Thein terim results of the first year of the project,funded by theRussian Science Foundation(RSF), are presented. The study focuses on the species diversity of the symbiofauna of domestic animals bred in Yakutia.A total of 1,760 samples were collected from various types of domestic animals and analyzed. The research identified and described 98species of endobiontsin ruminantsand25species in horses (based on2breedtypesof theYakutbreed). Additionally, severalr are species of ciliates were discovered during the study. Notably, this study is the first to compare the diversity of Yakut aboriginal cattle with crossbred and Simmental cattle. The findings reveal that the endemic Yakut cow, bred under conditions of poor, low-nutrient feeding during along winter period, has developed an adaptive functional feature, such as a diverse symbiont fauna of protozoa, to facilitate the complete breakdown and absorption of limited nutrients in the feed. Furthermore, the study found no significant differences in symbiofauna between the Even and Chukotka reindeer breeds, which differ in their breeding zones.In the Even breed of deer, a total of 13 species were identified, while in the Chukchi deer, 11 species from six genera were found. In domestic sheep and hybrids (which are half domestic sheep and half wild bighorn sheep), 12 ciliate species were identified, buttheir diversity did not differ. In theYakuthorsebreed,15 species of endobiont ciliates were identified, of which 11 are indigenous and 14 are of the Yan type. This research provides the first data on the endobionts of herd horses of the Yanatype of the Yakutbreed. Thestudied populations of herd horses were characterized by are latively high level of end obiontdiversity. The species similarity between two populations of the Yakut horse breed, bred in different geographical zones, was demonstrated. This research has identified the symbiotic fauna of domestic animals and established a connection between the species composition of the symbiotic fauna and the habitat of the animals, including their social behavior.

In this article, the authors present the results of a helminthological study of the Vulpes lagopus in the Arctic territory of Yakutia. On the territory of Yakutia, three species of representatives of the Canidae family live in a wild state - the wolf, the red fox and the Arctic fox. Representatives of the Canidae family are among the most important commercial animals whose fur is highly valued. Over the last decade, the number of fur-bearing animals in the tundra zone of Yakutia has increased significantly. As the authors point out, monitoring of the epizootic situation for especially dangerous Helminthiasis is an integral part of a set of measures to preserve the health of animals and the population in the Arctic zone. The objects of the study are Arctic foxes. Materials for the study were brought from December to March in 2020 from 26, 2021 - 36, 2022 - 162, 2023 - 121 Arctic foxes, carcasses, internal organs and tissues. According to the results of helminthological studies, the composition of helminths was represented by 16 species. The main components of the helminth fauna, in terms of frequency of occurrence and very high rates of invasion intensity, are: the cestode Alveococcus multilocularis, found in 98.1% of the studied Arctic foxes, up to 18,000 ind. of mature Alveococcus in one animal, the nematode Toxascaris leonine occurs in 92.1%, on average up to 34.8±1.6 ind. for one Arctic fox. Also, it was found that the infection of arctic foxes with larvae of Trichinella spiralis is 3%, high intensity of invasion, the cestode Diphyllobothrium latum were infected with up to 5.5% of the examined, on average, 3.5 sp. for one Arctic fox.

Brucellosis of reindeer in the Far north of the Russian Federation is widespread, is a significant deterrent to the further development of reindeer husbandry and continues to pose a serious social danger. Despite the fact that the situation with reindeer brucellosis has improved markedly recently, it should still be recognized that this problem has not been completely solved. At the same time, along with general preventive measures, the priority in this system remains the creation of high specific protection against brucellosis in animals. The aim of the work was to study the phenotypic and genotypic properties of Brucella rangiferi strains isolated from reindeer in comparison with some strains of the genus Brucella. The result of the research was the study of isolated strains in different years from reindeer in Russia, B.suis biovar 4 (B.rangiferi) in comparison with reference and vaccine strains of brucella. We selected a strain of B.rangiferi 1069, which was less susceptible to dissociation, and also less sensitive to penicillin and erythritol. This strain was determined as the base one when creating laboratory samples (series) of an inactivated emulsin vaccine from brucella of the suis species (biovar 4) against reindeer brucellosis. Thus, the problem of specific prevention of brucellosis of reindeer, despite the considerable scientific material available, remains almost not completely solved to date. However, the available (accumulated data of many authors), as well as our data, already allow us to recommend to production a scientifically based system for the prevention and control of brucellosis of reindeer in the Republic of Sakha (Yakutia). The introduction of a scientifically based system significantly reduces the intensity of the epizootic process for reindeer brucellosis in the whole region. The use of means of specific prevention of brucellosis in the general system of anti-brucellosis measures makes it possible to sharply reduce the intensity of the epizootic process in reindeer herds and to achieve the elimination of epizootic foci of brucellosis within 20-24 months. Without highly effective means of immunoprophylaxis and a clear scheme of their use, a successful fight against brucellosis of reindeer is impossible. Consequently, the further search for new and development of technology for the use of available means of immunoprophylaxis of brucellosis of reindeer, especially inactivated vaccines, should not stop.

