DeepLoop Team · 2026-07-13
Cold-Weather Ventilation: What Ross, Cobb and the Data Actually Say
Cold-weather ventilation is where broiler performance is quietly won or lost. Every winter, houses get sealed tight to hold temperature and save fuel — the panel reads perfect, while ammonia and CO2 climb toward levels both Ross and Cobb management guides warn against, and the damage to young birds doesn't wait for the next inspection round.
The sealed-house problem
The problem isn't that teams don't know the targets. It's that holding them 24 hours a day, across every house, is more than any inspection schedule can verify. A manager walks each house maybe three times a day. Problems don't wait for inspection rounds — the coughing starts at 2am, the clustering happens in house 7 while the manager is in house 2.
What Ross and Cobb actually specify
Ross and Cobb's own management guides agree on the numbers: minimum ventilation rates and house temperatures by bird age, fan cycle timing, and the air-quality limits both breeds share — ammonia under 10 ppm, carbon dioxide under 3,000 ppm. The chart below brings both references together in one place.
Ross and Cobb minimum ventilation and air-quality targets across the 42-day broiler growout.
The camera evidence it's real
Researchers at UNICAMP and UNESP (Massari et al., published in Animals, 2022, CC BY 4.0) built two computer-vision measures from overhead footage of a broiler pen — a cluster index and an unrest index — and tracked how flock movement changed with the rearing environment. Their finding: movement was consistently higher in thermoneutral (comfort) conditions, and heat stress substantially reduced activity. Enrichment increased clustering, and birds gathered around enrichment objects specifically under heat stress.
The same pen in comfort versus heat stress — visible difference in bird distribution, no sensor required.
The paper's unrest index: movement drops measurably as environmental conditions push birds toward heat stress.
None of this is new knowledge to an experienced stockperson — reading a flock from the doorway is a skill built over thousands of houses. What's new is that the same reading can now run continuously, on every house, at 2am, without anyone standing there.
Why a sealed house isn't a safe house
Sealing up doesn't just trap gas — it changes the physics of the air itself. University of Georgia ventilation data shows that at 21°C outside, air from a typical sidewall inlet travels about 8 metres along the ceiling before dropping to bird level. At -1°C outside — same inlet, same opening, same static pressure — that throw collapses to about 3.5 metres. Nothing on the controller changed. Cold air is simply denser: it loses its jet sooner and falls short of the house centre, landing on birds instead of mixing with warm air at the ceiling first. That's what a winter draft actually is — not a broken fan, but a working system doing exactly what it was set to do, in weather it wasn't set for.
Static pressure and inlet air throw by outside temperature — University of Georgia Department of Poultry Science.
Where this is heading
DeepLoop is building AI monitoring that watches what happens between inspections — turning the same behavioural signals a camera can see, at 2am, in every house, into the same read an experienced manager makes standing in the doorway. Not replacing that read. Extending it to every hour of every day.