Relationship between Milk Amyloid A and Haptoglobin concentrations and the electrophoretic pattern of bovine serum milk proteins using SodiumDodecylSulfate Polyacrylamide Gel Electrophoresis (SDSPAGE) in subclinical mastitis caused by common pathogens in Iran

Mastitis is a widely occurring and costly disease in the dairy industry. It remains the most common infectious disease in dairy cattle and the most costly disease affecting the dairy industry.The objective of the present study was to compare the electrophoretic patterns of milk serum proteins from cows with sub-clinical mastitis with healthy cows using SDS-PAGE methodand milk amyloid A (MAA)and Haptoglobin (Hp) concentrations for the diagnosis of bovine subclinical mastitis caused by common pathogensin Iranand alsocomparison between clinical accuracy of MAA, albumin, α- lactalbumin, β-lactoglobulin and Immunoglobulin with determination of somatic cell count in the diagnosis of bovine subclinical mastitis.Milk samples from 59 Holstein cows were randomly selected from five commercial dairy herds in Tehran province, Iran. The milk samples were taken from healthy cows and cows with subclinical mastitis. Milk samples were divided into 2 aliquots; one part was sent to microbiological laboratory for somatic cell count and bacterial culture in the ice bag and the other part was sent to the clinical pathology laboratory Milk serum was isolated and used for electrophoretic and other analytical studies, including MAA, total protein, albumin, α- lactalbumin, β-lactoglobulin and Immunoglobulin measurements.SDS-PAGE method was used for fractionation of serum milk proteins.Milk Amyloid A according at a cut-off point of 0.52 mg/l showed 100% sensitivity and 100% specificity and was regarded as the most accurate method in diagnosis of subclinical mastitis, while determination of the β-lactoglobulin had a little diagnostic value (p = 0.015). On the other hand, comparison between electrophoretic patterns of healthy and mastitic serum milk showed that higher molecular weight bands appeared in the milk of mastitic cows in the range of 70-170KDa, while milks from healthy cows did not show any bands in this range. The results of the present study show thatthe SDS-PAGE method can be a helpful test in diagnosis of subclinical mastitis.