Short answer: Chronic respiratory disease is a long-running airway infection in chickens, most often linked to Mycoplasma gallisepticum and made much worse by stress, ammonia and mixed flocks. Birds show a cough, noisy breathing and a slow decline in weight or eggs rather than sudden death. Management decides how bad it gets, and follow your vet's advice on any diagnosis, treatment or vaccination.
Key takeaways
- CRD is a slow problem: the damage shows up as lost weight and lost eggs, not sudden deaths.
- Mycoplasma is the usual organism, but stress, ammonia and secondary bacteria decide how far it goes.
- Clean air and dry litter reduce the damage more than any single product.
- Keep records of weight, feed and egg output so you can see the decline early.
- Ask your vet to check the flock and the chick batch record before you assume it is just a cold.
What CRD is and why it lingers
Chronic respiratory disease, usually shortened to CRD, is what farmers call a long, rough cough that never quite goes away. The main organism behind it is Mycoplasma gallisepticum, sometimes called MG, though other bacteria often join in once the airway is damaged.
The thing that catches people out is the timeline. A flock with CRD rarely collapses overnight. Instead, the birds lose a bit of weight each week, the layers lay a few eggs fewer, and the cough is there in the morning and again at dusk. Farmers often wait months before they connect the dots, by which time the flock has already paid the price.
We have heard from farmers who thought their birds were just slow growers, only to find that the same house had been coughing since the second week. The disease does not announce itself in the way that sudden infections do.
The signs to watch for in the house
CRD signs are easy to miss because they are quiet. Walk through the house in the early morning, before the birds are fully active, and listen. Then look at the following:
- Coughing, sneezing and a wet, rattling sound when birds breathe, especially after they have been moved or stressed.
- Watery eyes and some nasal discharge, often on one side of the face first.
- Birds huddled and reluctant to move, with feathers that look rough or ruffled.
- Slower weight gain in broilers and a flock that spreads out unevenly as the weaker birds fall behind.
- In layers, a drop in egg count that does not match the feed, the lighting or the season.
- Sinus swelling in some birds, which overlaps with coryza and needs a vet to tell apart.
The noisy breathing is the sign that matters most. Put your ear close to a bird that is sitting still and count the breaths. A bird with a rattle on every breath is telling you the airway is inflamed.
Why stress decides how bad it gets
Mycoplasma can be present in a flock without causing much trouble for a while. What tips it over is stress. A flock that is moved, vaccinated in a rush, heat-stressed or crowded will show the cough far sooner than a calm one.
In Ghana we see three stresses come up again and again. The first is heat in the dry season, when birds pant, eat less and breathe faster. The second is the harmattan, when dust hangs in the air and open-sided houses fill with fine particles. The third is the rains, when damp litter releases ammonia and humidity keeps the air heavy in the house.
Ammonia deserves special attention. Wet litter gives off ammonia that burns the airway lining, and once that lining is damaged the birds are far more likely to develop a chronic infection. If you can smell ammonia at bird height, the birds are already in trouble, and it is time to fix the litter before you fix anything else.
How it moves between birds and houses
Mycoplasma spreads through the air, through direct contact, and through eggs in some cases. A carrier bird can shed the organism for a long period, and a healthy-looking bird can carry it into a flock. That is why we are cautious about mixing flocks and why we tell customers to be careful with birds from unknown sources.
Equipment, people and vehicles also move the bacteria. Feeders and drinkers that go from a sick house to a clean one without washing, a worker who goes between pens without changing boots, and a delivery van that visits several farms can all carry it. Our biosecurity guide sets out the zones and footbaths we recommend, and the same routine helps with CRD.
What the decline looks like week by week
The table below shows the sort of pattern we tend to hear about from broiler farms. Your own numbers will differ, and your vet should look at the actual birds. Use it as a prompt to check your records.
| Week in the flock | What you might notice | What to check |
|---|---|---|
| Week 3 to 4 | Occasional sneeze, a few birds slower to feed | Litter dryness, ventilation, chick batch record |
| Week 5 to 6 | Cough in the morning, weight a little behind the target | Ammonia, stocking density, water intake |
| Week 7 to 8 | Uneven flock, some birds clearly lagging, rattling breath | Weigh a sample of birds, check feed and drinkers, call the vet |
| After week 8 | Persistent cough, poor feed conversion, higher culls | Vet examination, review of the whole management record |
In layers, the same logic applies to the egg tray. A count that stays low for two weeks after feed and lighting are fixed is a flag worth taking seriously.
The management side that makes the biggest difference
There is no quick fix for CRD in the house. What you can control is the environment, and that is where most of the work lies. These are the points we push hardest:
- Dry litter, every day. Remove the wet patches, add fresh material where needed, and check the corners where birds huddle.
- Good air at bird height. Open curtains in the morning, close them when the wind is cold at night, and keep the air moving without creating draughts across the birds.
- Realistic stocking. Crowding raises stress and ammonia. A house that is too full will show CRD sooner than one that is not.
- Calm handling. Move birds slowly, avoid chasing them, and plan vaccinations for a quiet day rather than a busy one.
- Clean drinkers. Birds that drink from slimy water take in more bacteria and more stress.
Feed matters too. A sudden change of feed, a batch that has gone mouldy in the store, or a ration that is short on energy can all make birds more vulnerable. Keep the feed store dry and avoid changing feed in the middle of a respiratory problem unless your vet suggests it.
