A Metrological Contribution to the Diagnosis of Bovine Tuberculosis

The present paper aims to evaluate the actual relevance of the application of metrological criteria for the diagnosis of bovine tuberculosis using Comparative Cervical Tuberculin (CCT) inoculation tests. The present work involves the following steps: identification of the instruments used to measure skin thickness in tuberculin inoculation tests; calibration of the measurement instruments (callipers) using gauge blocks; identification of the variables that can affect the calibration results and the measurement results from inoculation tests; development of a methodology to evaluate the uncertainties associated with both the calliper calibration and with the measurements carried out during diagnosis; mathematical modelling of calliper calibration process and measurement process with the calliper; CCT tests performed in a total of 40 cattle comprising Nellore breed and mixed-breed dairy animals. To determine the effects of uncertainty on the test diagnosis, callipers with resolutions of 0.1 mm and 0.01 mm were compared. The results obtained showed that measurement uncertainty influences the final diagnosis. Therefore, the application of metrological criteria can increase scientific rigor and quality of the results obtained with CCT tests, and consequently, the reliability of the final diagnosis.