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Most winter broiler batches look fine until day 15. The chicks are out of the brooder, eating well, and the farmer relaxes. Then, in the third and fourth week, the shed starts to smell, the litter near the drinkers turns into a wet cake, birds start sneezing at night, and in the last week the heaviest birds die with a swollen, watery belly. None of this is bad luck. It is what happens when a closed winter shed holds heat but not fresh air. This guide covers the second half of the batch, from day 15 to sale: how much air to give at each age, how to read ammonia with your own nose and eyes, how to work the curtains through the day, and what targets to aim for every week. For the first two weeks, read our winter broiler brooding guide first.

In short: after day 15, birds need less heat and more air every week. Keep them warm at bird level, but never seal the shed. If your eyes burn or you smell ammonia when you bend down to bird height, the shed needs more fresh air, even on a cold night.

Why winter batches lose money after day 15

In the first two weeks, chicks are small, they breathe little and they produce little moisture. By day 21 the same flock eats several times more feed, drinks several times more water and puts out a lot of moisture through breath and droppings. If the curtains are still closed the way they were in week one, that moisture has nowhere to go. Five problems follow, and they feed each other:

ProblemWhat you seeHow it costs you
Ammonia build-upSharp smell, eye burning, birds with watery eyesDamages the airways, birds eat less, opens the door to CRD and E. coli
Wet, caked litterSticky cake under drinkers, dirty feathers, breast and foot soresMore ammonia, more coccidiosis, downgraded birds at sale
CRD / E. coli (respiratory complex)Rattling sound at night, sneezing, swollen face, rising deaths in week 4–5Poor weight, poor FCR, medicine cost, culls
Ascites and sudden death (SDS)Blue comb, swollen water belly, heavy birds found dead on their backYou lose the biggest birds, right before sale
Low water intakeIce-cold water in the morning, slow drinking, dry feed left in feedersLess feed eaten, slower growth, uneven flock

The good news: almost all of these come from the same root cause, poor air and moisture control, so one good routine fixes most of them together.

Minimum ventilation by age

Think of it this way: heat is for the bird’s body, fresh air is for its lungs. You can give both at the same time. Minimum ventilation means the smallest amount of fresh air that still removes moisture and ammonia, without chilling the birds. It is not “opening the shed”. It is a small, steady exchange of air, every hour, day and night.

Temperature and air guide, day 15 to sale

Age (days)Temperature at bird heightFresh air needWhat to watch
15–21About 26–24 °CSmall but continuous; top curtain gap even at nightMoisture rising fast; first ammonia smell in early morning
22–28About 24–22 °CClearly more than week 3; open more in the warm afternoonCaking near drinkers, first sneezing
29–35About 22–20 °CHigh; birds now make a lot of heat themselvesAmmonia at night, ascites in fast birds
36–saleAbout 20–18 °CHighest of the batch; heavy birds can overheat even in winterPanting in the afternoon, sudden deaths, wet litter

These are general figures. Follow your chick company’s breed chart and your vet’s advice for your shed, because shed design and local weather differ a lot. Always measure at bird height, not at your head height, and keep at least two thermometers in different parts of the shed.

Sheds with fans (EC or tunnel)

If you have exhaust fans, use a timer for minimum ventilation instead of keeping all fans off at night. A common starting point is to run one fan for a short time in every few minutes (for example, under a minute in every 5 minutes) and increase the run time as the birds grow and whenever you smell ammonia. Your air inlet must be small and high, so cold air mixes near the roof before it reaches the birds. For more detail, see poultry ventilation management.

How to judge the air without any machine

  • The bend-down test: when you enter in the morning, bend down to bird height for 30 seconds. If you can clearly smell ammonia, it is already above what is comfortable for birds. Aim for no noticeable smell.
  • Eye burning: if your eyes water or sting, ammonia is high and birds are already being hurt. Increase fresh air the same day.
  • Water drops on the roof or curtains in the morning mean moist air is not leaving the shed.
  • Bird behaviour: birds huddled in groups are cold; birds spread with open beaks and wings away from the body are hot; birds spread evenly, eating, drinking and resting, are comfortable.
  • Stuffy, heavy air and headache in workers are a warning, especially where coal or wood heaters are used.

