The paper presents the results of serological and bacteriological studies of materials from sheep for ovine infectious epididymitis of sheep, performed in state veterinary laboratories of the constituent entities of the Russian Federation in 2019. In total, during 2019, 384 735 serological studies of blood sera from rams and sheep were carried out in order to identify specific antibodies for infectious epididymitis in the reaction of long-term complement binding (RLCB). Positively reacting animals were found in 13 regions of the Russian Federation (0.04 %). The largest number of serological tests for infectious epididymitis was carried out in the Republic of Dagestan (56 387) and the largest number of positively reacting animals, was revealed (75), which amounted to 43.8 % of all positive cases in the Russian Federation. According to the results of complex bacteriological diagnostics of 216 aborted fetuses and 24 samples of pathological material from sheep for brucellosis, including ovine infectious epididymitis, performed in state veterinary laboratories of the constituent entities of the Russian Federation in 2019, the culture of the pathogen was not isolated. Conducting mass serological diagnostics of the disease in the reaction of long-term complement binding (RLCB) makes it possible to identify positively reacting animals and control the epizootic situation of ovine infectious epididymitis in the constituent entities of the Russian Federation.

In two farms of the Neklinovsky district in the SEC collective farm «50 years of October» and the SEC kolkhoz «Limanny» conducted bacteriological studies of biological materials from cows and calves, which found the presence of E. coli in the vagina, amniotic fluid after calving and in milk samples. In the SEC collective farm «50 years of October» in the first barn from 14 studied cows isolated culture of Escherichia from amniotic fluid in the amount of 7 cultures, vagina - 7, feces - 6, milk - 8. Examined feces from 14 newborn calves. Studies have shown that from 14 samples of feces of calves was isolated by 11 cultures of E. coli. A total of 70 samples were studied in the first barn, 39 E. coli cultures were isolated. In the third barn from 7 studied cows the causative agent of escherichiosis was isolated from amniotic fluid in the amount of 3 cultures, vagina - 2, feces - 2, milk - 4. Examined feces from neonatal calves 7. Studies have shown that 6 Escherichia cultures were isolated from 7 samples of faeces of calves. A total of 42 samples were studied in the third barn, 17 E. coli cultures were identifled. In SPK collective farm «Estuary» in the barn of the 12 cows studied isolated cultures of E. coli from amniotic fluid of 7 crops of the vagina - 7, feces - 2, - 9 milk. Examined feces from 12 newborn calves. Studies have shown that 11 E. coli cultures were isolated from 12 samples of faeces of calves. A total of 60 samples were examined, 36 E. coli cultures were isolated. Infection with E. coli of newborn calves occurs both intrauterine and aer birth, when newborn calves are watered with the milk of a sick mother, as well as in contact with objects of the environment that are infected with Escherichia. This suggests that the disease in the farm is chronic. The source of the illness echrishiosis are mother cows

The article provides data on the study of acute and chronic toxicity of the new anthelmintic compound «K-55». For the acute experiment in rats, the following doses for single intragastric administration were determined: 50 mg/kg, 300 mg/kg, 500 mg/kg, 700 mg/kg, 1000 mg/kg and 2000 mg/kg. In studies of chronic toxicity of a new compound, animals of the first group received 1/10 of the maximum administered dose of the compound (200 mg/kg), the second - 1/20 (100 mg/kg), the third dose was approached to therapeutic one (20 mg/kg). In rats of the experimental group that received the compound at a dose of 200 mg/kg, a decrease in the number of erythrocytes by 25.3 %, leukocytes by 41.7 % at p ≤ 0.05, monocytes by 28.9 %, lymphocytes by 6.9 % was noted and the level of hemoglobin by 5.4 %. As well as an increase in the number of platelets by 30.5 % at p ≤ 0.05 and segmented neutrophils by 36.7 %. But the differences to the control values were not significant. It has been established that this agent, according to the parameters of acute toxicity, belongs to the 3rd hazard category (moderately hazardous substances) according to GOST 12.1.007-76 «Classification and general safety requirements». Thus, the compound «K-55» can be used for clinical trials on animals and be approved for production.

