Background. The rejection of antibiotics in animal husbandry encourages the search for new more effective alternatives, one of which is phytochemicals – small molecules with pronounced bioactive effect.
 Materials and methods. The article discusses the physiological properties of quercetin, 7-hydroxycoumarin, vanillin, trans-cinnamon aldehyde, as active substances from extracts of some plants. Their biological certification was carried out in the bacterial luminescence inhibition test using a recombinant strain of Escherichia coli K12 TG1 in comparison with the antibiotic drug tetracycline.
 Results. Effective concentrations of quercetin, 7-hydroxycoumarin, vanillin, trans-cinnamic aldehyde, suppressing 80, 50 and 20 % luminescence in two media – H2O and scar fluid, respectively, have been established. 9,8×10-4; 4,9×10-4; 6,1×10-5 mol/l for trans-cinnamon aldehyde; 3.9×10-3; 1.9×10-3; 4.9×10-4 mol/l for vanillin; 2,5×10-1; 1,2×10-1; 9,8×10-4 mol/l for quercetin dihydrate; 1,6×10-2; 9,8×10-4; 4,9×10-4 mol/l for 7-hydroxycoumarin.
 Conclusion. Trans-cinnamon aldehyde, vanillin, 7-hydroxycoumarin and quercetin have a pronounced bactericidal or bacteriostatic effect and can be used as an alternative to antibiotic preparations in feeding farm animals, including cattle. In particular, synergistically increasing suppression of the bacterial strain is observed in the environment of the scar content.