Do the check at the worst time: early morning, before you open anything. That is when ammonia is highest.

Curtain management by time of day

In open-sided sheds, curtains are your ventilation system. The golden rule: open from the top, never from the bottom. Air coming in from the bottom hits the birds directly and chills them; air from the top mixes with warm air first.

TimeCurtain positionWhy
Early morning (before sunrise)Mostly closed, but a small top gap on the side away from the windColdest hours; the gap still lets ammonia and moisture out
Mid-morning (after the sun is up)Open the top gradually, a few inches at a timeFlush out the night’s ammonia as the outside warms up
Afternoon (warmest hours)Open the most of the day; in week 5–6 open widely if birds pantBest chance to dry the litter and change the air
Late afternoon (before sunset)Start closing in steps, not all at onceAvoid a sudden temperature drop as the sun goes down
NightClosed, with a small top gap on the downwind sideNever seal the shed completely, especially from week 3 onward
  • On windy or foggy days, open the side away from the wind and keep the windward side closed.
  • A second inner curtain or a false ceiling of sheet or tarpaulin above the birds keeps warmth in without stopping air exchange near the roof.
  • Check curtains for holes and loose edges. A draught at bird level near a torn curtain chills birds more than a planned top opening.

Heater management after brooding

After day 15, the flock starts to produce its own heat. Heaters move from “always on” to “night and cold spells only”.

  • Reduce step by step. In week 3, heaters usually run mainly at night and in the early morning. By week 4 most flocks only need heat on very cold nights. Let the birds and the thermometer guide you, not the calendar alone.
  • Coal stoves, wood heaters and angithis must have a working chimney or pipe that takes smoke outside. Smoke and carbon monoxide inside a closed shed harm birds and workers. Never keep an open fire in a sealed shed.
  • Gas brooders also use oxygen and release moisture. More heaters means you need a little more fresh air, not less.
  • Keep heaters away from curtains, litter piles and feed bags. Every winter some sheds burn down.
  • Do not turn all heat off on the first warm day. Nights can drop sharply; a cold night in week 4 can trigger a respiratory problem that takes the rest of the batch to recover from.

Litter management, day 15 to sale

Litter is where most winter problems start. Dry, loose litter soaks up droppings and releases little ammonia. Wet, caked litter is a factory for ammonia, coccidia and bacteria. For a full guide to fixing it, read wet litter and loose droppings in broilers in winter.

  • Squeeze test daily: take a handful of litter from three places, including near drinkers, and squeeze. Good litter falls apart when you open your hand. If it stays as a ball, it is too wet.
  • Rake or turn the litter regularly, during the warmest part of the day when curtains are open, so moisture can escape. Start near drinkers and feeders, where caking is worst.
  • Remove caked patches under and around drinkers, take them out of the shed, and fill the spot with fresh dry litter.
  • Add a thin layer of fresh, dry litter (rice husk or wood shavings) on wet areas rather than piling a thick layer on top of wet cake. The wet layer underneath will keep giving off ammonia.
  • Stop the water at the source: set drinkers at bird back height, fix leaking nipples and pipes, and do not overfill bell drinkers. Most wet litter in winter is caused by drinkers, not by disease.
  • Do not spread lime heavily on wet litter while birds are in the shed. It makes dust and can raise ammonia release. Ask your vet before using any litter treatment.

Water in winter: temperature, intake and cleanliness

Water is the most ignored input in winter. A bird that drinks less eats less, and a bird that eats less does not grow.

Water temperature

Water lying in tanks and pipes overnight can be ice cold by morning, and birds drink much less of it. Take the chill off: keep tanks shaded from cold wind, insulate exposed pipes, and flush the lines in the morning so birds get fresher, less cold water. Water at roughly room temperature is fine. Do not give hot water.

How much should they drink?

