Investigation of novel strategies to control Campylobacter in commercial broiler flocks

Campylobacter is the most common cause of bacterial food poisoning in the world. Campylobacteriosis is generally mild and self-limiting, typically characterised by 1-3 days of fever, followed by 3-7 days of abdominal cramping and bloody or watery diarrhoea, however, in a minor number of cases Campylobacter can be a precursor to a number of more serious illnesses such as Guillian-Barré syndrome (GBS) or Miller Fisher syndrome (MFS). Broilers are a natural host for Campylobacter with poultry accounting for an estimated 50 – 80% of campylobacteriosis cases. In 2018, it was found that 26% of broilers and 72% of turkeys within the European Union (EU) were colonised with Campylobacter. Therefore, it has been suggested that reducing Campylobacter carriage in broilers by 2-3 log10 could result in a 76 – 100% reduction in campylobacteriosis cases, and so, extensive research has been carried out to eliminate Campylobacter at farm level. The aims of this project were to investigate novel strategies that could be implemented for use in the control of Campylobacter in commercial Irish broiler flocks such as enhanced biosecurity and the use of natural feed/water additives, and to investigate the effects of feed and antibiotic use on the broiler microbiome throughout the broiler rearing period. It was found that enhanced biosecurity through the use of a biosecurity framework consisting of biosecurity pens presents a potential solution to prevent broiler colonisation by campylobacters while also increasing productivity up to 20% by limiting contact between broilers and farm staff and sub-dividing broilers into smaller flocks while maintaining the same stocking density. OA, EO, and MCFA based treatments were found to show great potential as anti-Campylobacter additives when tested in vitro, however when tested in vivo, these compounds had a negative impact on broiler performance, significantly impacting the caecal microbiota, casting doubt on their effectiveness within the broiler industry. In vitro broiler feed digestates were found to be incapable of supporting Campylobacter growth and so it was concluded that the nutrients available in the feed digestates capable of supporting C. jejuni growth and additional factors may be at play in the avian gastrointestinal tract potentially explaining Campylobacter’s affinity towards the broiler GIT. The microbiota in the broiler GIT was found to be influenced by the age of the birds, the location within the GIT, and antibiotic treatment. With major changes observed in the broiler microbiota as the birds aged and antibiotic treatment in early life significantly altering the microbiota throughout the remainder of the rearing period. It was therefore concluded that: • Enhanced biosecurity shows great potential for the reduction and possible elimination of Campylobacter from commercial broiler flocks, and the implementation of a biosecurity framework could both reduce colonisation of broilers while increasing productivity. • Natural OA, EO, and MCFA based water additives were promising anti-Campylobacter water additives in vitro, however, these results do not transfer well in vivo and highlight the need for further research into their development. • Broiler aging and antibiotic therapy both cause significant changes in the broiler microbiota providing a potential explanation for the delayed Campylobacter colonisation seen in broilers, while the microbiota shifts associated with antibiotic therapy could impact broiler performance.2022-10-03 JG: Author's signature removed from PD