What is Aspergillus? (commonly called “Aspi”)
Aspergillus is a widely occurring fungus which is commonly found as a pathogenic organism in the chicken industry. Aspergillus Fumigatus, in particular, is one of the main respiratory pathogens in the industry and is found in hatcheries and chicken houses. If uncontrolled, it can be responsible for high mortalities and subsequent large financial losses to the farmer.
Aspergillus Fumigatus is a common naturally occurring fungus. It can occur anywhere, depending on suitable ambient conditions. It is present in the air, grass (hay), wild birds and anything used as bedding litter. It is a vigorous grower and will proliferate rapidly in any suitable organic material. This results in massive amounts of spores (conidia) which are easily carried by wind or spread by dirt. In chickens (and also humans) these spores can be inhaled and become deposited in the respiratory tract where they grow and cause aspergillosis. This aspergillosis can cause high mortality in chicks, and can affect the immune system of mature birds adversely.
The impact of Aspergillosis on chicks and embryos
- Increased embryo mortality results in decreased hatchability
- High chick mortality rate due to pneumonia in chicks
- Early chick mortality of between 20% to 50%
- Reduced viability due to immuno-suppression
- Low weight broilers
- Increased mortality during growing out
- Secondary infection in chicks 4 to 5 weeks old
- Increases infection control costs
- Poor quality chicks
How is Aspergillus detected?
- The presence of Aspergillus can be detected by surface swabbing and sedimentation plates.
- These are then incubated under controlled conditions and the presence of spores detected by the subsequent growth of distinct fungal colonies.
Where do Aspergillus Fumgatus infections originate?
- On farms the most common source of infection is contaminated litter, or dust blown spores from the environment.
- In hatcheries, dirty incoming eggs can introduce an infection. Poorly managed and insufficiently disinfected hatcheries may become a reservoir of infection in the setters/hatchers, which will increase the chances of further contamination of new clean eggs.
- Contaminated day old chick fluff can also cause the massive infection of other day old chicks in the hatchers themselves. These chicks will then develop full blown symptoms in the farms after transfer.
What conditions favour the proliferation of Aspergillus?
Ideally, high humidity and temperature, and the presence of organic material such as shavings, cracked eggs, down, and feathers. All these can be found in the chicken industry.
What preventative measures can be implemented to reduce the impact of Aspergillus in the chicken industry?
- Manage feedstuffs and litter by keeping it as dry as possible. This will result in low humidity levels which will reduce the growth potential of fungus.
- Good ventilation practices are essential together with regular humidity monitoring.
- Dust levels should be limited as much as possible to prevent the spread of spores.
- The implementation of a structured anti-fungal programme at all levels of the industry. This should involve the spraying of litter, and regular thermal fogging egg trucks and hatcheries, including air ducting, setters, egg rooms, and hatchers. Products containing Imazalil have been previously used with great success.
Ignoring the threat of Aspergillus
- Reduce profitability
- Lower product quality
- Put your business at risk