© All Rights Reserved *Corresponding author. Email: drsalah_aal@yahoo.com International Food Research Journal 21(3): 1213-1218 (2014) Journal homepage: http://www.ifrj.upm.edu.my Kamal, R. M., Bayoumi, M. A. and * Abd El Aal, S. F. A. Food control Department, Faculty of Veterinary Medicine, Zagazig University, Egypt Correlation between some direct and indirect tests for screen detection of subclinical mastitis Abstract This study was undertaken to investigate the effectiveness of California mastitis test (CMT), white side test (WST), chlorine test and electrical conductivity (EC) in the diagnosis of subclinical mastitis in dairy cows in a comparison to somatic cell count (SCC) as a standard method for detection of subclinical mastitis. One hundred random samples of cow’s milk were collected from different dairy farms at Dakahlia Governorate, Egypt. SCC revealed that 27% of samples contained less than 2×10 5 SCC/ml. and were considered negative for presence of subclinical mastitis, while mastitic samples (73%) contained higher numbers of SCC exceeded 2×10 5 /ml. CMT results revealed that 27.0% of the examined cow’s milk samples were negative and 73.0% were among the positive samples. The mean values of chlorine % of normal and mastitic cow’s milk samples were 0.093 and 0.157, respectively. EC of normal and mastitic cow’s milk samples revealed that the mean values were 4.08 and 7.42 mS/cm, respectively. Results showed signiicant correlation of these parameters in detection of subclinical mastitis milk samples. Introduction During the last few decades, mastitis has become the most costly disease of dairy cows (Bennett et al., 1999; Fourichon et al., 2001), and it represents a food safety issue. Mastitis causes physical, chemical and bacteriological changes in milk and pathological changes in glandular tissue of udder (Sharma et al., 2007). A primary stage of mastitis, subclinical mastitis, is an inlammation of the mammary gland without noticeable signs, although it is accompanied by 15-45% reduction in daily milk yield and altered milk composition (Swinkels et al., 2005; Halasa et al., 2007). In addition, it is considered a prevailing disease in dairy cows whereas every clinical case of mastitis, 15-40 subclinical cases occur (Kelly et al., 2002). Thus, early diagnosis of mastitis is important for reducing production losses and for enhancing the prospects of recovery. In addition, the identiication of subclinically infected gland is urgently required for successful control of mastitis in dairy animals. While farmers can recognize clinical mastitis, subclinical mastitis can only be discovered by detecting of an inlammatory components and pathogens in the milk (Nielen et al., 1995). Inlammation of mammary gland is directly accompanied by an increase of somatic cell count (SCC) in milk (Rodriguez et al., 2000). Therefore, many reports have considered SCC as a signiicant marker for subclinical mastitis (Dürr et al., 2008). Another test for detection of subclinical mastitis, California Mastitis test (CMT) has been accepted as a quick and simple test to predict SCC from individual quarters or bulk milk. While, an increase in CMT score corresponds to the increase in SCC, it is uncertain whether CMT or SCC scores can accurately relect intramammary infection due to speciic pathogens. Electrical conductivity (EC) is now employed as a routine test for subclinical mastitis detection (Milner et al., 1996). EC is inluenced by sodium, potassium, calcium, magnesium, chlorine and other ions. EC of the milk increases due to an increased concentration of Na + and Cl - . However, factors other than mastitis, like breed, lactation stage, milking interval and milk composition may affect milk EC. Moreover, many dairy producers especially those who still adopt hand milking, may not depend on EC as a routinely test for detection of subclinical mastitis. Due to the aforementioned economic and public health importance, the purpose of the present investigation is directed initially for detection of subclinical mastitis using SCC, CMT, WST, chlorine and EC and to compare the signiicance of each test against the standard SCC. Materials and Methods Samples collection A total of one hundred raw milk samples were Keywords Subclinical mastitis Raw milk Somatic cell count Electrical conductivity Article history Received: 23 November 2013 Received in revised form: 4 January 2014 Accepted: 8 January 2014