In the development of effective methods of prevention and treatment of poultry today, importance is given to probiotics based on microbial cultures, in particular, lactobacilli, bifidobacteria, yeast, etc. In contrast to antibiotics, the use of probiotics stimulates the immune response of animals, restores the microflora of the gastrointestinal tract, and ensures its optimal ratio. At the same time, livestock products remain safe for the consumer. The purpose of our work was to conduct comparative clinical trials of the efficiency of the probiotic feed additive Probion-forte in terms of productivity, blood indices, and histological structure of immune organs of chicken broilers during fattening. The clinical studies were carried out with broiler chickens of “Cobb-500” cross at the age of 2 days, which were formed into four groups (300 units in each one). In order to determine the efficiency of application, probiotic feed additives were given to chickens in different concentrations during the growing period, together with the main diet. The first group (1st) was given probiotic Probion-forte in the dose of 1 g/kg of feed, the second group (2nd) – Probion-forte in a dose of 0.5 g/kg, the third (3rd) one – a probiotic-analog “Bio plus 2B” in a dose of 0.4 g/kg; the forth (4th) group was a control group – chickens received an essential diet, without adding any feed additives. The compound feed was provided according to norms recommended for the cross “Cobb-500”, considering age. On the 15th, 30th, and 43rd day of the test, 20 units were selected for hematological, pathomorphological and microbiological tests. The productivity of birds of all studied groups was evaluated by the average daily gains, safety, feed conversion, and slaughter output. The stabilized with EDTA chicken blood was used for morphological studies, and blood serum – for biochemical and immunological studies. Comparative clinical studies have shown that adding to the main diet of broiler chickens probiotic feed additive Probion-forte at a dose of 0.5 and 1.0 g/kg throughout the growing period increases the safety and improves feed digestibility, and increases the bird’s European Efficiency Index. Based on the obtained hematological, biochemical, and immunological parameters of blood, it can be argued about the activating effect on the body of broiler chickens probiotic feed additives, namely the intensification of reanimation of free amino acids, which increases the content of the studied metabolites of lipid metabolism, which chickens use as energy and plastic material. Stimulating cellular and humoral protection, nonspecific resistance is established, confirmed by a high level of lysozyme activity in blood serum and significantly higher content of T- and B-lymphocytes, NK-cells, and γ-globulins. The macro- and microscopic structure of the studied immune organs is preserved in all groups of broiler chickens. Compared with the control group, morphometric examination in the immune organs of broiler chickens of the first and second groups revealed an increase in the area and density of lymphoid elements, an increase in the number of plasmablasts and plasma cells, much higher structural and functional capacity of cells, which was reflected at the ultrastructural level. The most significant difference was found in the 1st group of chickens fed with the feed additive Probion-forte at a dose of 1.0 g/kg of feed.

An important feature of living organisms, acquired in the process of evolution, is the ability to adapt to various external influences and changes in the environment, to maintain homeostasis and regulatory processes in organs, systems and the body as a whole. However, with modern breeding technologies, the physiological capabilities of the animal's body are often unable to change as quickly as required by the conditions of industrial maintenance, which leads to stress. Vitamin preparations and biologically active feed additives are widely used by veterinary medicine specialists to increase resistance to stressful situations, disease prevention, increase resistance, safety and productivity of farm animals. Preparation L-tsyn, solution for injection (manufactured by BIOTESTLAB LLC), is a drug, the action of which is due to the prescription combination of active substances, namely: butaphosphane, B vitamins (vitamin B12, vitamin B3) and L-carnitine. The aim of the study was to investigate the effectiveness of the drug L-tsyn on horses under the influence of stressors of various natures. Two experiments on working horses with constant, excessive physical activity with chronic exercises and with complex therapy of intoxication with signs of acute renal failure in horse were conducted. Clinical trials of the drug were performed on working horses aged 5–15 years, of different sexes. The drug was administered in a dose of 20–25 ml per animal, 1 time per day for 5 consecutive days. The clinical condition of the experimental animals was observed for 21 days from the start of the drug. The morpho-functional state of the animal's body before and after the drug was established according to the indicators of the clinical condition, morphological and biochemical parameters of the blood, which were determined according to generally accepted methods. In working horses under excessive load the drug L-tsyn activated the processes of hematopoiesis, improved the physiological state of the body and contributed to the increase the general tone of the body. The drug as part of complex therapy in the treatment of intoxication, showed hepato- and nephroprotective properties, reduced the manifestations of intoxication, helped to restoration of the animal’s normal physiological state. According to the results of clinical, hematological and biochemical studies, it can be concluded that the drug L-tsyn has a stimulating effect on metabolic processes in the animals’ body, shows tonic properties, increases the body's resistance to toxins and adverse environmental factors and can be used as monotherapy and for the complex treatment of diseases of various etiologies in horses.

