Erythromycin is usually a bacteriostatic agent, but in high concentrations or against highly susceptible organisms it may be bactericidal. The macrolides (erythromycin and tylosin) are believed to act by binding to the 50S ribosomal subunit of susceptible bacteria, thereby inhibiting peptide bond formation.
Effective against Gram positive bacteria (Bacillus sp., Staphylococcus sp., Streptococcus sp., Corynebacterium sp., Erysipelotrix rhusiopathiae), Gram negative aerobe bacteria (Actinobacillus sp., Campylobacter sp., Leptospira sp.), anaerobe bacteria (Clostridium sp., Bacteroides sp. (except B. fragilis), some Fusobacterium sp., Actinomyces sp., anaerobe coccus). Moderately susceptible are Pasteurella sp., Haemophilus sp., Enterococcus sp., some Bordetella sp., Legionella sp., Ehrlichia sp.
Ertruth is rapidly absorbed from the upper intestines. Reaches peak plasma concentration in 1-2 hours and diffuses into all body tissue and fluids. High concentrations in liver, lungs and kidneys. Elimination is via bile and in lesser amounts via urine. 

ERTRUTH 35% WSPis effective in chicken against respiratory system diseases, onic Respiratory Disease (CRD), air sacculitis, infectious coryza, Ornithobacterium rhinotrachale infections, infectious sinusitis, staphylococcus and streptococcus infections.

Pharmacological dosage:21 mg/kg live weight/day
Practical dosage:60 gr Ertruth 35% / 1000 kg live weight.
Treatment period:3-5 days
To be mixed into drinking water which should be the only water source available.
Must be prepared on a daily basis. 

20 gr, 100 gr, 500 gr, 1 kg and 2.5 kg.