Correlations between the number of somatic cells and qualitative and quantitative parameters of milk depending on the stage of lactation of cows from the Bulgarian black and White breed

The study was conducted to establish correlations between the number of somatic cells and quantitative and qualitative parameters in the milk of cows from the Bulgarian Black and White breed. 819 numbers of individual milk samples were tested. The controls were conducted in spring-summer period (April - September) of 2009. The controlled parameters were milk fat (%), total protein (%), somatic cell count (number / ml), milk fat (kg) and milk protein (kg). Distribution in groups: depending on the stage of lactation - up to the 120th day of the lactation (n = 292) and after the 120th day (n = 527) and according to the level of somatic cells in milk- up to 4 somatic cells / ml, from 4 to 5 somatic cells/ml and more than 5 somatic cells/ml. Relationship between the studied parameters is represented by the values of linear correlation. The results show that there are from moderate to high positive correlations between the amount of milk yield per day of quantitative parameters milk fat and milk protein per day for the three levels of somatic cells. Correlation coefficients between the amount of milk yield per day and quality parameters - % milk fat and % of total protein per day for the three levels of somatic cells were negative and moderate. The relationship between the number of somatic cells in milk and quantitative and qualitative parameters is low.