 855–860 Contents lists available at ScienceDirect Measurement journal homepage: www.elsevier.com/locate/measurement