1965 Volume 18 Issue 3 Pages 114-119
On a poultry farm exposed to infection with avian respiratory mycoplasmosis, 160 69-day-old chicks were divided into five groups. Four groups were administered with chlortetracycline, oxytetracycline, a mixture of streptomycin and dihydrostreptomycin, and tylosin, respectively, so that evaluation might be carried out on the effect of each antibiotic for the prevention of avian respiratory mycoplasmosis. The remaining group served as an untreated control.
1) Judging from clinical symptoms, increase in body weight, and results of isolation of nonpathogenic pleuropneumonia-like organisms from tracheal mucus, chlortetracycline and tylosin seemed to be effective for the prevention of mycoplasmosis.
2) The number of birds giving a positive aglutination reaction to mycoplasmosis and that of birds affected with sinusitis were much smaller in any of the experimental groups administered with the drugs than in the control group.
3) In the experimental groups, except one which had been administered with the mixture of streptomycin and dihydrostreptomycin, chicks positive for agglutination reaction to infectious coryza appeared during the experimental period.
4) Isolation of Mycoplasma gallisepticum was negative in all the chicks, including those of the control group, at the time of autopsy. Accordingly, it was impossible to clarify any germicidal effects of the drugs in the body.
