Background: During subclinical mastitis many changes occur in milk composition such as in mineral concentration which has important role in diagnosis of this disease. In this study, variation of milk chloride, sodium and potassium concentrations was evaluated during different ages of subclinical mastitic river buffalo in Tabriz region, Iran.

Materials and Methods: A total of 580 milk samples were collected with hygienic situation from each quarter of approximately 150 river buffaloes at autumn. The samples were tested using the CMT and bacteriological culture and divided into the different groups according to the culture-positive and culture-negative results and also in age groups (< 3, 3-6 and > 3 years). In all the samples, the concentration of chloride was determined by Ion-selective electrode method and the sodium and potassium concentrations by the flame photometry method.

Results: There was a significant difference between culture-negative and-positive groups concerning all the studied parameters (P<0.05) and the chloride and sodium levels were higher and the potassium lower in the culture-positive group compared with another group, but their levels did not show a significant difference regarding the age groups.

Conclusion: Subclinical mastitis leads to an increase in the levels of chloride and sodium and a decreased potassium concentration in the buffalo milk. Therefore, determination of the aforementioned minerals can have an important role in the evaluation of milk quality and diagnosis of the disease in this species.