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The issue of cattle reproduction was and still is one of the main tasks in cattle breeding. Losses of farms from infertility of cows are quite significant and range within 3.19-5.41 per 1 day of infertility. Mycotoxins produced by fungi of the Fusarium family, namely deoxynivalenol (DON) and zearalenone (ZEN) adversely affect not only the functioning of all organs and systems of the cow’s body, but also produce an immunosedative effect. The purpose of this study was to establish the effect of the DON and ZEN complex on the main indicators of the immune response of cows and its correction in a comparative aspect using a feed additive based on zeolite and organic acids and recombinant α-, g-interferons. The study material was the blood of cows (serum and stabilized) sick with mycotoxicosis caused by the association of DON and ZEN. Methods used: photonephelometric using E. coli test culture, spontaneous rosette formation with sheep red blood cells according to M. Jondal, modified method of rosette formation according to M. Wansbrough-Jones, R. Limatibul’s method, simple radial immunodiffusion in gel according to G. Mancini, precipitation in a polyethylene glycol solution according to M. Digeon. Experimental studies were performed on black-spotted cows in farms of the Sumy Oblast. The dynamics of the immune indicators of cows during the development of mycotoxicosis and upon treatment with products zeolite-based, organic acids, and an aqueous solution of recombinant α-, g-interferons were studied. It was found that the indicator of bactericidal, lysozyme, complementary, and phagocytic activity of cow blood serum under treatment increased to the indicator inherent in healthy animals. The dynamics of immunoglobulins in the treatment with zeolite and organic acids and recombinant α-, g-interferons was investigated, and an increase to the level of intact cows was established. It was proved that the indicators of the immune response of cows upon using a feed additive based on zeolite and organic acids at a dose of 2.5 kg per tonne of fodder and a preparation based on an aqueous solution of recombinant α-, g-interferons at a dose of 3 ml per animal were significantly higher

A large number of dairy cows in Ukrainian farms suffer from subclinical mastitis, which leads to significant economic losses in agriculture. Conditioned upon the lack of clinical manifestations it is difficult to detect, in particular, explained by insufficient information about the microbial composition of milk. The ban on the use of antibiotics for productive animals is forcing new safe and effective remedies. The aim of the study was to determine the therapeutic effect of Bacillus megaterium NCH 55 in subclinical mastitis of Holstein cows. Research materials – milk of cows with subclinical mastitis, isolates of microorganisms and B. megaterium NCH 55. Methods used: California test for mastitis; microscopic test to count the total number of somatic cells by the method of Prescott and Britt; bacterial method for the study of microorganisms; polymerase chain reaction to determine Mycoplasma spp. in milk; spectrophotometry; method VI Brillis to determine the adhesive properties of Bacillus megaterium NCH 55; determination of antagonistic properties of B. megaterium by diffusion into agar wells; the method of flow cytometry using the device “SomaCount Flow Cytometer"; physiological. The experiment was conducted in dairy farms of the North-Eastern region of Ukraine: LLC agrofirm “Lan”, LLC agrofirm “Vorozhbalatinvest”, LLC agrofirm “Vladana” in the period February-August 2021. Isolates of S. aureus, S. agalactiae, E. coli enterohemorrhagic, E. coli, Candida, E. fecalis, S. epidermidis and Mycoplasma spp. were detected in milk samples from cows with subclinical mastitis. Microscopic studies have shown that Bacillus megaterium NCH 55 are white gram-positive rods that have low adhesive properties and form spores. The greatest antagonism of B. megaterium is shown in relation to bacterial isolates in concentration of 1×109, CFU/g. In 70% of cows that reached a productivity of more than 30 kg/day on the 30th day of research, milk parameters such as the number of somatic cells (CSC ≤400 thousand/cm3) and the number of mesophilic aerobic and facultative anaerobic microorganisms (kMAFANM) (≤100 thousand CFU/cm3) corresponded to the class “Extra”. The recovery time of animals with subclinical mastitis depended on the degree of damage to the breast and individual characteristics of the organism. Cows that did not reach a productivity of 30 kg/day continued treatment individually. The number of somatic cells in the milk of cows was ≤500 thousand/cm3 and kMAFAnM ≤200 thousand CF/cm3