Immunity is ability to stop an infection. Immunosupression is a status where
the immunity is reduced. Humoral (antibodies) and/or cell immunity may be
depressed. Immunosupression can be caused by infectious agents, improper
feeding balance (deficiencies), lack of biosecurity, management failures,
stress or by a combination of these factors. Each of these possible causes
must be seriously worked out to prevent the consequences of immunosupression
on profitability. Environmental factors and numerous infectious pathogens
have been identified as a multi-factorial cause of various degrees of
immunosupression. Mainly subclinical character and coinfections make the
diagnosis of the primary immunosuppressive agents difficult. On the other
hand, early diagnosis and identification of contributing factors are
important to develop strategies to fight immunosupression in birds
successfully. A combination of biosecurity measures, optimized housing
condition and stress reduction together with appropriate vaccination
strategies is necessary for the successful control of immunosupression in
commercial poultry.