A Study On Epidemiology And Synthetic Preventive Measures For Broiler Chickens Infected With Mycoplasma Gallisepticum In Shandong Area

Trials and investigations were conducted to determine the epidemiological characteristics of chronic respiratory disease (CRD) and the effects of breeders' vaccination on the infections of them and their offspring with mycoplasma gallisepticum (MG), and influences of drug prevention and their housing conditions on the morbidity of breeders and broilers with the same disease. 1356 broiler breeders out of 26 flocks on 4 farms were randomly sampled for serum plate tests, which demonstrated that MG positive rate reached 51.47% on the average, 85% max.. Each of the breeders vaccinated against MG produced 8.3 more healthy chicks than those unvaccinated (control), while no significant influence was found on the rate of infection with MG of their offspring. Morbidity for CRD of commercial broilers flocks were largely related to conditions of their houses, so environmentally controlled houses were better than those simple in regard to preventing CRD. Five strains of MG from different areas have been isolated and identified for antibiotic sensitivity tests, which indicated that most of them were sensitive to Tylosin and Tymiosin. In order to determine the effects of the early used drugs on the MG infection, a test was conducted by using 28000 1 day-old broiler breeders divided randomly into two groups of the drug-treated and control. The result showed that the treated revealed low positive rate even negative (0%) at 15, 24 and 28 weeks of age, while the control were as high as 55.9% positive. Egg production and healthy chicks increased by 5% and 1.83% respectively over control group. Furthermore, the commercial broilers, likewise, treated with the drugs also give better performance (higher survival rate and heavier finish weight) than the control. Thus, it is suggested that early (1-3 days of age) medicinal prevention with the drugs above is useful to chicken against MG during their lifetime and synthetic methods such as strict disinfection, sanitation, vaccination and good management, etc. be recommended as well.