First line of defence for bird health

At the time of going to press, there have been several HPAI outbreaks in commercial facilities across Europe – with the most recent outbreaks in the UK, Germany and the Netherlands. This and other pathogens demand good biosecurity, as well as a second line of defence: the birds’ immune system.


ighly virulent diseases like these are rising in preva lence, especially in regions where previously these diseases were rare. Global warming is undoubtedly playing a part; shifting migratory

bird patterns and milder winters are allowing pathogens and their host species to survive where previously they might not have. Biosecurity can be considered the first line of defence against pathogens. A good, well-managed programme can prevent nearly every infection from reaching birds. Often, people are considered the greatest biosecurity risk to a flock, but any external object brought in from outside the shed en- vironment should be viewed as a risk. Should biosecurity fail and a pathogen enters the shed, the next line of defence is the bird’s immune system. Different pathogens will each have a different impact on a bird. The manner in which birds respond to challenges and the knock-on performance de- cline, will depend on a number of factors. Genetics play a major role, alongside nutrition and the microbiota.

Entry for pathogens The gastrointestinal and respiratory tracts are often the main points of entry for pathogens. Maintaining general bird and immune system health is critical to giving birds the best chance of fighting off infections without seeing morbidity. Overall, 70% of the immune system functions in some way through the gut tissue. Therefore, improving gut health is critical to supporting immunity. The gut is an ecosystem com- posed of a plethora of micro-organisms. This microbiota, if

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balanced and diverse, can help to modulate or ‘educate’ the naïve immune cells, allowing them to learn what is a real threat and how to respond to that threat. The microbiota also interact directly with the epithelial cells lining the gut wall and have a role in modulating the inflammatory pathway. Excess mucus is an output of the inflammatory pathway and acts as a barrier to prevent pathogens from attaching to the cells of the gut lining. However, excessive mucus production also acts as a barrier preventing nutrients from being ab- sorbed as easily and, as a result, has a major impact on feed conversion. While mucus production is necessary for the prevention of pathogenic attachment, overproduction has a significant effect on performance. As such, the role of the micro biota in immune system modulation should be at the forefront of producers’ minds. Ensuring diversity in the micro- biota will allow the immune system to function at optimum level while reducing disruption to performance. This is a huge contributing factor in helping birds to fight off potential pathogens.


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