Gumboro (IBD) in broilers: ages, signs and vaccine questions

Gumboro, also called infectious bursal disease or IBD, attacks the bursa, the organ where young chickens build their immune system. It usually strikes broilers at about 3 to 6 weeks of age. Even when few birds die, Gumboro leaves the flock weak against other diseases and with a worse FCR, so the goal is to prevent it: the right vaccine at the right time, planned with your vet, and very strong cleaning between batches.

What Gumboro does to the bird

The bursa of Fabricius is a small organ near the vent. In a young bird it trains the cells that make antibodies. The Gumboro virus destroys these cells. A bird that survives Gumboro has a damaged bursa, so it responds poorly to other vaccines, such as Newcastle, and catches E. coli and breathing infections more easily.

This is why Gumboro is costly even when deaths are low. The batch may grow slower, eat more feed per kg of weight and suffer more from the next problem that comes along.

Ages at risk

• First 2 to 3 weeks: chicks usually still carry antibodies from the parent flock. If the virus gets in now, there may be no clear signs, but the bursa can still be damaged. This hidden (subclinical) form shows up later as poor growth and vaccine failures.
• About 3 to 6 weeks: the classic disease, with visible signs and deaths. Most outbreaks in broilers fall here.
• Later: less common in broilers, but possible.

Signs in the shed

Signs usually start 3 to 4 days after infection, and often come on suddenly:

• Birds dull, sitting with ruffled feathers, huddled together.
• Whitish, watery droppings and dirty, wet feathers under the vent.
• Some birds pecking at their own vent.
• Trembling, staggering, birds not wanting to move.
• Feed and water intake falling, birds becoming dehydrated.
• Deaths rising for a few days, peaking, and then usually falling within about a week.

When a vet opens a dead bird early in the outbreak, the bursa is often swollen, yellowish and sometimes bloody. Very strong strains can also cause bleeding in the thigh and breast muscles. Later, the bursa shrinks. Lab tests confirm the diagnosis.

Vaccine timing: the questions to ask

Gumboro vaccination is harder to time than most. If a live vaccine is given while the chicks still have high antibodies from the mother, those antibodies can block it. If it is given too late, the field virus can get in first. Your vet balances these. Ask:

1. What did the hatchery give? Some chicks get a vector or immune-complex Gumboro vaccine at the hatchery. If so, a separate live Gumboro vaccine may not be needed, or the plan changes. Ask the hatchery for this in writing with each delivery.
2. How strong are the maternal antibodies? Parent flocks are usually vaccinated so chicks start with protection. Some vets test a few chicks' blood at day one to estimate the best vaccine day.
3. Which strain of vaccine suits our area? Vaccines differ in strength. In areas with very strong field virus, a vet may choose a stronger vaccine or a different plan.
4. One dose or two? Depending on the chicks, some plans use one live dose, others two, a week or so apart. Do not change this on your own.
5. Which route? Most live Gumboro vaccines go in drinking water. Ask about water quality, stabiliser and how long the birds should take to drink it.

Our broiler vaccination schedule guide shows how Gumboro fits around Newcastle and other vaccines, and how to keep the vaccine cold.

Hygiene: the virus stays on your farm

The Gumboro virus is very tough. It survives a long time in litter, dust and cracks in the shed, and many common disinfectants do not kill it well. Once a farm has had Gumboro, the next batch is at higher risk unless cleaning is serious.

Between batches:

• Remove all old litter and take it well away from the shed. Do not spread it in fields next to the farm.
• Dry clean first: sweep dust from walls, roof, beams, fans and curtains.
• Wash with water and detergent, including feeders, drinkers and water tanks.
• Disinfect with a product your vet recommends for tough viruses, at the strength on the label.
• Leave the shed empty and dry for as long as you can before new chicks.
• Put in fresh, dry litter. See litter management for material and depth.

During the batch: control visitors, use foot dips, keep crates and trucks away, and never bring birds of a different age onto the farm.

If Gumboro hits your flock

1. Call your vet and send fresh dead birds for testing.
2. Keep water clean and available. Weak birds may need drinkers closer to them.
3. Keep the shed comfortable: no cold drafts in winter, no heat build-up in summer. Stress makes it worse.
4. Remove dead birds several times a day and dispose of them properly.
5. Follow your vet's advice on any treatment for secondary infections.
6. Write down the day signs started, daily deaths and what was given.

After the batch, expect a worse FCR than usual and compare it with earlier batches in the FCR calculator. Tell your vet the full story so the next vaccine plan can be adjusted. Watch the next batches closely for signs of Newcastle too, since Gumboro-weakened birds are more at risk; see Newcastle disease (Ranikhet).

Keeping every batch's vaccine dates, hatchery details and FCR in Poultry Curve makes this kind of pattern easy to spot. You can also ask Helper to compare batches, then take the answer to your vet.