EN
Mycoplasmosis avium is a highly infectious disease, which has been diagnosed mainly on commercial poultry farms. It usually occurs in meat-type flocks of hens, turkeys, and also in ducks and geese. The purpose of the study was to define the level of dissemination of infections caused by mycoplasmas in flocks of reproduction meat-type hens and broilers. The experiment covered 142 reproduction meat-type flocks (1 day - 65 week-old birds) and 136 broiler flocks (1-7 weeks old birds). The materials used in the studies were blood samples collected from the farm birds in 1998-1999 (until August). Blood samples were collected once in layers and in 109 broiler flocks, and twice in the other 27 broiler flocks, i.e. in one-day chicks and in the 6,h week of rearing. Moreover, additional 15 broiler farms were included in the serological monitoring (tests performed on 1st day, 2nd - 3rd and 6,h - 7th week of rearing). The level of M. gallisepticum and M. synoviae antibodies in serum was determined by ELISA (Idexx kit with MG/MS antigen) and additionally by RPA test (MG and MS antigen by Intervet) on 15 farms. The presence of specific Mycoplasma antibodies was found in 54.9% of the layer flocks monitored. However, the highest percentage of serologically positive flocks was recorded in the laying period (65.2%) and the lowest in one-day old chickens (30.8%). Infection with Mycoplasmosis in broilers reached 44.1%, and in these cases the occurrence of MG/MS antibodies was observed more often in one-day old chicks (55.1%) than in 6- -7 week old chickens (32.1%). The flocks of broilers demonstrated more infections with M. synoviae than with M. gallisepticum (25.9% and 7.4%, respectively in the 6th week).