Diagnostic Value of Milk Enzymatic Markers Lactate Dehydrogenase and Alkaline Phosphatase for Subclinical Mastitis in Dairy Cattle

Mastitis could be diagnosed by diverse methods, including physical, clinical, and laboratory tests. The present study aimed to evaluate the accuracy of subclinical mastitis diagnosis using enzymatic diagnostic tests for milk lactate dehydrogenase (LDH) and alkaline phosphatase (ALP). This study was performed on 90 Holstein cows selected randomly out of high- and low-yielding dairy cattle. According to the result of the California Mastitis Test, two milk samples were obtained from the intended udder quarters based on the principles of the National Mastitis Council. One specimen was used for microbial culture and the other one was utilized for somatic cell count (SCC), as well as milk LDH and ALP tests by diagnostic kits. Considering microbial culture as the gold standard for subclinical mastitis diagnosis, the sensitivity of SCC, ALP, and LDH tests was 87%, 59.3%, and 70.4%, respectively. Moreover, the specificity of these tests was 77.8%, 80.6%, and 77.8%, respectively. Our findings revealed a strong correlation between SCC, LDH, and ALP. It was observed that an increase in SCC was accompanied by augmented LDH response. According to the results of the present study, SCC was the most efficient test for diagnosing subclinical mastitis in dairy cows, followed by LDH and ALP.