To assess the exactness of the tests, the predictive values
and likelihood ratios were calculated. A positive predictive
value indicates the proportions of animals with a positive
test which are really diseased, whereas, the likelihood ratio
of a positive test result expresses how much more likely the
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Zinc concentration in subclinical mastitis buffalo milk (ppm)
Alkalineanimal is to have a positive test result when actually diseased than if disease free (i.e. it is the ratio of the likelihoods of having and not having the disease). Likelihood test of a positive test result >10 indicates that the test can be used to rule in the disease. A likelihood ratio of a negative result describes how much more likely the animal is used to have a negative test result if it has the disease than if it is a disease free (Petrie and Watson, 2008). The likelihood ratio of positive test for all kinds of infections (Table 4) amongst all the parameters was higher for ALP followed by Zn (above 10 for both). The likelihood ratio of positive test for rest of the parameters was below 10, indicating that they were not reliable to diagnose SCM. For Gram positive infections the value was greater than 10 for all the parameters (Table 5). For ALP and LDH the values were comparable with the observations of Gera and Guha (2011b) in cow milk, suggesting ALP as the indicator of SCM in crossbred cattle.