The system of anti-brucellosis measures requires constant improvement in order to increase its effectiveness and reliability. At the same time, the priority remains the creation of high specific protection for brucellosis in animals. Live vaccines from agglutinogenic strains of B.abortus 19, 104M and 82 turned out to be the most immunogenic and effective in antiepizootic relation. As a result of the conducted studies, it was found that the most pronounced general and local reactions were noted in calves vaccinated subcutaneously with a standard dose of vaccine from strain 19, less pronounced in vaccinated with vaccine from strain 104M and weakly in vaccinated with vaccine from strain 82. According to the results of serological studies of blood serum, it can be seen that all animals (100%) reacted in calves for 10-20 days after immunization with vaccines from strains 19 and 104M, and only 40% of calves vaccinated with vaccine from strain 82 reacted. At the same time, calves vaccinated with the strain 19 vaccine reacted in RA in the titers 400-1600 ME. Vaccine from strain 104M - in titers 400-800 ME, vaccine from strain 82 - in titers 25-50 ME. According to the results of serological studies, the state of tolerance was not noted in calves received from re-immunized cows after immunization with agglutinogenic anti-brucellosis vaccines. Further study of the dynamics of antibodies after the introduction of vaccines from strains 19, 104М and 82 by subcutaneous method in a full dose to calves of 3-5 months of age received from re-vaccinated cows showed that the timing of the maximum rise and extinction of the titers of agglutinating and complement-binding antibodies in the blood serum of vaccinated animals is also directly dependent on the properties of the vaccine used. Thus, as a result of serological studies, it was found that the repeated reimunization of pregnant cows with vaccines from strains B.abortus 19, 104M and 82 have no significant effect on the immunological reactivity of the offspring obtained from them, which is confirmed by the absence of a state of tolerance in calves after immunization with agglutinogenic anti-brucellosis vaccines.

The article presents materials of study of antigenic, virulent and immunogenic properties of B. suis 245 strain brucelle culture in a comparative aspect with other vaccine strains in the body of laboratory animals. Transfers were made from the strains B. suis 245, B. abortus 19, 82, B. melitensis Rev-1 on dense nutrient medium after growth of lyophilized cultures of brucellas. A bacteriological study was conducted on meat-pepton glucose-glycerin broth (one test tube per object) and meat-pepton hepatic-glucose-glycerin agar (two test tubes per object) of pathological material (ten objects from each of the test animals). The identification of the isolated cultures of microorganisms was carried out by establishing an agglutination reaction on the glass with S- and R-anti-brucellosis serums. Regardless of the vaccine injection method, all animals that have been vaccinated with the B. suis 245 vaccine have shown resistance to artificial infection with virulent brucellosis. It was noted that in the group of guinea pigs vaccinated with a drug from the B. melitensis Rev-1 strain, resistance to infection was quite high. The protective properties of brucellosis vaccines are monitored in mice 10 days after vaccination. The test animals follow the observation for 7-10 days.

Purpose: Determination of the peculiarities of the behavior and the flow of childbirth in females (wrenches) of the northern home deer of the Even Breed of the Republic of Sakha (Yakutia), depending on the natural climatic zone of breeding. Material and research methods. Research of the reservation of the hotel's reservoir of the northern home deer was held from April to June in the reindeer herds of the mountain-taiga (FSUE «Yuchjuyuskoye») and the Tundrov zones (SHPZK «Taba-Yana») of the Republic of Sakha (Yakutia) in the conditions of nomadic home reindeer herding since 2013 2018 In the study, the method of observation is used with the registration of motor activity of animals and the activities of individual bodies in a certain living environment. Results. To fix some patterns and species features of the generic process, 8 main elementary behavioral reactions spent venizables of northern domestic deer per day before childbirth: walking, feeding feed, chewing, leisure standing, rest lying, sleep, urination (how many times / total time), defecation (how many times / total time). Also marked 4 behavioral reactions on the hotel day: the exploitation time of the fetus, the licking of the calf, the time of the calf on his feet after delivery, the first reception of the mosper calf after birth. For each parameter, data reflected in tabular format is obtained. Conclusion. It has been established that the degree of adaptation of the northern domestic deer to the harsh conditions of existence in various natural-climatic zones of the Republic of Sakha (Yakutia) is very high, which is manifested in a minor difference in the duration of the generic process and behavioral reactions at the vainer of the mountain and tundra and tundra dilution zones.

