[Blood concentrations and anti-Borrelia anserina activity of erythromycin salts in birds].

Tested was comparatively the antispirochaetal activity of erythromycin asparaginate (EA), thiocyanate (ET), and lactate (EL) in a total of 314 chickens, pullets and cockerels artificially infected with Borrelia anserina (strains Surnevo and Pamoukchii). The antibiotics were applied via the crop, with the drinking water, and subcutaneously. The general status of the birds mortality rate, spirocheataemia, and the blood level of antibiotics were followed up along with the effect of EA and ET on the post vaccinal immunity against spirochaetosis. The crop application of EA, ET, and EL at rates of 25000 and 50000 IU/kg from the day of infection for 3 days produced a good prophylactic effect (with single birds only there was transient spirochaetaemia without death cases). At 15000 UI/kg the prophylactic effect was very weak. EA, ET, EL at 120, 180, 250, and 300 IU/kg with the drinking water, and at 150000 and 350000 UI/kg with the feed in the course of 3 to 7 days from the day of infection did not have satisfactory antispirochaetal effect because the birds did not readily accept the medicated water and feed. A comparatively better antispirochaetal effect was established with EA and ET. These antibiotics were found not to inhibit the conference of post vaccinal immunity. Highest blood levels and longest retention were by EA. Very good results were obtained with the subcutaneous application of EA at 25000, 18000, and 15000 IU/kg, once daily in the course of 3 days from the day of infection.