David P. Anderson

Airsacculitis in broilers from Mycoplasma synoviae: effect on air-sac lesions of vaccinating with infectious bronchitis and Newcastle virus

SUMMARY Broilers vaccinated against infectious bronchitis and Newcastle disease developed airsacculitis following aerosol exposure to broth cultures of Mycoplasma synoviae. Incidence and severity of lesions was maximum 3 weeks postexposure, but few lesions were grossly visible 6 weeks postexposure. In another trial, aerosol exposure of unvaccinated birds or bronchitis vaccination 5 days after mycoplasma exposure resulted in a low incidence of airsacculitis with mild lesions. Vaccination 5 days prior to mycoplasma exposure led to increased severity of airsacculitis, while vaccination and mycoplasma exposure on the same day resulted in the highest incidence and severity of lesions. Aerosol exposure to M. synoviae in broilers vaccinated simultaneously against both infectious bronchitis and Newcastle disease led to depressed growth and less efficient feed conversion.

Field Studies with Mycoplasma synoviae

SUMMARY Mycoplasma synoviae infections have been shown to affect broiler performance as determined by reduced body weight, poorer feed conversion, increased condemnations for airsacculitis and septicemia-toxemia, as well as increased cost of pounds of broilers produced by an integrated broiler-producing operation.SUMMARY Mycoplasma synoviae infections have been shown to affect broiler performance as determined by reduced body weight, poorer feed conversion, increased condemnations for airsacculitis and septicemia-toxemia, as well as increased cost of pounds of broilers produced by an integrated broiler-producing operation.

Classification of avian mycoplasmas by gel-diffusion and growth-inhibition tests

SUMMARY The antigenic relations of 19 serotypes of avian mycoplasma were studied by immunodiffusion and growth inhibition. M. gallisepticum and M. synoviae had no cross reactions with other serotypes. According to the degree of cross reaction by both tests mentioned and the sharing of identical antigenic components by the gel-diffusion test, the 19 serotypes were classified into 9 groups. A modified disc growth inhibition with standardized inocula was adopted. This uses small quantities of antisera and is easy to interpret.

In vitro activity of various antibiotics against Mycoplasma synoviae.

SUMMARY Minimum lethal concentrations (MLC) and minimum inhibitory concentrations (MIC) were determined in vitro for 8 antibiotics against 9 isolates of Mycoplasma synoviae. Of the antibiotics tested, tylosin had the highest activity, followed closely by chlortetracycline, lincomycin, oxytetracycline, spectinomycin, and tetracycline. Neomycin and erythromycin were less effective. Two antibiotic combinations (lincomycin-spectinomycin and oxytetracyclineneomycin) had greater mycoplasmacidal activity than either member of the combination acting alone.

Maternal transfer of resistance against development of Marek's disease tumors.

Studies were conducted to determine the protective effect of maternal antibody on Mareks disease (MD) in progeny from parent flocks vaccinated with the turkey herpesvirus (HVT) or the attenuated Mareks disease virus (MDV). In laboratory trials chickens were inoculated at 1 day of age, at 23 weeks and 27 weeks with HVT or attenuated MDV. Progeny from the two groups (HVT and attenuated MDV) and from an unvaccinated-uninfected control group were exposed to MD either by subcutaneous inoculation with MD-infective plasma or by contact exposure. Chicks free of MD antibody from the control group were found to be more susceptible to MD than chicks from parent stock which had been vaccinated with HVT. Progeny from birds vaccinated with MDV did not receive the protective effect afforded the progeny of the HVT-vaccinated birds. In field trials, progeny from a flock vaccinated once at one day of age with HVT were not found to be more resistant to MD than progeny from the control parent flock. However, in other field trials progeny from parent flocks which had been vaccinated 3 times with HVT were found to be more resistant to MD than birds from control parent flocks.

Aerosol studies with avian mycoplasma. I. Survival in the air.

Grumbles et al. (4) and Fahey and Crawley (2) presented data indicating airborne spread of agents responsible for chronic respiratory disease in chickens. This method of transmission requires that the Mycoplasma microorganisms be discharged from birds in a manner to become airborne, survive in the airborne state, and be infective upon inhalation by susceptible birds. This study was made to determine whether Mycoplasma gallisepticum and M. meleagridis could be recovered, and for what period, from artificially created areosols.

The influence of inhalation of carbon dioxide on chickens, including resistance to infection with Newcastle disease virus.

Carbon dioxide (CO2) is a noncombustible, colorless, odorless, slightly acid gas with a specific gravity of 1.529. It is a natural constituent of atmospheric air and is usually present in concentrations of 300 parts per million (ppm), which is equivalent to 0.030% by volume (15). The practice of rearing chickens and turkeys in confinement during the winter months has led to exposure of these birds to pollutants such as carbon dioxide, ammonia, dust, and air-borne microorganisms that accumulate in the atmosphere of poultry houses. Carbon dioxide is one of the principal metabolic products of heterotrophic microorganisms present in the litter. Its production is a complex rather than a simple function of microbial activity, which is influenced by temperature, aeration, and pH of the litter. The rate and quantity of C02 produced depends not only on the numbers and types of organisms present, but also on the nature and quantity of oxidizable materials (13). Carbon dioxide concentrations as high as 5100 ppm have been found in poultry houses in the North Central states area (2,4). The highest concentrations were at floor level during the night, when bird activity was at a minimum. A considerable portion of the carbon dioxide came from the respiration of the birds, particularly in crowded buildings during periods of reduced ventilation. One of the difficulties experienced in determining the possible toxicity of low concentrations of most atmospheric pollutants is in direct measurement of the effects on the subject. Pulmonary path-

Evaluation of avian mycoplasma membranes as antigens.

Mycoplasma gallisepticum and M. synoviae membranes were obtained by lysing mycoplasma cells with carbonate bicarbonate buffer at pH 10. Membrane preparations were compared with whole-cell preparations as to efficacy in the plate and tube agglutination and hemagglutination-inhibition tests. Membrane antigens were somewhat more sensitive in the plate and tube agglutination tests, whereas the hemagglutination-inhibition test showed no major difference between whole and membrane antigens. The membrane preparations were equal to whole-cell antigens in specificity.