Electrical conductivity of milk for detection of mastitis.
ABSTRACT The potential value of electrical conductivity of milk as a screening test for subclinical mastitis was evaluated. Conductivity of foremilk and of postmilking strippings from 368 quarters of 92 cows was measured. Infection status of quarters was determined by bacteriological analysis of strict foremilk samples. Infections were classified as by primary or secondary pathogens, depending on the importance of the isolated organism as a mastitis pathogen. Somatic cells were counted on foremilk samples. Milk conductivity increased with infection. Conductivity of postmilking strippings was higher than that of foremilk in samples from quarters infected by primary pathogens. By thresholds which correctly classified at least 90% of normal quarters, accuracy of identifying primary pathogen infections by absolute conductivity was 62.8 and 96.2% with foremilk and postmilking strippings. Differential conductivity and combination of absolute and differential methods also were evaluated with the latter being the most effective. Number of quarters with elevated conductivity of postmilking strippings tended to be higher when somatic cell count was greater than 500,000/ml in both normal and infected groups. Conductivity of milk seems to hold promise as an indicator of subclinical mastitis.
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ABSTRACT: RESUMEN Se evaluó la medición de la conductividad eléctrica (CE) de la leche en línea y a través de un conductímetro de mano, como método diagnóstico de infecciones intramamarias (IIM). Como patro-nes para definir la clasificación de sano o enfermo se utilizaron: el aislamiento de bacterias patógenas, de patógenos mayores y la conjunción de aislamiento y recuento de células somáticas (RCS) superior a 500.000 células/mL de leche. La medición de la CE como técnica para diagnosticar IIM tuvo mejor desempeño cuando se realizaron mediciones a partir de leche proveniente de cada cuarto mamario. La CE absoluta de la leche en pool se mostró ineficiente para discriminar los casos de IIM, a diferencia de la CE diferencial que requiere la determinación de valores de CE independiente para cada cuarto mamario. Si bien el poder discriminatorio de la CE varía según el criterio de caso de IIM que se utilice, las áreas bajo la curva ROC fueron moderadas cuando se aplicaron a cada cuarto mamario indepen-dientemente, con valores de sensibilidad cercanos al 80%, aunque la tasa de falsos positivos fue de aproximadamente el 50%. Si bien estos valores estimados no fueron muy elevados, la técnica resulta de utilidad para identificar precozmente animales con IIM, siendo una técnica diagnóstica de bajo costo y fácil determinación y resultado inmediato. Palabras claves: conductividad eléctrica, mastitis, diagnóstico, leche. SUMMARY Detection of bovine subclinical mastitis using electric conductivity.Revista FAVE-Ciencias Veterinarias. 01/2009; 8(1):15-28.
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ABSTRACT: The objective of the article was to analyze the influence of psychrotrophic bacteria counts (PBCs) and somatic cell counts (SCCs) on the extent of lipolysis in bulk samples of cow's milk at reception and during cold storage. Samples of milk were analyzed on the day of sampling and subsequently during cold storage. The acidity, fat, density, chloride content, electrical conductivity (EC), bulk milk SCCs (BMSCC), and PBC values were analyzed on the day of sampling and the levels of acidity, EC, SCC, and PBC were analyzed during cold storage at 4 °C for 72 h. The SCC value 869 × 10(3) mL(-1) was higher than the recommended threshold. Lipolysis level at sampling day was related more closely with SCC than with PBC. There was no significant correlation between milk acidity and PBC among others parameters, while the milk mean density was only significant (P < 0.01) correlated with the fat content. The EC and chloride content were consistently correlated (P < 0.001) with BMSCC that allowed them to be used as indicators of mammary gland infection. The milk acidity, EC, PBC, and lipolysis levels increased in relation to the storage time at 4 °C. The lipolysis level during storage was in closer relation to the SCC, but not relation to the PBC. Effects of SCC and PBC on lipolysis decreased throughout the chilling period. It was concluded that initial lipolysis level and intrinsic milk lipoprotein lipase appear more effective than SCC and PBC on the development of lipolysis during storage.Journal of Food Science 08/2013; · 1.78 Impact Factor
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ABSTRACT: The objective of this paper was to evaluate the global milk quality in Tunisian dairy herds. Samples of milk were analyzed for chemical, physical and hygienic parameters. Milk total solids, fat content and density were consistently correlated and one of them can be used as a chemical indicator of milk quality. The somatic cell count value of 689 × 103/mL was higher than the recommended threshold. All milk samples were positive for the major pathogen Staphylococcus aureus. These hygienic parameters were related more closely with chloride content, minerals and electrical conductivity, which allows them to be used as indicators of mammary gland infection. It was concluded that milk producers have at hand rapid and easy tools for assessing the overall quality of milk.Animal Science Journal 05/2014; · 1.04 Impact Factor