[The effect of Mycoplasma synoviae infection on the state of health and results of fattening of broiler chickens compared with the effects of various virus infections. A field study (author's transl)].

Field studies in 160 flocks of broiler chickens in two areas in the Netherlands showed that Mycoplasma synoviae infection, the presence of which was detected by serological testing in 17.5 per cent, had only a slight adverse effect on the results of fattening. Mycoplasma synoviae as well as IB infections were found to be more common in flocks affected with colibacillosis and/or in which higher proportions of birds were condemned because of polyserositis. Infectious bursal disease, IB and CELO virus infections are very common particularly in the southern areas of the Netherlands, and have a significantly adverse effect on the results of fattening. The findings suggest that vaccination against IB and Gumboro disease often fails in flocks in areas showing a high incidence of infection.