Recently, interest in the use of bacteriophage therapy in poultry has arisen in the context of the growing problem of antibiotic-resistant microorganisms, as the need to find alternative antibacterial agents is urgent. In addition, EU legislation prohibits the use of antibiotics in feed to stimulate the growth of animals and poultry. Bafasal – a new and innovative agent based on natural components of the ecosystem, has a high specificity to Salmonella serovars, in particular, S. enteritidis, S. typhimurium, S. mbandaka, S. gallinarum, S. іnfantis, which are most often diagnosed in poultry farming. This is the first bacteriophage product on the poultry market, which is recommended as a feed additive for broiler chickens. The article presents the results of studies on the safety of Bafasal under the application as a feed additive for the prevention of bacterial diseases in poultry breeding. Bafasal was used for chickens of the experimental group according to the following scheme: from 1 to 14 days of the experiment – per 10 chickens – 50 cm3 of feed additive dissolved to 0,5% concentration; and from 15 to 35 days – 100 cm3 of the drug dissolved to 0,25 % concentration. Feeding of poultry of the control and experimental groups was carried out with identical feeds in accordance with regulatory requirements, taking into account the age of the bird. The clinical condition of the bird’s body was monitored daily, on the 35th day of the experiment; ten chickens from each group were taken blood samples for further laboratory tests. The morphological and biochemical parameters of the broiler chicken’s blood under the application of Bafasal feed additive were studied. It was found that the hematological and biochemical parameters of broiler chickens in the experimental group were within the physiological norm for poultry of this age on fattening, and therefore corresponded to the status of a conditionally healthy organism without signs of pathophysiological abnormalities. There was a reliable increase, within the physiological norm, in the relative number of lymphocytes by 11, 9 % (p <0,05) and a tendency to increasing the number of leukocytes, which showed a sufficient immune potential of the birds and an increase in cellular factors of natural resistance, compared with control chickens. According to the parameters of mineral metabolism, the serum content of Calcium and Phosphorus within the physiological norm was noted, which indicated a sufficient level of mineral supply of the organism of the experimental birds as a whole. In addition, in chicken fed Bafasal throughout the fattening period, the serum enzyme’s ALT, AST and creatine kinase activities and the content of total cholesterol not differ significantly from the control group, indicating the absence of signs of hepatotoxic effects of the studied feed additive.

Doxycycline is a bacteriostatic antibiotic from the group of tetracyclines, a semi-synthetic derivative of chloretracycline. It is a broad-spectrum antibiotic that is active in gram- positive and gram- negative bacteria, including some anaerobes. Therefore, the use of doxycycline drugs is relevant to solve the problem of treatment and control of mono- and polyinfections, which are caused by doxycycline sensitive and other antibiotics resistant to other antibiotics. The article presents the results of clinical studies of a new veterinary drug Doxal (water-soluble powder for oral administration), production of PJSC “Technologist” (Ukraine), an active pharmaceutical ingredient of which is doxycycline, in the treatment of acute intestinal disease in broiler chickens. A high level of therapeutic efficacy and safety of the Doxal studied drug in the treatment of chickens 25 daily age with colibacteriose-claspidiosis infection was established. The diagnosis was made on the basis of anamnestic data, a clinical picture of the disease, the results of pathoanatomical section and bacteriological examination. Microorganisms – pathogens of infection, their level of sensitivity to doxycycline were selected and identified. Therapeutic efficiency of the tested drug was not inferior to the drug-comparison of Doxatib®, production of KRKA DD Novo-Mesto (Slovenia), similar in dosage form and the content of the active substance. According to the results of laboratory tests, a positive effect of Doxal on the morpho-functional state of the body of chickens in the treatment of acute colibacteriosis-claspidiosis infection was revealed, which is confirmed by normalization with a high percentage of the reliability of morphological and biochemical blood indicators to the values of clinically healthy bird. Comparative clinical studies have confirmed that Doxal drug is effective chemotherapeutic agent for the treatment of bacterial infections in chickens caused by microorganisms sensitive to doxycycline, and is analogous to Doxatib® by it’s action.

To date, special attention should be paid to drugs that have antimicrobial, anti-inflammatory and wound-healing effects, one of which is sodium-containing drugs. The article presents the results of experimental studies to study the acute toxicity of sodium-containing drugs: glycetinate 2 %, its analogues – ovocid 2 %, ovocid 3 %, potassium-sodium 1.5% (Na/K 1.5 %). The study of acute toxicity of drugs was carried out by applying drugs to the skin of animals. The experiment used white rats weighing 250-270 g. 4 groups of rats with 3 animals in each were formed: rats of group I on the skin was applied ovocid 3 %, group 2 - Nа/К 1,5 %, 3rd group - ovocid 2 %, and the 4th group of rats (control) was applied glycetinate 2 %. The animals were subjected to clinical observations, assessing their general condition and skin reaction. The effect of drugs on morphological and biochemical parameters of blood of rats was studied. The studied drugs did not cause visible disorders of physiological functions, the appearance of clinical signs of intoxication. There were no significant clinical signs of inflammation or irritation (erythema, edema and cracks) on the skin of the animals, but there was a slight redness at the application site, which later disappeared. The studied sodium-containing preparations (ovocid 3 %, Nа/К 1,5 %, ovocid 2 %, glycetinate 2 %) under the conditions of a single application of the preparation to the skin of animals did not cause the death of animals, which allows us to classify these preparations as low-toxic substances.