[Bioavailability of erythromycin and colistin in calves (author's transl)].

Bioavailability of erythromycin and colistin was studied in plasma, ruminal liquid and nasal mucus after simultaneous injection by intraruminal or intramuscular route. After intramuscular injection, erythromycin was found in plasma and respiratory tract, colistin in plasma. After oral administration, only erythromycin was found in nasal cavity secretions but nitrogen metabolism and volatile fatty acid production were modified in rumen.