The article presents the results of a study of the cultural properties of bovine adenoviruses: Bovine-10 (serotype 1), Bovine-19 (serotype 2), WBR-1 (serotype 3), THT-62 (serotype 4), B/4 65 (serotype-5), 671/130 (serotype 6), Fucuroi (serotype 7), Misk (serotype 8), Sofa 4/67 (serotype 9), Standel (serotype 10), CLB isolates and Rus 18/81 identified as the first and seventh serotype. Adenoviruses with 1-10 serotypes were cultured in continuous cell cultures of PT-80 (calf kidney), MDBC (cow kidney), TR (cow trachea), Taurus-1(T-1) (calf kidney - fibroblast-like clone) cells for 15 passages, as well as in primary culture of TB cells (bull testicles). The culture medium MEM with a double set of amino acids with the addition of 10 % of fetal bovine blood serum was used as a nutrient medium. The cell monolayer was grown in a CO2 incubator at a temperature of 37 °C. Virus titers were taken into account after the 15th passage, which ranged from 5.0 to 8.86 lg TCD50/ml. The titer of infectious activity was determined according to the method of Reed and Mench, expressed in lg TCD50/ml

We studied the immunobiological properties of the associated vaccine against myxomatosis, pasteurellosis and rabbits hemorrhagic disease types 1 and 2, which consists of two components. Liquid component - antigens of inactivated hemorrhagic disease virus (RGDV-I and -II) and antigen of inactivated pasteurellosis bacteria (P. multocida serotype A), in the form of a mixture on a solution of aluminum hydroxide gel. The dry component is the attenuated rabbit myxomatosis virus (strain «Mixo / ARRIAH-18»). Before use, the components were mixed in predetermined proportions and inoculated intramuscularly in rabbits. The reactogenic, antigenic and protective effects of the combined preparation were evaluated. The following is defened. Тhe reactogenic effect of the drug in the form of a local inflammatory reaction can persist up to 12 days after injection. The accumulation of serum antibodies to a stable protective level to all antigenic components occurs 14 days after immunization. The maximum level of protection for positive control to the virus of hemorrhagic disease types I and II, completely protective level of immunity to pasteurellosis and index of protection against myxomatosis, exceeding three orders of magnitude the drug is able to create to a 28 days after vaccination. An important advantage of the associated vaccine over the known commercial analogs is the possibility of using the drug as a single intramuscular injection, without resorting to multiple vaccinations of animals against each disease, reducing labor costs and stress of animals.

The study of immunological relationships in the functional system «mother-placenta-ospring» can make a significant contribution to the solution of the issue of increasing the safety of the livestock of newborn animals. The reason for significant mortality rate may be the pathology of pregnancy, which is characterized by toxicosis, fetal mortality and the birth of an unviable ofispring. The pathology of antenatal development in animals has not been adequately studied. Antenatal pathology of animals often manifests itself in the form of congenital malformations (anomalies) of development. Congenital malformations are usually called defects that have arisen during intrauterine development. However, congenital defects are also observed during postnatal development, as a consequence of the violation of the further formation of organs in animals. There is a need to develop a method for determining the immunological reactivity of an animal organism, which would allow assessing the combined functional state of the cell-mediated immunological reactivity of innate and acquired immunity in the mother-placenta-ofispring functional system and to determine the factors causing immunosuppression. Determination of the immunological reactivity of the organism of animals included the study of blood by conducting a biological test, which is used as the biological activity of erythrocytes in the HCT test and in terms of their sorption activity - more than 40 % of the animals are classified as individuals with reduced immunological reactivity among a homogeneous sample.

