An aqueous dispersions of silver nanoparticles (10 ppm, 50 ppm, 300 ppm) stabilized with 100-600 ppm of chloride benzyldimethyl[3-(myristoylamino)propyl]ammonium monohydrate (miramistin) have been used in the experiment. These compositions were registered in Russia in 2014 as a veterinary drug under the brand name Argumistin®. One of the indications for oral and aerosol administration of Argumistin® is respiratory and gastrointestinal infections of broiler chickens. Miramistin-stabilized silver nanoparticles administered at a dose of 0.32 pg of silver per 1 kg of body weight per day almost completely retained in the body of broilers, while the increasing of the administered dose up to 1.92 pg of silver per 1 kg of body weight per day reduced the retention rate up to 30%. With taking into account WHO recommendations and Russian regulations the oral administration of 10 ppm of silver at above mentioned doses can be concluded to fail to cause accumulation of silver in the tissue and organs of broiler chickens in concentrations dangerous for humans.

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The analysis of the epizootic situation for viral arthritis-encephalitis of goats in the territory of Novosibirsk region was carried out. No specifi  c prophylaxis for this disease has been developed, so the earliest diagnostic methods, as well as the study of its epizootology, are relevant. The studies were conducted in 2019. To study the distribution of goats that are positively responsive to viral arthritis-encephalitis, 198 blood serum samples were taken from goats of various genders, breeds and ages in private farm households and farm enterprises located on the territory of Novosibirsky, Iskitimsky, Ordynsky, Kochenevsky, Moshkovsky and Maslyaninsky districts of Novosibirsk region. In order to study the presence of antibodies to goat arthrit-isencephalitis virus in diagnostic titers, an indirect enzyme-linked immunosorbent assay was used with the antibody detection kit against MVV / CAEV in goat serum (ID Screen® MVV / CAEV Indirect Screening test). Of the 198 animals examined, 86 were found to have diagnostically signifi  cant titers of antibodies to the goat arthritis- encephalitis virus, which was 43.4% of the studied population. The result for two goats was uncertain, which amounted to 1%. The remaining animals (55.6%) had no antibodies to goat arthritis-encephalitis virus in their blood serum. The maximum number of positively reacting animals was noted in Novosibirsky district – 66.7%. The Maslyaninsky district was second according to the degree of virus carrying, whereby 47.5% of blood serum samples of goats showed a high titer of antibodies to the goat arthritis-encephalitis virus. The data obtained indicate that at least fi  ve districts of the Novosibirsk Region have foci of goat arthritis-encephalitis virus.

The results of studying the immune response with persistence of the microorganism of the genus Mycoplasma in the body of cows are presented. The study (2019) was conducted in dairy farms in five districts of Novosibirsk region. Identification of individual specific antibodies of class G to microorganisms of the genus Mycoplasma was carried out in 186 samples of blood serum of cattle. The study was carried out by enzyme immunoassay with the MycoplasmaIgG antibodies ELISA VET kit. In the majority of the studied farms, a prolonged persistence of the microorganism of the genus Mycoplasma was noted. It was found that mycoplasma, having weak immunogenicity, mainly causes a chronic course of the disease. In an enzyme-linked immunoassay, this phenomenon was recorded in dubious reactions in 60.8% of animals. In some farms during the study, a period of reactivation of the disease was noted, which appeared in the transition of the disease from the carrier phase to the active form with clinical manifestations. In the enzyme immunoassay, 7.5% of the animals reacted positively. It was noted that in farms with positively reacting animals, the probability of isolation and spread of the pathogen from sick animals is high. No reaction to the presence of class G antibodies to microorganisms of the genus Mycoplasma was detected in 31.7% of the animals studied. In most farms, the growth dynamics of animals with dubious response was noted to depend on their physiological period. The connection of the duration of cow lactation with the dubious antibody response in an enzyme-linked immunosorbent assay was established. The possibility of connecting this phenomenon with highly intensive use of productive animals, which leads to an increase in stress levels and a decrease in homeostasis and immunity, is shown.