A healthy broiler flock usually drinks roughly 1.7 to 2 times as much water as feed by weight. In cold weather the ratio often moves to the lower end. A rough daily guide per 1,000 birds:

AgeWater per 1,000 birds per day (rough guide)
Week 3 (day 15–21)About 160–200 litres
Week 4 (day 22–28)About 230–280 litres
Week 5 (day 29–35)About 290–340 litres
Week 6 (day 36–42)About 340–400 litres

The exact number matters less than the trend. Fit a simple water meter, or note how many times the tank is filled. A sudden drop in water use for a day is often the first sign of disease, cold stress or a blocked line, a day or two before you see sick birds.

Sanitising water

  • Clean tanks and flush drinker lines between batches; biofilm in pipes grows E. coli.
  • During the batch, use a water sanitiser at the dose advised by your vet.
  • Stop sanitisers on vaccination days and while giving probiotics or other water products that should not be mixed, as your vet or the label says.

More on this in water quality for poultry.

Feed and energy needs in cold weather

In cold weather, birds use part of their feed just to stay warm. If the shed is too cold, feed is burnt as heat, not turned into meat, and FCR gets worse. So warmth at bird level is also a feed-saving measure.

  • Never let feeders run empty at night. Hungry birds in a cold shed lose weight quickly and crowd the feeders in the morning.
  • Keep feeder height at bird back level so feed is not spilled into the litter.
  • Follow the starter, grower and finisher change-over days from your feed company. Do not dilute feed with grain to save money; it costs more in poor FCR.
  • Check feed for moisture and mould. Damp winter weather spoils feed bags kept on the floor or against walls. Store bags on pallets, away from walls, and use them in order.
  • Lighting programmes and any feed control to slow very fast growth should follow your integrator or vet. Do not invent your own programme mid-batch.

Gut health in winter: wet droppings and E. coli

Cold stress, ammonia and wet litter upset the gut. Droppings become loose and watery, the litter gets wetter, and the cycle repeats. A healthy gut flora also means better digestion and FCR in the last weeks, when birds eat the most feed.

Remipro probiotic gut conditioner for broilers by IMN Pyrophos

Gut health · Bestseller

Remipro

Probiotics, prebiotics (MOS) and Saccharomyces, with betaine, methionine and vitamin C. Restores healthy gut flora, reduces loose droppings, improves digestion and FCR, helps in coccidiosis recovery and corrects brown or coffee-coloured droppings.

Dose: routine gut health 1 g per 8 kg body weight or 1 g per litre of water; in loose droppings and infections 1 g per 5 kg body weight or 2 g per litre.

500 g ₹626MRP ₹950

If loose droppings come with sudden deaths, the problem may be bacterial (E. coli or Salmonella in the gut), and you need your vet’s diagnosis. Once the cause is known and any antibiotic course is finished, an anti-diarrhoeal support helps the gut settle:

Septima for loose droppings in broilers by IMN Pyrophos

Loose droppings · Bestseller

Septima

Anti-diarrhoeal combination with herbal bioenhancers on a dextrose base. Corrects loose droppings; helpful in sudden mortality from intestinal Salmonella and E. coli, early chick mortality, coccidiosis and necrotic enteritis.

Dose: moderate cases 1 g per 6 kg body weight or 1 g per litre; high mortality 1 g per 4–5 kg body weight or 2 g per litre. In E. coli, use after the antibiotic course. Do not mix with any other drug, sanitiser or acidifier.

500 g ₹793MRP ₹1,300

Ascites and sudden death (SDS) in winter

Ascites, or “water belly”, is a heart and lung problem of fast-growing broilers. A fast-growing bird needs a lot of oxygen. In winter, cold makes it burn more energy and need even more oxygen, while a closed shed with ammonia gives it less. The heart has to pump harder to push blood through the lungs, the right side of the heart gets weak and enlarged, and fluid leaks into the belly. Sudden death syndrome (SDS, “flip-over”) hits fast, healthy-looking birds that die within minutes, often found on their back.

