Bovine mastitis is a major problem in dairy cattle. Economic losses are mostly associated with decreased production and milk quality, as a consequence of subclinical infections. Staphylococcus aureus is one of the most widely distributed causative agents of subclinical mastitis. For its contagious nature, identification of infected animals is a crucial point in control programs, so that the spread of the infection can be avoided. Currently, the diagnosis of bovine mastitis is mostly based on cyto-bacteriological analysis of milk samples. In the present study differential cell counts were evaluated as an alternative method for mastitis diagnosis. The aims were to identify the DCC variable which is best indicative of udder health, and to evaluate the applicability of the variable in the identification of infected quarters. A new parameter, log PMNL/Lym, was found to best indicate the presence of subclinical mastitis. No influence of parity, lactation stage or quarter position could be found on DCC results. Information on the consistency of this parameter was obtained considering healthy mammary quarters in order to establish test-retest reliability. Sampling day showed no effect on log PMNL/Lym, therefore a cutoff value to identify healthy or diseased quarters could be determined. Such value of 0.495, was then tested under field conditions, showing that best results were obtained combining both DCC and SCC for quarter classification. Sensitivity and specificity were 97.3% and 92.3%, respectively. While somatic cell counting is a worldwide accepted method to identify inflammatory processes in mammary quarters, it provides only limited information, since it evaluates only the total number of milk cells, but not its composition. Differential cell counting, instead, can detect changes in the relative cell populations in milk without rising of total cell numbers, identifying inflammatory processes in quarters otherwise considered as healthy. Such information could be particularly useful when control programs for contagious milk pathogens are being applied. In conclusion, the use of DCC and SCC together could represent an excellent diagnostic method to identify inflammatory processes in the mammary gland, avoiding bacteriological analysis.

DIFFERENTIAL CELL COUNT (DCC) AS AN ALTERNATIVE METHOD TO DIAGNOSE DAIRY COW MASTITIS / R.k. Pilla Silva ; tutor: R. Piccinini ; coordinatore: G. Sironi. UNIVERSITA' DEGLI STUDI DI MILANO, 2013 Feb 05. 25. ciclo, Anno Accademico 2012. [10.13130/pilla-silva-rachel-karine_phd2013-02-05].

DIFFERENTIAL CELL COUNT (DCC) AS AN ALTERNATIVE METHOD TO DIAGNOSE DAIRY COW MASTITIS

R.K. PILLA SILVA
2013

Abstract

Bovine mastitis is a major problem in dairy cattle. Economic losses are mostly associated with decreased production and milk quality, as a consequence of subclinical infections. Staphylococcus aureus is one of the most widely distributed causative agents of subclinical mastitis. For its contagious nature, identification of infected animals is a crucial point in control programs, so that the spread of the infection can be avoided. Currently, the diagnosis of bovine mastitis is mostly based on cyto-bacteriological analysis of milk samples. In the present study differential cell counts were evaluated as an alternative method for mastitis diagnosis. The aims were to identify the DCC variable which is best indicative of udder health, and to evaluate the applicability of the variable in the identification of infected quarters. A new parameter, log PMNL/Lym, was found to best indicate the presence of subclinical mastitis. No influence of parity, lactation stage or quarter position could be found on DCC results. Information on the consistency of this parameter was obtained considering healthy mammary quarters in order to establish test-retest reliability. Sampling day showed no effect on log PMNL/Lym, therefore a cutoff value to identify healthy or diseased quarters could be determined. Such value of 0.495, was then tested under field conditions, showing that best results were obtained combining both DCC and SCC for quarter classification. Sensitivity and specificity were 97.3% and 92.3%, respectively. While somatic cell counting is a worldwide accepted method to identify inflammatory processes in mammary quarters, it provides only limited information, since it evaluates only the total number of milk cells, but not its composition. Differential cell counting, instead, can detect changes in the relative cell populations in milk without rising of total cell numbers, identifying inflammatory processes in quarters otherwise considered as healthy. Such information could be particularly useful when control programs for contagious milk pathogens are being applied. In conclusion, the use of DCC and SCC together could represent an excellent diagnostic method to identify inflammatory processes in the mammary gland, avoiding bacteriological analysis.
5-feb-2013
Settore VET/05 - Malattie Infettive degli Animali Domestici
dairy cow ; differential cell count ; diagnosis ; subclinical mastitis
PICCININI, RENATA
SIRONI, GIUSEPPE
Doctoral Thesis
DIFFERENTIAL CELL COUNT (DCC) AS AN ALTERNATIVE METHOD TO DIAGNOSE DAIRY COW MASTITIS / R.k. Pilla Silva ; tutor: R. Piccinini ; coordinatore: G. Sironi. UNIVERSITA' DEGLI STUDI DI MILANO, 2013 Feb 05. 25. ciclo, Anno Accademico 2012. [10.13130/pilla-silva-rachel-karine_phd2013-02-05].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/216310
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