Study on the accuracy of milk amyloid A test and other diagnostic methods for identification of milk quality

Bulk tank somatic cell count (BTSCC) is a gold standard test for identification of milk quality, but its results are influenced by several interventional factors. Recently, application of acute phase proteins and especially milk amyloid A (MMA) has been considered as accurate parameters for milk quality study. The current research was done to evaluate the accuracy of MMA, BTSCC, fat, protein and lactose for identification of milk quality. Ninety bulk tank milk samples were collected from 30 randomly selected dairy herds and classified into two groups of samples with BTSSC > 200000 cells per mL and those with BTSSC < 200000 cells per mL. Protein, fat, lactose and MAA contents of samples were analyzed. Average amount of the MAA in healthy and mastitic milk samples were 5.15 and 504.35 ng mL-1, respectively. Statistically significant difference was seen for MAA and total protein contents between two groups. Clinical accuracy of MAA-, total protein-, fat- and lactose–based methods was 0.937, 0.757, 0.665 and 0.547, respectively. The MAA method at concentration of 20.78 ng mL-1 had the highest sensitivity (97.30%) and specificity (46.70%). Evaluation of MAA is recommended as a rapid and accurate method for determination of the unfavorable changes in milk quality and early subclinical mastitis diagnosis.