Signs

  • Bluish comb and face, breathing hard even at rest
  • Swollen, soft belly full of fluid; bird stands upright like a penguin
  • Deaths mostly from week 4 onward, and mostly among the heaviest, best-looking birds
  • At post-mortem: yellowish fluid in the belly, enlarged heart, congested lungs

Prevention

  • Minimum ventilation every hour, as above. Ammonia-damaged lungs make ascites worse.
  • Avoid cold stress and night-time temperature crashes, especially in week 2–4.
  • Follow your lighting programme; some dark hours slow the growth spurt and rest the heart.
  • Avoid extra salt: check that water and feed are not high in sodium.
  • Do not handle or chase heavy birds unnecessarily in the last two weeks.
Ascitox Q10 for ascites and SDS in broilers by IMN Pyrophos

Ascites and SDS prevention

Ascitox Q10

A blend of CoQ10, blood buffers, antioxidants, herbal diuretics, sodium ascorbate and selenite. Helps in the prevention and control of metabolic ascites and SDS in broilers.

Dose: in the IMN winter 2026 schedule, per 1,000 birds: 90 g on day 12 and 13, 140 g on day 21 and 22, 180 g on day 30, 200 g on day 36 and 42. If birds start showing water belly (label control dose): 3–4 g per litre in night-time drinking water for 3–5 days, holding feed while it is given.

1 kg ₹698MRP ₹1,080

Ascitox Q10 supports prevention and control; it does not replace ventilation and temperature control. More detail in broiler ascites treatment.

Night management

In winter, most damage happens between midnight and sunrise: the coldest hours, the highest ammonia and nobody watching. One or two short night rounds pay for themselves.

  • Late evening round: feeders full, water flowing, heaters working safely, curtains closed with the top gap, thermometer reading noted.
  • Early morning round (before sunrise): look at how birds are lying. Huddled in corners or under heaters means too cold; panting means too hot or too stuffy.
  • Listen in the quiet: rattling, gurgling or sneezing is an early sign of a respiratory problem (see infectious bronchitis).
  • Check corners and the area near curtains for cold draughts and piling. Piling in cold sheds can smother birds.
  • Walk slowly with a dim torch. Sudden noise or bright light makes heavy birds panic and pile.

Weekly targets: body weight, FCR and water

Weigh at least 50–100 birds from different parts of the shed every week, on the same day and time, and compare with your chick company’s chart. The table below is a rough field guide for well-managed modern broilers; your breed chart is the main reference.

DayAverage body weightCumulative FCR (guide)Feed per bird per dayWater : feed
14About 430–500 gAbout 1.05–1.20About 60–75 gAbout 1.8–2.0
21About 850–950 gAbout 1.25–1.35About 95–115 gAbout 1.7–2.0
28About 1,400–1,550 gAbout 1.40–1.50About 140–160 gAbout 1.7–2.0
35About 1,950–2,150 gAbout 1.50–1.62About 175–195 gAbout 1.7–2.0
42About 2,450–2,700 gAbout 1.65–1.78About 195–215 gAbout 1.7–2.0
  • If weight falls behind for two weeks in a row, check temperature at bird height, feeder and drinker space, and water intake first.
  • Uneven birds (many small and many big) usually mean feeder or drinker space problems, cold corners, or disease.
  • Plan your sale with the market in mind: check today’s broiler rate and work out your profit with the poultry cost and profit calculator.

Daily and weekly checklist

Every day

TimeCheck
Early morningBend-down ammonia test, bird spread, thermometer at bird height, count and remove dead birds
MorningFlush drinker lines, note water use, fill feeders, open top curtains step by step
AfternoonRake litter, remove wet cake, squeeze test, open curtains the most, look for panting
EveningClose curtains in steps, keep top gap, check heaters and chimneys, fill feeders for the night
NightShort round: listen for breathing sounds, check piling, drafts, heater safety

Every week

  • Weigh 50–100 birds and compare with the breed chart
  • Calculate feed used, cumulative FCR and water-to-feed ratio
  • Check all nipples and drinkers for leaks; adjust drinker and feeder height to bird back level
  • Check feed stock for damp or mouldy bags
  • Review mortality: write down the daily count and look for a rising trend
  • Check your vaccination and medicine plan with the winter broiler medicine schedule and your vet

