Somatic cells of raw milk – blood cells, white blood cells, red blood cells, epithelial cells, which zluschylysya from the alveoli and milk duct of mammary gland. According to different authors number of somatic cells in raw cow milk ranges from 60-80 thousand/cm³ to 1 million/cm³, depending on the condition of the udder. In the presence of inflammation (mastitis) in the mammary gland number of leukocytes increases to ten millions due to their enhanced migration in inflammation. Accordingly the total number of somatic cells in milk increases.

At the initial stage of inflammation destructive processes in the mammary gland do not cover substantially the biosynthesis of milk proteins. The content of total protein remains unchanged, but there are significant changes in the structure of the alveolar epithelium, as indicated by the change in the number of glycoproteins, primarily due to degradation products of hyaluronic acid, which is a matrix for binding of the epithelial cells of the alveoli. The increase of  immunoglobulins concentration is marked, in their structure, probably there are certain changes that are caused by a decrease in the content of N-acetylneuraminic acid that is the link between protein globules and carbohydrate hapten in each immunoglobulin.

Research was conducted on cows of black and white breeds that are kept in NNDTS of BNAU. Samples of milk from each cow were collected by automatic selector milk or by probe under the proportional yield of ISO 707:2002. Research of milk samples was performed in the research laboratory of veterinary-sanitary examination and hygiene of livestock products of BNAU. The number of somatic cells in milk were determined by direct counting of somatic cells on analyzer "EkomilkScan”, made in the USA, working on the principle of laser-fluorescence flow cytometry. The level of sialic acids was determined by the method of Hess, qualitative indices of milk – by standardized methods.

As a result of our research number of somatic cells in the tested samples ranged from 90 to 1,500 thousand/сm³, and averaged 455,0±156,27 thousand/сm³, that corresponded to the first grade.

In the cow’s milk from the first group (20%) the number of somatic cells ranged from 1170 to 1,500thousand /сm³, which is typical of subclinical mastitis. In the cow’s milk from the second group (10%) – the number of somatic cells ranged from 583 to 600 thousand/сm³, which meets the requirements for the first grade milk, in the cow’s milk from the third group (70%) - indices ranged from 90 to 360 thousand/cm³, typical for extra and the highest quality milk.

According to literary sources 5% cows from the herd identify 50% of the total content of somatic cells of milk per herd, in our case there were 20% animals. According to GOST 3662-97 (with changes) in milk class "extra" and "higher" the number of somatic cells should not exceed   400 thousand/cm³, the "first" – 600 thousand/cm³ and "second" - 800 thousand/cm³.

Increased somatic cell 500 thous. /сm³ may be indicative of subclinical and 1 million / cm³ – the clinical form of its manifestation. According to other authors, content of somatic cells in milk between 200 thousand/cm³, and in some cases 100 thousand./сm³ can be a sign of disease.

Inflammation of the tissues of the udder may be expressed by clinical signs and hidden (subclinical). Pathogen enters the parenchyma, and from here to the alveoli, and the ability of cells to synthesize casein, lactose and fat is ruined. To maintain the osmotic pressure of blood ions of blood in large quantities pass into the milk that contributes to the pH of the samples to 6,76 ± 0,018 for fluctuations indices from 6.65 to 6.87. According to the literature the pH of milk from healthy cows is 6,5–6,6, with the development of inflammation increases to 7–7,5 and more.

Partly affected tissue of the udder becomes permeable to serum proteins. At the same time the total amount of dry matters reduces, quantitative proportion among the components of milk changes. This is reflected in the reduction of the mass fraction of fat, lactose and casein, as well as increasing the content of serum proteins, chlorides and somatic cells.

Mass fraction of protein in the milk of tested cows in the experimental group was an average of 3,02 ± 0,03% (2,84–3,2%), corresponding to basis normal. That is, the total amount of protein did not change, maybe due to increasing of serum proteins.

Under such conditions there are the first changes in protein spectrum of milk whey, first of all concentrations of antibodies to 1,17±0,21 mg / ml increases, which is associated with a protective function of the body against 0,68–0,8 mg / ml serum milk of healthy cows. With the development of inflammation the structure of protein changes, content of N-acetylneuraminic acid decreases.

Thus, at the increase of amount of somatic cells in raw whole milk marked the increase of active acidity and amount of immunoglobulin and increase of level of sialic acids.

It should be noted that  it is important not only the total amount and quality of somatic cells but also their cooperation and correlation that influences on the result of pathological process. These questions are perspective direction of our further research.

Key words: somatic cells, sialic acid, total protein, immunoglobulins.