EN
The mixture of colistin and tylosin was tested under field conditions in infections of poultry, pigs and calves. The examinations showed that colistin and tylosin (50 000 i.u. per 100 g) administered for prophylactic purposes at the dose of 1 g/4 1 for 5 days was an effective drug in the prophylaxis of infections in chickens in the perihatching period. A therapeutic dose of the drug, i. e. 1 g/2 1 given for 4-5 days was effective in the treatment of colibacteriosis in poultry and in piglets (doses: 1 g/10 kg of body weight, twice). The period of the treatment was 4-5 days. The mixture proved to be effective against infections caused by gram-positive and gram-negative bacteria and also in mixed infections (due to E. coli, Mycoplasma sp. and Salmonella sp.).