Mycoplasma gallisepticum is a cause of respiratory disease, egg-productions drops, and reduced feed conversion. Severe airsacculitis, coughing, rales and poor growth may be observed in broilers, with heavy condemnations at processing. MG is egg transmitted, and may be spread laterally by direct or indirect contact. Mycoplasma infections of poultry may be readily confused with other respiratory diseases and may be obvious only when present in conjunction with complicating respiratory infections such as Newcastle disease or infectious bronchitis. Antibodies in serum can be detected by the Enzyme Linked Immunosorbant Assay (ELISA). However, other serologic testing methods such as serum plate agglutination and culturing techniques are recommended for confirmation of infection. The levels of MG antibodies in serum, as well as the immune status of entire flocks can be monitored using ELISA. 

Inactivated antigen is bound to a microwell. Diluted sera is added to the microwell and incubated. Any anti-MG antibodies present in the serum will bind to the MG on the microwell forming an MG antigen-antibody complex. After washing away any unbound material, anti-Chicken IgG Alkaline Phosphatase conjugate is added to the microwell. The conjugate will bind to the MG antigen-antibody complex. After incubation any unbound conjugate is removed by washing. Enzyme substrate is then added to the microwell. The substrate reacts with any Alkaline Phosphatase present and forms a yellow product. In the final step the reaction is stopped, fixing the color. The intensity of the color is measured photometrically at 405 - 410 nm.