Signs to call the vet

Rising deaths in winter are never “normal cold”. Call your vet and send fresh dead birds for post-mortem the same day if you see any of the signs below. Treatment on guesswork wastes money and time.
  • Daily deaths rising for two days in a row, or clearly higher than earlier in the batch
  • Rattling breathing, swollen faces or sneezing spreading through the shed
  • Blood in droppings, or very watery droppings with dull, fluffed-up birds
  • Several birds with swollen water bellies or blue combs
  • Twisted necks, paralysis or greenish droppings (think of Ranikhet)
  • Sudden heavy deaths with swollen heads or blue combs: report to the veterinary department, as it may be bird flu
  • A sudden fall in feed or water intake without an obvious reason

If your vet prescribes an antibiotic, finish the course as advised and keep the withdrawal period before sale.

Common mistakes in winter broiler management

  1. Sealing the shed at night to “save heat”. This is the number one cause of ammonia, CRD and ascites.
  2. Opening curtains from the bottom, so cold air hits the birds directly.
  3. Using the brooding routine for the whole batch. Birds after day 15 need less heat and more air every week.
  4. Piling fresh litter on top of wet cake instead of removing the cake first.
  5. Ignoring leaking drinkers. One leaking nipple line can wet a large part of the shed in a single night.
  6. Not measuring water use, so the earliest warning of disease is missed.
  7. Coal or wood heaters without a chimney, filling the shed with smoke and gas.
  8. Letting feeders go empty overnight, then a rush and crowding in the morning.
  9. Starting antibiotics on guesswork at the first sneeze, without a diagnosis.
  10. Weighing a handful of birds near the door and believing the flock is on target.

Frequently asked questions

How do I know if my shed has too much ammonia?

Bend down to bird height first thing in the morning, before opening any curtain. If you can clearly smell ammonia, or your eyes sting or water, the level is too high for the birds. Increase fresh air (top curtain gap or fan timer) the same day and look for wet litter near drinkers.

Should I close all curtains on very cold nights?

No. Keep them mostly closed, but leave a small gap at the top on the side away from the wind. Give heat at bird level if needed. A fully sealed shed builds up ammonia and moisture, which does more harm than a little cool air near the roof.

Until what age do broilers need a heater in winter?

It depends on your area and shed. Many flocks need heat at night until about week 3 or 4, and after that only on very cold nights. Watch the birds: if they huddle, they need warmth; if they are spread evenly and eating, they are comfortable. Follow your vet’s advice for your region.

Why do my best, heaviest birds die suddenly in the last weeks?

This is the typical picture of ascites and sudden death syndrome. Fast growth, cold stress and poor air make the heart and lungs work too hard. Improve ventilation, avoid cold nights, follow your lighting programme and talk to your vet about prevention, such as Ascitox Q10 on fixed days.

My birds drink less in winter. Is that a problem?

Some fall is normal, but very cold water can reduce drinking a lot, and then feed intake and growth fall too. Take the chill off the water, flush lines in the morning and keep a daily record. A sudden drop from one day to the next is a warning sign.

How often should I add fresh litter?

Add fresh dry litter whenever wet patches appear, after removing the caked part. In most winter batches that means regular small top-ups near drinkers and in busy areas rather than one big addition at the end.

Can I use probiotics and water sanitiser together?

Generally no. Sanitisers can kill the good bacteria in probiotics. Give them at different times or on different days, as your vet or the product label advises. Septima’s label clearly says not to mix it with any sanitiser or acidifier.

Ammonia smell, wet litter or deaths rising in your shed? Send a short video of the birds and litter, the age, the bird count and the last week’s deaths on WhatsApp +91 98715 84101. Dr. Ibne Ali’s team will tell you what to check first. Ask on WhatsApp

Also read: winter management in poultry farming · wet litter in winter · infectious bronchitis · today’s broiler rate · poultry profit calculator · IMN poultry products

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