Currently, live vaccines are mainly used to prevent brucellosis in animals. The effectiveness of such vaccines is a time-tested fact. However, live vaccines have many disadvantages, they can cause abortions in vaccinated animals, some vaccine strains migrate to unvaccinated animals, and pose an epidemiological danger. In addition, there is a problem of postvaccinal antibodies, which complicates the differential diagnosis of immunized and sick animals. When receiving a weakly agglutinogenic vaccine, it is important to choose a specific protective antigen, since the antigenic set of any bacterium, including brucella, is very large, and not all antigens are of equal importance in the formation of immunity. Studies were conducted on rabbits and guinea pigs that react negatively to brucellosis. Before and after vaccination, the antigenic activity of the test vaccine and the level of antigen-binding lymphocytes with a receptor for the protective brucella antigen were determined in dynamics. To detect the antigenic activity of LAV, a red blood cell diagnostic was prepared, which was obtained by sorption of the protective brucella antigen on tanized red blood cells. Based on the results of serological and bacteriological studies, it was found that the LAV at a dose of 0.1 mg of antigen is optimal. A dynamic increase in serological conversion in vaccinated rabbits and guinea pigs was observed with the introduction of each dose of the vaccine. Depending on the dose range, the highest peak of seroconversion was observed in guinea pigs on day 30 and in rabbits on day 15 of the study. Thus, the optimal vaccination dose of brucellosis weakly agglutinogenic vaccine with a single administration should be considered: for guinea pigs - 0.1 mg, and for rabbits-0.2 mg. Consequently, the administered dose of the test vaccine affected the induction of agglutinins and depended on the injected dose of the drug, which was reflected in the results of seroconversion. Maximum seroconversion was observed in guinea pigs on day 30, in rabbits on day 15 after immunization.

In the general complex of antibrucellosis measures, specific prevention of the disease occupies an important place. The first experiments on vaccination of animals against brucellosis were carried out in the early 20th century. Experiments have shown that even a single subcutaneous vaccination with a live virulent culture 2 months before fertilization in 90% of cases protects animals from subsequent infection and abortion. Of all the brucellosis vaccines used in different countries, the most widespread is the vaccine from the B. abortus 19 strain, which is used to prevent brucellosis in all farm animals. When studying the dispersal and survival of brucella of the vaccine strain in the body of animals vaccinated with different doses of the vaccine, it proceeded similarly, without significant difference (P>0,05). The infection index in heifers vaccinated with a small dose 1 month after vaccination was 60±2, and in heifers vaccinated with a full dose - 74±4. Two months after vaccination, the infection index was 44±16 and 44±4, respectively. 2 months after vaccination, the total number of isolated cultures was 21% less than in the study 1 month after vaccination. According to the total data, 38.5% of cultures were sown from the pharyngeal and prescapular lymph nodes of heifers vaccinated with a small dose 1 month after vaccination, and 20% after 2 months. In heifers vaccinated with a full dose, 28.1% and 26.9%, respectively. Thus, the results of the experiment showed that the dispersibility and survival rate of brucella vaccine strain B. abortus 19 in the body of heifers slightly depends on the dose of the vaccine, which is consistent with the data obtained by us in the experiment on guinea pigs, as well as with the data of other authors.

Ðåçþìå.Ïðåäñòàâëåíû ìàòåðèàëû ïî èçó÷åíèþ áàêòåðèöèäíîé àêòèâíîñòè ðàçëè÷íûõ ôðàêöèé êðîâè (ñûâîðîòêè, ïëàçìû, ðàçëè÷íûõ êëåòî÷íûõ ïîïóëÿöèé ïîëèìîðôíîÿäåðíûõ è ìîíîíóêëåàðíûõ ëèìôîöèòîâ) îò èììóííûõ è èíòàêòíûõ aeèâîòíûõ â îòíîøåíèè áðóöåëë.Äëÿ ïðîâåäåíèÿ èññëåäîâàíèé êðîâü îò èììóííûõ è èíòàêòíûõ aeèâîòíûõ ðàçäåëÿëè íà ñîñòàâíûå ôðàêöèè ìåòîäîì ãðàäèåíòíîãî öåíòðèôóãèðîâàíèÿ.Ïîñëå èììóíèçàöèè âçðîñëûõ òåëîê âàêöèíîé èç øòàììà Brucella