Why a proper diagnosis matters
CRD is easy to guess and hard to be sure about. Cough and noisy breathing can come from several causes, including infectious bronchitis, coryza, ammonia damage, dust and plain cold. Treating the wrong thing wastes money and time, and it can hide the true problem for weeks.
Your vet can look at live birds, examine a few dead ones if you have them, and in some cases send samples to a laboratory. Ask them to check the flock history, the vaccination record and the house conditions as well as the birds. Bring the records you have kept, including weights, feed intake and egg counts. Those numbers often tell the story faster than the birds do.
Vaccination and the chick batch record
Vaccines are available for some mycoplasma strains, and they are used in breeding and layer flocks in many places. Whether a vaccine suits your flock is for your vet to decide. A vaccine helps reduce the risk and severity of disease, but it does not protect a flock kept in damp, dusty or crowded conditions.
As a typical example only, a layer flock might have a vaccine planned before the birds reach point of lay, with the timing set by the vet and the product. Follow your vet's advice on age, dosing and any booster. Our chicks are vaccinated at the hatchery against Marek's, Newcastle, Gumboro, infectious bronchitis and coccidiosis, and each batch comes with a record. That record shows what the birds have already had, but it does not cover mycoplasma, so your vet needs to plan that part with you.
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What we tell farmers who call us about CRD
Most calls about CRD come from farmers who have already been battling the cough for weeks. The first question we ask is whether the flock is mixed in age or came from more than one source. The second is about the house in the morning: is it smoky, damp or dusty? Only after those answers do we talk about the birds themselves.
We also ask for the batch record and the date the chicks arrived. A chick that came in healthy and was kept in a dry, well-ventilated brooder usually has a much better start. If you are planning a new flock, our brooder setup guide shows the preparation we would want to see before the chicks arrive, and our transport article covers how to avoid stress on the journey.
A CRD control checklist
Work through this list each week. If you cannot tick off most of it, that is the place to start, whatever the vet finds.
- Listen to the house at first light and count any birds with a rattle on each breath.
- Check litter in the corners and under drinkers, and replace wet material.
- Smell the air at bird height for ammonia, and fix ventilation if you can.
- Weigh a sample of birds each week and compare with the target for their age.
- Record egg counts for layers, and note any change in feed or water intake.
- Check that drinkers are clean and that water is not sitting on the floor.
- Keep the feed store dry and remove any mouldy bags.
- Keep new birds apart from the main flock until your vet has checked them.
- Call your vet if the cough lasts more than a few days or the weights fall behind for two weeks.
If you are keeping your first flock
Beginners often think CRD is something that happens to other people's farms. In practice, it is one of the most common reasons a first flock disappoints. The birds grow slowly, the eggs come late, and the farmer cannot quite say why.
The simple answer is that a new farmer rarely has the air, litter and stocking right in the first season. Plan the house before the birds arrive, measure the space, keep the numbers and talk to a vet early. Our starter budget guide covers the costs of building a suitable house, so that you can plan ventilation and litter from the start rather than fixing them after the cough appears.
Keeping CRD from taking your margin
CRD is not a disease you beat with one good week. It is a disease that the house either allows or stops, day after day. Keep the litter dry, the air clean, the birds calm and the records honest, and most flocks run much better.
If you want to talk through your house, WhatsApp us on +233 24 915 1503. We are happy to talk about the chicks, the breed and the setup. Our broiler page and layer page show the options we hatch, and when you are ready you can use the order form. We confirm the price in writing before any payment is made. Questions about the hatchery itself are answered on our about page, and the usual questions about delivery and chick health are collected in the FAQ. If you are planning a larger order, our bulk page explains how we quote bigger numbers.
Questions farmers ask
Is CRD the same as bird flu?
No. CRD is a chronic respiratory infection that is usually caused by mycoplasma and worsened by other factors. Avian influenza is a different and much more serious virus. If you see sudden high death rates, report them to your vet straight away rather than assuming it is CRD.
Can CRD be cured?
Mycoplasma infections are difficult to clear completely from a flock. Birds can carry the organism for life, so the goal is usually to reduce the damage, keep birds comfortable and protect production. Follow your vet's advice on whether any treatment is worth using in your case.
Why do my birds cough only in the morning?
Birds often cough more when they wake up, when the air in the house is at its most stale and when ammonia has built up overnight. A morning cough that clears as the house airs out points to ventilation and litter as the first things to fix.
Can CRD spread to people?
Mycoplasma gallisepticum is a bird pathogen and is not generally considered a risk to people in the way some other poultry diseases are. Still, wash your hands after handling sick birds and keep your dust exposure low. Ask your vet if you have specific concerns.
How long does CRD take to show after stress?
It varies, but a stress event such as a move, heat wave or harmattan storm can bring out the signs within days in a flock that already carries the organism. That is why we recommend keeping stress low during the first weeks and during the weather changes.
Does feeding more protein help?
Good nutrition helps the birds resist disease, but more protein does not cure CRD. A balanced ration, clean water and dry litter matter more than any single nutrient. Talk to your vet or feed supplier before changing a ration in the middle of a respiratory problem.
Will my eggs be safe to sell if the flock has CRD?
Eggs from birds with mild respiratory disease are usually still fit to eat when properly cleaned and stored, but the output drop is the bigger issue for most farms. Follow your vet's advice on hygiene and on any withdrawal periods that apply to any medicine you were given.
