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What Measures Can be Taken to Keep the Hatchery Free of the Fungus Aspergillus

by 5m Editor
16 May 2008, at 12:00am

Background What is Aspergillosis In what ways does Aspergillus enter the hatchery How can I recognise Aspergillosis in the hatchery

1. What is Aspergillosis

Aspergillosis is a fungal infection of the respiratory tract in young birds, also commonly known as 'brooder pneumonia'. In infected birds, the air sacs and lungs show white to yellow spots or lesions. Infected birds gasp for air and have accelerated breathing. Aspergillosis can also result in severe eye (and even brain) infection, which can appear as a yellow cheesy pellet beneath the eyelid. Increased mortality rates of 5 to 50% may occur within 21 days after the placement of diseased birds.

Figure 1. Aspergillus infected eggs

Day-old chicks with signs of Aspergillosis are infected by the spores of Aspergillus species, among which Aspergillus fumigatus is the most common. The spores of the fungus Aspergillus are like small, dry seeds that can easily be spread by draught or the wind. The spores are found in low numbers throughout the whole environment. Aspergillus spores survive and grow in a wide range of conditions, but especially on organic matter, like egg yolk, cardboard boxes and wood. Growth in the spores is initiated by conditions of high humidity and temperature (37-45 °C). Cycles of high and low humidity optimise the growth of the fungus (mycelium) and the spread of its spores. The hatchery therefore offers the optimum environmental conditions for Aspergillus to thrive.

2. At what ways does Aspergillus enter the hatchery

Aspergillus spores can enter the hatchery either directly via the eggs, or via incoming air.

When the hatchery environment is contaminated by a high level of Aspergillus, the spores can easily enter the air handling unit and ventilation system. The climate, temperature and humidity in ventilation ducts is ideal for the propagation of Aspergillus, especially when organic matter (debris) has accumulated.

The main route into the hatchery for Aspergillus spores however, is usually via contaminated eggs. Aspergillus spores attached to the shell find their way into the albumen and yolk via hairlines or cracks in the shell. The yolk of the egg is an ideal substrate for the growth of Aspergillus and once the spores have entered the eggs, the way to the hatchery is open.

The nests also contain several sources of Aspergillus, including bedding, manure and feed. The nest eggs therefore become contaminated by contact with Aspergillus spores from these sources. Floor eggs also, of course, have a high risk of being heavily contaminated, when the spores enter the egg via hairline and other cracks.

3. How can I recognize Aspergillus in the hatchery

Initially, infection by Aspergillus will be found during the routine analysis of unhatched eggs. Infected eggs show a visible mould on the air cell (figure 1). The risk of a serious bloom of Aspergillus is high when 0.5% of the hatching eggs show clear infection with a visible growth of the fungus. Also, the frequency of embryos dying at about day 16 is higher then expected.

Advice

A. Prevention is of course the first line of action. To prevent Aspergillus infection in the hatchery, we recommend the following measures:

  • use Hatchery Recording Forms to ensure that the origin of eggs is traceable (to receive your free copy of Pas Reform's Hatchery Recording Forms, please complete and return the order form in the Library document Incubation Guide).
  • Do not incubate floor eggs.
  • do not incubate cracked eggs or eggs with hairlines.
  • since Aspergillus thrives well on wooden surfaces, avoid wooden walls, ceilings or surfaces in the hatchery.
  • analyse unhatched eggs on a regular basis - and if infected eggs are found, take measures to trace the sources of Aspergillus (see B).
  • ensure your hatchery sanitation programme is fully maintained on a regular - ideally weekly - basis. If moulds are found, take immediate measures to clean the hatchery (see B).
  • ensure that your hatchery sanitation programme includes the cleaning and disinfection of ventilation ducts.
  • remember that hatchery equipment must be free of all organic matter before disinfection. It makes no sense to disinfect equipment, trays or boxes when debris remains stuck to the surfaces.
B. Cleaning measures to ensure the hatchery is free of Aspergillus

When Aspergillus contaminated eggs are found, the hatchery - including ventilation ducts - should be thoroughly cleaned and disinfected with an effective fungicide. If necessary, ask your supplier for advice on the most effective solution.

In addition, it is important to trace and eliminate the source of the Aspergillus spores, the main source of which is usually found to be at the breeder farm in the (wooden) nestboxes, litter, cardboard boxes and wooden walls or ceilings.

Remember that the spores of Aspergillus species are highly resistant to disinfection, so it is advisable to clean and disinfect the hatchery at the end of each day. Since the temperature and humidity of the hatchery environment stimulate the growth of the fungus Aspergillus, any spores that survive the first round of disinfection will continue to grow and can only be eliminated by repeating your programme of cleaning and disinfection regularly.

References:

Williams C., Aspergillus in the hatchery (Embrex publication).

For further information or advice, please contact the Pas Reform Academy.

May 2008