Aspergillosis in Chicks: Brooder Pneumonia and How to Stop It

Listen to the brooder at dusk

Stand outside the brooder at dusk for a minute, with the lights low and the chicks settling. In a healthy brood you hear soft peeping and the odd scuffle. In a brood with aspergillosis you may hear thin, wheezy breathing, and see a few chicks standing apart with their beaks open and their necks stretched. Farmers describe it to us as chicks that are breathing with their mouths.

Aspergillosis, often called brooder pneumonia, is a fungal disease of the lungs and air sacs. It is caused mainly by Aspergillus fumigatus, a mould that grows on damp organic material and releases huge numbers of tiny spores into the air. The chick breathes the spores in, they settle in the lungs and air sacs, and they grow there.

It is mostly a young bird's disease. A chick's lungs are small and its defences are still developing, so a dose of spores that an older bird would shrug off can overwhelm a chick in its first two or three weeks. Deaths tend to cluster early, which is when many farms feel the loss most.

Where the spores come from

Aspergillus is a normal part of the environment, and nobody can remove every spore from a farm. The trouble starts when a place becomes wet, warm and full of organic material. The mould then grows and releases spores faster than the chicks can cope. Find the source and you have found most of the problem.

Rice husk and sawdust deserve a special mention. Both are cheap, both are common across the country, and both are often stored in conditions that encourage mould. A bag that smelled fine when it was bought can be musty after a month in a damp corner of a shed.

What the chick looks like

Signs appear in stages, and the early ones are easy to miss because they look like chilling or a bit of stress. Look for several of these together, not one on its own.

• Open-mouth breathing, with the beak parted and the neck stretched while the chick is at rest.
• Gasping or wheezing, and breathing that gets faster after the chick is moved.
• Lethargy, with birds sitting apart from the group and not coming to the feeder.
• Weight loss and a dull, ruffled look that does not improve with warmth.
• Sudden deaths in the brooder, often in birds that were eating the day before.

Older birds can get it as well, usually where they have been exposed to a heavy mould load in a poorly kept house or a store of damp feed. The signs are similar, but the course is often slower, and more birds may be affected before anyone notices. Other reasons chicks die in the first weeks are sorted out in our piece on common chick diseases.

What the lungs and air sacs show

A post-mortem gives you the most useful look you can get. Ask your vet to open a fresh bird from the sick group. Aspergillosis is often recognised by greyish or yellow-white patches, or small raised nodules, on the lungs and on the air sac membranes. In a bad case the lung tissue is firm and the air sacs look cloudy and thickened.

Those findings point towards a fungal cause, but they do not tell the whole story on their own. Your vet may send tissue to a laboratory for culture, and will compare the findings with the house. The conditions in the brooder matter as much as the lesions, so describe the bedding, the feed storage and the rain in the week before the chicks got sick.

Do not open a bird and decide for yourself. A bird opened carelessly can release spores into the air around you. Handle any post-mortem outdoors or somewhere well ventilated, and wear a mask.

The hatchery end of the problem

Some chicks start life with spores already around them. A chick that hatches from a dirty setter or hatcher breathes in mould from its first hour, and a weak chick from a poorly managed hatch has less ability to clear it. We cannot control your brooder, but we work hard on hatch hygiene and transport, because a chick that starts clean has a better chance against anything in the air.

On the incubator side the rules are simple. Clean and dry the setter and hatcher between hatches, remove broken and mouldy eggs at once, and keep the water trays clean. Our article on cleaning and disinfecting an incubator shows the routine. If you buy hatching eggs, store them somewhere dry and clean, because moisture on the shell is an open invitation to mould.

A chick that arrives in a damp box, or a box that spent hours in a hot, stuffy vehicle, has also had its airways irritated. That irritation makes the next step easier for the fungus. Check the box on arrival and move the chicks straight to a dry, warm brooder.

Bedding and the rice husk problem

Bedding is where most farms win or lose this fight. Good bedding is dry, absorbent and low in dust. Shavings from a timber yard, dry rice husk, chopped straw and sawdust all work well when they are fresh and kept dry. They all turn into mould when they get wet and sit.

