Propagate Law Of Mycoplasma Synoviae And Source Of Infection In An Egg Breeding Farm

Mycoplasma synoviae(MS)is a poultry pathogen that usually cause chronic disease. It is responsible for synovitis and respiratory tract disease in chickens and turkeys. Infected chickens show joint exudative synovitis, swollen joints and foot pads and airsacculitis. The pathogen is spreading worldwide. Although its mortality is low, it still results in considerable losses due to reduced egg production and meat quality as well as a lowered rate of viable hatchings.A chicken egg farm is threatened by Mycoplasma synoviae infection. This study established a PCR detecting method for propagation research on parent chickens, and preliminarily investigated the source of infection. The results were instructive to the egg farm for preventing the disease from spreading. The main results are as follows:1. The establishment of a high-sensitivity PCR detection method; for parent flock, from 1-day-old a tracking experiment was set: we collected serum, throat swabs and rectal swabs every two weeks from same 50 chickens. Then we detected pathogens by PCR method and serum antibodies with ELISA. Law of Mycoplasma synovial propagation in flocks was revealed: there was no pathogen in swabs and serum in 1-day-old chickens, but their maternal antibodies were high; during the first 6 weeks, MS pathogen were not detected in chickens, the level of maternal antibodies went down to 0, which means the chickens could no longer be protected from infection; in the 8th week, we detected pathogen in throat swab samples, while antibody level elevated which indicated that the chickens were infected; during 10-14 weeks antibody positive rate rise rapidly until the whole group was positive, which showed the rapid spread of MS in chickens; but pathogen were only detected in throat swabs, indicating that the chickens infected through respiratory tract and did not detox through digestive tract.2. We collected environment samples from seven points in hatchery and 6 points in the farm(every two weeks before and after the chickens were fed in it). Negative results indicate that chickens did not infect MS from the environment pollution. Every batch of all live vaccines for the chickens was taken for exogenous pathogen detection. No MS-positive vaccine was found, which means it is not MS-infected vaccine that brought pathogen to the chickens. Environment pollution from hatchery and farm and live vaccines were excluded from potential origin of infectious Mycoplasma synoviae. According to the propagate law of the pathogen, we inferred that it is vertically transmitted from the last generation.