How does early microbiome modification affect immune response in broiler chickens?

Chickens are the most frequently reared livestock, with in excess of 60 billion birds reared globally each year in a range of production systems. In intensive commercial systems, vaccination is a key tool in the control of infectious diseases. Increasing evidence shows a link between the gut microbiome and the development of the immune system. Commercially produced chickens are frequently raised in hatcheries, where they are unable to acquire a ‘normal’ microbiome maternally, and are instead colonised by bacterial species from the hatchery environment. As a result, these birds may have impaired immune development, potentially rendering them susceptible to infection. By transplanting a healthy adult microbiome at hatch, we investigated the effect of early microbiome-based intervention on colonisation and immune response to two different Salmonella serovars. We then looked at differences in response to a parenterally administered inactivated Salmonella Typhimurium vaccine, and an orally administered live attenuated Salmonella Typhimurium vaccine. Finally, we looked at differences in intraepithelial lymphocytes, and splenic T-cell populations.