Milk electrical conductivity in Manchega ewes: Variation throughout milking and relation with mammary gland health status A., Romero G., Alejandro M., Muelas R., Díaz J.R. (2019): Milk electrical conductivity in Manchega ewes: Variation throughout milking and relation with mammary gland health status. Czech J. Anim. Sci., 64: 300-308.
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The aim of this work was to study the effect of milking fraction and mammary gland health status on the electrical conductivity (EC) of milk from Manchega ewes, considering also the lactation number. To this end, we also studied the relationship of EC with milk macrocomposition, and the relation existing between EC and somatic cell count (SCC). Finally, the use of EC thresholds as a mastitis detection method (sensitivity, specificity, positive (PPV) and negative predictive value (NPV)) was assessed in each of the three fractions: first streams (F1), machine milk (F2) and stripping milk (F3). Milking fraction, mammary gland health status and lactation number had a significant effect on EC and SCC. In the case of EC, the milking fraction caused a more pronounced effect than health status of the glands or number of lactation (F = 19.95, 15.88 and 6.55, respectively; P < 0.5). In SCC, the gland health status caused the most pronounced effect followed by milking fraction and lactation number (F = 112.02, 6.89, and 5.28, respectively; P < 0.05). Changes in the milk composition, especially fat and lactose contents, explained the EC variation to a great extent. For the same EC threshold, specificity and sensitivity varied slightly depending on the milking fraction. NPV above 80% was obtained in the three milking fractions and at all EC thresholds tested, but PPV was only higher than 20% as of the threshold of 4.5, 4.4, and 4.2 mS/cm in F1, F2 and F3, respectively. From the results obtained, we concluded that the algorithm design for mastitis detection in sheep should include those factors affecting the composition and which therefore cause variations in EC, such as milking fraction, individual differences, lactation stage or lactation number.

Albenzio M, Taibi L, Muscio A, Sevi A (2002): Prevalence and etiology of subclinical mastitis in intensively managed flocks and related changes in the yield and quality of ewe milk. Small Ruminant Research, 43, 219-226
Bansal Baljinder K, Hamann Joern, Grabowski Nils Th, Singh Krishan B (2005): Variation in the composition of selected milk fraction samples from healthy and mastitic quarters, and its significance for mastitis diagnosis. Journal of Dairy Research, 72, 144-152
Barkema H.W., Schukken Y.H., Lam T.J.G.M., Galligan D.T., Beiboer M.L., Brand A. (1997): Estimation of Interdependence Among Quarters of the Bovine Udder with Subclinical Mastitis and Implications for Analysis. Journal of Dairy Science, 80, 1592-1599
Bianchi L., Bolla A., Budelli E., Caroli A., Casoli C., Pauselli M., Duranti E. (2004): Effect of Udder Health Status and Lactation Phase on the Characteristics of Sardinian Ewe Milk. Journal of Dairy Science, 87, 2401-2408
M Bruckmaier R., E Ontsouka C., W Blum J. (2012): Fractionized milk composition in dairy cows with&nbsp;subclinical mastitis. Veterinární Medicína, 49, 283-290
Bruckmaier Rupert M, Weiss Daniel, Wiedemann Martin, Schmitz Susanne, Wendl Georg (2004): Changes of physicochemical indicators during mastitis and the effects of milk ejection on their sensitivity. Journal of Dairy Research, 71, 316-321
Caria Maria, Chessa Giovanni, Murgia Lelia, Todde Giuseppe, Pazzona Antonio (2016): Development and test of a portable device to monitor the health status of Sarda breed sheep by the measurement of the milk electrical conductivity. Italian Journal of Animal Science, 15, 275-282
Diaz J.R., Romero G., Muelas R., Sendra E., Pantoja J.C.F., Paredes C. (2011): Analysis of the influence of variation factors on electrical conductivity of milk in Murciano-Granadina goats. Journal of Dairy Science, 94, 3885-3894
Fernando R.S., Spahr S.L., Jaster E.H. (1985): Comparison of Electrical Conductivity of Milk with Other Indirect Methods for Detection of Subclinical Mastitis. Journal of Dairy Science, 68, 449-456
Hamann J., Zecconi A. (1998): Evaluation of the electrical conductivity of milk as a mastitis indicator. Bulletin of the International Dairy Federation, 1998, 334.
