Rennet-fermentation test is carried out in the milk, taken immediately after the introduction of rennet. Milk in the amount of 20-30 ml are placed in clean sterile tubes, pre-rinsed 2-3 times with the same milk out of the bath. The tubes with the samples placed in an incubator at 37-40 ° C for 12 h, after which they were taken out and assess the quality of milk by the nature of the formed clot. Milk syroprigodnoe and benign on the microflora, coagulates in 20-25 min, and after 12 h produced a uniform, dense clump of cheese, surrounded by a transparent serum. Adding to the normal milk, even 8-12% of mastitic milk retards the development of lactic process causes disorders of coagulation of milk rennet and dramatically reduces the quality of cheese due to the appearance of defects: a bitter, rotten taste and smell of cheese, swelling, flabby clot formation, etc. In addition to the deterioration of the technological properties of milk as raw material for production of cheese, a risk of contamination of milk toksinogennymi staphylococci able to move into the cheese during its elaboration, which may lead to the emergence of poisoning with the consumption of cheese. To eliminate the mastitic milk is necessary to strengthen control on the part of employees of veterinary services and cheese-making plants of the health of dairy cows and putting the company on normal milk. In order to establish the impurity abnormal milk with signs of subclinical mastitis apply the methodology developed by using the drug "mastoprim."