Ventilation means bringing in fresh air and taking out bad air: moisture, ammonia, carbon dioxide and heat. In winter you need a small, steady amount of air to keep litter dry without chilling the birds. In summer you need as much air as possible to carry heat away. A control shed does this with fans, inlets and cooling pads; an open shed does it with curtains, side openings and sometimes fans. The aim is the same.
What bad air does
Birds breathe out moisture and their droppings release more. A shed of 20,000 birds puts many litres of water into the air every day, and that water has to leave through ventilation or it ends up in the litter.
When air is not changed:
- Litter gets wet and cakes, which raises ammonia and leads to foot pad burns and breast blisters.
- Ammonia above about 25 ppm damages the lining of the airways, so birds catch respiratory infections more easily and grow slower. Guides like birds to stay below about 10 ppm.
- Carbon dioxide builds up, especially with gas heaters. Aviagen's guidance says chicks get dull and eat less when CO2 passes about 3,000 ppm.
You cannot see these problems, but you can measure and smell them. See our post on litter management for the litter side of the same story.
Winter: minimum ventilation
Many Pakistani farmers close everything in December and January to save gas. That is the most common ventilation mistake. Closed sheds with heaters running in fog weather become wet and full of ammonia within days.
How to run it
- In a control shed, use one or two fans on a timer. University of Kentucky extension recommends a short cycle, such as 5 minutes, over a 10 minute cycle, because long off periods make temperature swing.
- Start small, for example the fan running about 1 minute in every 5, and increase on-time as birds grow.
- Bring air in high, through small side inlets or a gap at the top of the curtain, so cold air mixes with warm air near the roof before reaching birds. Cold air falling straight onto chicks chills them.
- In an open shed, lower the top of the curtain a few inches on the side away from the wind, never on the windy side, and raise it more as birds get older.
How to know if it is enough
Walk in early in the morning, after the shed has been closed all night:
- Eyes burning or a strong smell: not enough air.
- Water drops on the roof or walls: not enough air.
- Litter sticky in the middle and under drinkers: not enough air, or a leak.
- Birds huddled and the heater running non-stop: maybe too much air, or air hitting birds directly.
Check ammonia at bird height, about 30 cm above the litter, just before the fan comes on. Kentucky extension advises increasing fan on-time when it reads above 25 ppm.
Summer: moving heat out
When the outside temperature crosses 32°C and climbs to 40 to 45°C in Punjab and Sindh, ventilation is about wind speed and cooling. Older birds feel cooler when air moves over them. Young chicks do not like strong drafts: in the first days, air speed at chick level should stay very low.
Control shed (tunnel ventilation with pads)
- Fans at one end pull air through wet cooling pads at the other end. Air flows down the shed like a tunnel.
- All doors, holes and broken curtains must be sealed, or air comes in through the wrong place and misses the pads.
- Start pads when the shed is hot, not at sunrise. Running pads too early raises humidity without much cooling.
- In the humid monsoon months, pads cool less, because wet air cannot absorb much more water. Wind speed becomes even more important then.
- Keep pads clean and fully wet. Dry stripes on a pad let hot air through.
Open shed
- Curtains fully open on hot days, with shade on the sunny sides.
- Roof insulation or white paint, and sprinklers on the roof in the hottest hours, help keep heat off.
- Circulation fans or ceiling fans help a lot. Point them along the shed so they push air in the same direction, not against each other.
- Lower stocking density in summer, because an open shed cannot pull heat out of a packed house. Give each bird more space from May to August.
For the full hot-day plan, including water and feed timing, read heat stress in broilers.
Control shed vs open shed
| Control shed | Open shed | |
|---|---|---|
| Cost to build | High | Low |
| Birds per sq ft | More, if well run | Fewer, especially in summer |
| Depends on power | Fully: fans stop, birds suffer fast | Less: curtains still let air in |
| Summer control | Good with pads and seals | Hard above 38°C |
| Winter control | Good with timers and inlets | Curtain skill is everything |
| Main risk | Power cut, generator failure | Heat waves, cold drafts at night |
A control shed is a machine. It works very well while electricity flows, and it can go wrong very fast when the power goes. If you run one, your load-shedding and generator plan is part of your ventilation plan.
Daily checks for the supervisor
- Smell the shed when you first walk in, before your nose gets used to it.
- Look at the birds: spread out and active is good; crowding, panting or wings open means trouble.
- Feel the litter under drinkers and along walls.
- Check fan belts, shutters and pad water flow once a day.
- Write temperatures and fan settings in the log.
Poultry Curve's daily log has space for shed temperature and notes next to deaths and feed, so you can see if a bad night of ventilation lines up with more deaths two or three days later. If you are not sure what your readings mean, ask Helper.
Good air shows up in the numbers: drier litter, fewer breathing problems, better growth and a better FCR. Check the result at the end with the EPEF calculator.