[Algorithms in the evaluation of electrical conductivity in milk in screening for mastitis]

An algorithm of evaluation of diagnostic data for electronic screening of subclinical and clinical mastitis was derived from 5848 field measurements of the electric conductivity of mammary gland secretions and from the same number of clinical, bacteriological and cytological examinations of 92 dairy cows. The algorithm consists in the calculation of arithmetical mean of the two highest values of mixed, i.e. absolute, and or differential conductivity of a seven-day sliding cycle. Regardless of the intensity of disease forms, for healthy and colonized mammary glands, for mammary glands suffering from nonspecific subclinical mastitis, infectious subclinical mastitis and infectious clinical mastitis, the overall agreement with findings according to repeated clinical, bacteriological and cytological examinations made 88.8% with 4.2% of falsely negative and 7.0% of falsely positive findings. The overall agreement for persistent forms of diseases made 95.3% without falsely negative findings and with 4.7% of falsely positive findings.