Dry bedding feels light and loose under your hand and has a neutral, woody or grassy smell. Wet or mouldy bedding is dark, clumps when you squeeze it and gives off a sweet, rotten smell. If you find the second kind, throw it out, clean the brooder, dry it for at least a day, and lay fresh material at a depth you can keep dry. A thin, damp layer is worse than a deeper, dry one.

Store bedding on a pallet or raised platform, under a roof, and away from walls where rain runs in. A bag stacked against a damp wall in the rainy season can grow mould within a few weeks, and the first sign is usually a patch of dust on the sack, not a bad smell. Keeping litter dry once the birds are older is a related job, covered in our broiler litter management article.

Warm and dry, not warm and damp

Chicks need heat, and the brooder has to supply it. The trouble comes when heat and moisture rise together. Warm air holds more moisture, and a brooder shut tight to keep the heat in can turn into a humid box where mould thrives and spores hang in the air.

The fix is ventilation without draught. Chicks should not sit in a stream of cold air, but the air in the brooder should move enough to carry moisture out. Keep the ring or guard at a size that gives the chicks room to move, and check that the litter under the heat source stays dry. Our guide to setting up a brooder ring shows the layout, and our brooder temperature chart explains how to read the chicks' behaviour.

Power cuts add a twist. When the heat source stops, the brooder cools and chicks pile into a corner, sometimes against a damp wall. When the power returns, the brooder can overheat and that corner can sweat. Keep a plan for power cuts, and check the litter each time the heat comes back on. Our note on heat sources for brooding compares the options.

Feed storage and the mould you cannot see

Feed is the second big source. Mould in feed often hides under the top layer of a bag or sack, and a chick that pecks at a dusty corner takes a dose. Spoiled feed is also why some farms see deaths rise after a delivery that sat out in the rain.

1. Store feed on pallets, off the floor and away from walls.
2. Use the oldest stock first, and write the delivery date on each sack.
3. Check the top and the bottom of every sack for clumps, grey dust or a musty smell.
4. Replace any feed that got wet, even if it dries out later.

Mould in feed also brings toxins, which are a separate problem covered in our article on feed storage and aflatoxin. Spores and toxins come from the same mould, so manage both at the same time.

Treatment is a vet decision

There is no product in the shop that you should reach for at the first sign of breathing trouble. Antifungal treatments exist, but they are used under a vet's direction, because the choice depends on the cause, the age of the birds and how far the disease has gone. Many badly affected chicks do not recover, and a poorly chosen product adds residue risk to birds you may sell later.

What your vet will focus on is fixing the environment, because that is what stops the next batch from getting sick. They may also advise on supporting the birds with clean water and easy-to-digest feed while the problem is dealt with. Follow your vet's advice on any product, its timing and its withdrawal period.

Remove the sick birds from the brooder as far as you can without stressing the rest. Keep their bedding and feed separate, and wash your hands and change footwear between handling sick chicks and healthy ones.

A brooder hygiene checklist

Print this, pin it inside the brooder door and tick it off before every batch. The first two days have their own routine, set out in our first 48 hours with new chicks guide.

1. Check the bedding for a mould smell and dust before the chicks go in.
2. Store bedding and feed on raised platforms, under cover and away from damp walls.
3. Clean and dry the brooder between batches, and let it stand dry for at least a day.
4. Remove wet or caked bedding every day, not only when the chicks look poorly.
5. Keep ventilation open enough to clear moisture and dust, without a draught on the chicks.
6. Check the feed for clumps and a musty smell every time you open a bag.
7. Note any chick breathing with its mouth open, and call your vet that same day.

What we check before chicks leave

Our side of the fight is clean hatching, careful handling and dry, ventilated boxes on the way out. Chicks leave the hatchery the day they hatch, so there is no long wait in a warm store where mould can build up. If a box arrives damp, hot or stuffy, tell us the same day with a photo, and we will look at what happened on the road.

We cannot promise that a chick will never meet mould on your farm, and we would be misleading you if we said so. What we can do is send you clean, lively chicks and help you think through the brooder. If the first week is going badly, message us on WhatsApp at +233 24 915 1503 and we will talk it through. Our day-old chicks page explains the process from hatch to delivery, and the delivery page covers the road side.

Questions farmers ask