The paper demonstrates examination results of antigenic properties ofAvibacterium paragallinarumreference strain and ten isolates thereof recovered in the Russian Federation and Republic of Belarus. Nine isolates and the reference strain demonstrated type L hemagglutinin (thermoliable, trypsin-sensitive, active against fresh and glutaraldehyde-treated RBC). One isolate was marked by type Hl hemagglutinin (thermoliable, trypsin-resistant, active only against glutaraldehydetreated RBC). The reference strain antigen proved to be inagglutinable by homologous antiserum, and unable to agglutinate RBCs due to hyaluronic acid in the capsular substance. Serological and hemagglutination non-reactivity was removed through the cell treatment with hyaluronidase. The agglutination test demonstrated that seven out of ten tested isolates belonged to the same serological group; herewith, the proportion of the bilateral antigenic relatedness amounted to ≥78.4%. HI results demonstrated ≥92.6% antigenic relatedness of the tested isolates being indicative of the fact that they belonged not only to the same serological group but also to the same serotype. No serological relatedness was identifed between the tested isolates and reference strain of serogroup A both using agglutination test (≤23.6%) and HI (≤12.2%). Polymerase chain reaction demonstrated that all the isolates recovered in the Russian Federation and Republic of Belarus in 2014-2016 belonged to serogroup B.

The main trend in the development of dairy farming in the Russian Federation suggests maximising milk yield and reducing milk net cost. The economic effectiveness of industrial dairy farming is largely determined by adequate feeding, as well as effective system of measures to ensure animal health and prevent infectious and non-infectious mass diseases. The main reason for the premature retirement of highly productive cows is based on the factors typical of the intensive technologies used in dairy cattle breeding, which lead to the occurrence of metabolic diseases. It is established that the intensity of metabolism is directly linked to the high productivity of cows. With a highly concentrated, mainly silage-based type of feeding, an imbalance of nutrients is often recorded, in particular as regards the sugar/ protein ratio, leading to deep metabolic disorders and the development of immunodeficiency states. Metabolic disorders in highly productive cows occur as a result of unbalanced diets as far as protein, carbohydrates, vitamins and minerals are concerned. Acidosis, ruminitis and hepatosis are recorded in disordered cows and heifers. The service period exceeds 100 days in 70–75% of cows. Hepatosis and immunodeficiency states are often found in calves born to cows with signs of deep metabolic disorders. Metabolic disorders often remain unnoticed and become apparent only when pronounced pathological changes occur resulting in decreased productivity and ability to reproduce resistant young animals, as well as culling of animals. Metabolic diseases were recorded in 30–70% of cows examined in large dairy farms. The average lifetime productivity of high-yielding cows is (2.1 ± 0.15) lactations in Russia. The results of epidemiological investigations and laboratory testing of sera samples showed that emulsion inactivated vaccines administered to immunodeficient cattle induce higher titres of virus-specific antibodies than those in animals vaccinated with adsorbed vaccines.