Serological studies on flocks showing depressed egg production

Area of Science:

• Avian pathology
• Virology
• Poultry health

Background:

• Poultry flocks experiencing reduced egg production present a significant economic challenge.
• Previous investigations ruled out common pathogens like adenovirus, infectious bronchitis virus, and Mycoplasma species.

Purpose of the Study:

• To identify the etiological agent responsible for depressed egg production in poultry.
• To investigate the serological evidence of viral infections in affected flocks.

Main Methods:

• Serological investigation of poultry flocks with reduced egg production.
• Antibody testing against various avian viruses and Mycoplasma species.
• Retrospective survey of fowl sera for antibody to a specific haemagglutinating virus (127).

Main Results:

• No correlation found between depressed egg production and antibodies to adenovirus, infectious bronchitis virus, or infectious bursal disease virus.
• Antibodies to Newcastle disease virus, Mycoplasma gallisepticum, and Mycoplasma synoviae were largely absent.
• A significant association was identified between antibodies to the haemagglutinating virus 127 and depressed egg production.
• The first detection of antibodies to virus 127 in Northern Ireland was in June 1976.

Conclusions:

• Virus 127 is strongly implicated as the cause of depressed egg production syndrome in poultry.
• Limited lateral spread suggests vertical transmission or vaccine contamination as primary dissemination routes.
• Widespread European occurrence, despite poor horizontal transmissibility, supports the hypothesis of vaccine contamination with virus 127.