Harmon R.J., Eberhart R.J., Jasper D.E., Langlois B.E., Wilson R.A. (1990): Microbiological Procedures for the Diagnosis of Bovine Udder Infection. National Mastitis Council, Arlington, USA.
Leitner G., Chaffer M., Shamay A., Shapiro F., Merin U., Ezra E., Saran A., Silanikove N. (2004): Changes in Milk Composition as Affected by Subclinical Mastitis in Sheep. Journal of Dairy Science, 87, 46-52
Lien C.C., Wan Y.N., Chen H.N. (2005): Performance evaluation of an online EC measurement system for dairy cow mastitis inspection. International Agricultural Engineering Journal, 14, 89–99.
Martí-De Olives Ana, Navarro-Ríos María Jesús, Rubert-Alemán Joaquín, Fernández Nemesio, Molina Maria Pilar (2015): Composition, proteolysis indices and coagulating properties of ewe milk as affected by bulk tank somatic cell count. Journal of Dairy Research, 82, 344-349
McDougall Scott, Murdough Patricia, Pankey Woody, Delaney Carol, Barlow John, Scruton Dan (2001): Relationships among somatic cell count, California mastitis test, impedance and bacteriological status of milk in goats and sheep in early lactation. Small Ruminant Research, 40, 245-254
McKusick B.C., Thomas D.L., Berger Y.M., Marnet P.G. (2002): Effect of Milking Interval on Alveolar Versus Cisternal Milk Accumulation and Milk Production and Composition in Dairy Ewes. Journal of Dairy Science, 85, 2197-2206
Mucchetti Germano, Gatti Monica, Neviani Erasmo (1994): Electrical Conductivity Changes in Milk Caused by Acidification: Determining Factors. Journal of Dairy Science, 77, 940-944
Nielsen N.I., Larsen T., Bjerring M., Ingvartsen K.L. (2005): Quarter Health, Milking Interval, and Sampling Time During Milking Affect the Concentration of Milk Constituents. Journal of Dairy Science, 88, 3186-3200
Peris C., Diaz J.R., Fernandez N., Rodriguez M., Molina P., Torres A. (1998): Employment of electrical conductivity for mastitis detection in sheep. In: Proc. XXIII Scientific Meeting of the Spanish Society of Ovine and Caprine Technology, Ovine and caprine production. Vitoria-Gasteiz, Spain, 381–384. (in Spanish)
Prentice J. H. (1962): The conductivity of milk—the effect of the volume and degree of dispersion of the fat. Journal of Dairy Research, 29, 131-139
Romero G., Pantoja J.C.F., Sendra E., Peris C., Díaz J.R. (2012): Analysis of the electrical conductivity in milking fractions as a mean for detecting and characterizing mastitis in goats. Small Ruminant Research, 107, 157-163
Romero G., Roca A., Alejandro M., Muelas R., Díaz J.R. (2017): Relationship of mammary gland health status and other noninfectious factors with electrical conductivity of milk in Manchega ewes. Journal of Dairy Science, 100, 1555-1567
Santos Rogério A., Mendonça Carla L., Afonso José Augusto B., Simão Luis Carlos V. (2007): Aspectos clínicos e características do leite em ovelhas com mastite induzida experimentalmente com Staphylococcus aureus. Pesquisa Veterinária Brasileira, 27, 6-12
Shuster D.E., Harmon R.J., Jackson J.A., Hemken R.W. (1991): Endotoxin Mastitis in Cows Milked Four Times Daily. Journal of Dairy Science, 74, 1527-1538
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