The aim of the study was to analyze the dynamics of morphometric parameters of the sheep spleen in postnatal ontogenesis when feeding the biologically active drug «Gamavit». We studied macro- and micro-morphometric parameters: absolute weight, length, width, thickness, relative area of the parenchyma, its constituent elements - red and white pulp, as well as the relative area of the stroma. The material for the study was newborn, five and nine-month-old sheep from private farms in the Rostov region. We used macro- and micromorphometric techniques. In the experiment, a complex preparation «Gamavit» was used, which has an immunomodulatory and general biotonic effect. The drug applied prophylactically at a dose of 0.1 ml / kg of body weight to animals of the experimental group at the age of nine months for ten days. The authors studied the dynamics of morphological changes in the spleen of sheep when using a biologically active drug. The most significant increase in the studied morphometric parameters of the spleen in sheep was in the period from birth to five months: in the absolute weight, 14.3 times; the width and thickness grew the same 2.5 times, the least of all changed the length by 1.3 times. The relative area of the spleen parenchyma in sheep decreased with age, mainly due to a reduction in the area of the white pulp. It was found that the absolute indices of the lymphoid tissue of the spleen of sheep treated with the drug «Gamavit» were higher in all age periods in comparison with the indices of the animals of the control group, which indicates a positive effect of the drug.

The article presents the results of studying the feed additive Bioactive Keratin in terms of some quality and safety indicators. When assessing the quality of Bioactive Keratin, it was found that the feed additive is a molecularly dispersed substance of a gray-beige shade with a slight sulfur odor, the dry residue content is 3-10 %, the amount of the main component (keratin) is 95-98 % of the dry residue. The product has a slightly alkaline pH of 6.5-7.5; the total microbial count does not exceed 1x102 CFU/cm3. The Bioactive Keratin hydrolyzate contains 16 amino acids, which confirm the bioactivity of the product. At the same time, the content of essential amino acids of the total amount is 43.8 %, conditionally irreplaceable - 12.5 %, to interchangeable - 43.8 %, the ratio of essential and conditionally essential amino acids to interchangeable - 1: 0.8. It has been proven that Bioactive Keratin belongs to the IV class of toxicity (LD50> 5000 mg/kg). The results of assessing the quality and functional properties of Bioactive Keratin indicate the possibility of adding it to the main diet as a feed additive.

The physiological status of dairy cows has been studied. By cows within 120 days after calving, were fed the feed additive «Ketostop-El», 300 g per head, in addition to the ration. The clinical status of healthy animals did not change after the supplement was used. However, clinical improvement was recorded in two cows with symptoms of bursitis and gastrointestinal dysfunction. The inclusion of the supplement in the diet of cows contributed to an increase in the concentration of hemoglobin in the blood, hematocrit and the concentration of hemoglobin in the erythrocyte to physiological values. The number of basophils and eosinophils in the blood of animals increased by an average of 2.3 and 3.6 times compared to their level before the addition to the ration. The level of all metabolites of the blood serum of dairy cows, except for the concentration of triglycerides, corresponded to the average values. It should be noted that the concentration of creatinine in the blood serum decreased by an average of 1.5 times, glucose - by 26 %, total calcium - by 16 %, the ratio of calcium and phosphorus - by 44 %, reserve alkalinity - by 26 %. LT activity decreased by 19 %, AST - by 1.7 times. At the same time, the content of inorganic phosphorus increased by an average of 48 % compared to their amount before the supplement was included in the diet, and at the same time did not go beyond the reference values. At the same time, the use of «Ketostop-El» contributed to a decrease in urine pH to 7.7 ± 0.1, protein content - to 0.35 ± 0.05 g / l, ketones - to 0.35 ± 0.02 mmol / l. The proposed dose of the feed additive «Ketostop-El» (300 g per head) to increase milk productivity, prevents food stress, exerting a positive effect on the body of animals, and makes it easier to adapt to the conditions of the farm.