Ammonia is the smell you stop noticing and the birds never do. It damages respiratory tissue, suppresses feed intake, burns footpads, and drags FCR — and it does all of that at levels below what the human nose can reliably detect. The threshold that matters is 10 ppm at bird level: below it, birds breathe clean air and convert feed normally; above 25 ppm, respiratory damage and performance loss are documented; above 50 ppm, growth and FCR are seriously impaired. This page covers the thresholds, the litter management that keeps ammonia down, and the monitoring method that does not depend on your nose.
What Each Ammonia Level Does
| Level at Bird Level | Effect on the Flock | Your Response |
|---|---|---|
| Below 10 ppm | Normal air quality — respiratory health intact, intake and conversion on curve | Maintain litter dryness and ventilation; keep logging readings |
| 10–25 ppm | Subclinical damage — ciliated airway tissue stressed, birds more vulnerable to respiratory challenge | Investigate litter moisture and ventilation this week; treat as a warning band, not a pass |
| 25–50 ppm | Documented respiratory damage, reduced feed intake, FCR penalty; footpad lesions from wet litter compounds | Act now: increase ventilation for air exchange, find and fix the moisture source, evaluate litter amendment |
| Above 50 ppm | Growth and FCR seriously impaired; mortality risk rises, especially in fast-growing birds | Emergency ventilation and moisture correction; expect performance loss already banked — see the growth bands for what it cost |
Why Litter Gets Wet: The Sources to Find
Ammonia is produced when litter moisture and uric acid meet — so every management question about ammonia is really a question about moisture. The sources, in the order they usually matter:
- Water system leaks. Dripping nipples, sweating lines, and pressure too high for bird age are the single biggest litter-wetting source on most farms. Walk the lines with a paper towel test at bird level — if it gets wet under a nipple without a bird drinking, that is your ammonia budget disappearing.
- Ventilation short of the moisture load. Minimum ventilation exists to remove moisture; under-ventilated winter houses ammonia climbs even with dry-looking litter. Static pressure and fan runtime tell the truth the litter surface hides.
- Spillage and overfilling. Feed in the litter adds moisture and uric acid substrate together. Pan management is ammonia management — see the feed cost guide.
- Cooler temperatures and condensation. Cold walls and ceilings drip; the puddles under condensation lines become ammonia factories. Insulation and air-leak management matter in cold climates.
Between Flocks: The Downtime Window
The cheapest ammonia control of the year happens between flocks: remove old litter or dry and reuse it properly, correct the water system leaks you found during the grow-out, and apply an ammonia-binding litter amendment at downtime per its label — acidifying amendments lower litter pH and keep ammonia from forming in the first place. A litter program is a downtime project that pays out over the next 42 days; a grow-out ammonia problem is an emergency that pays out at settlement.
Monitoring and Money
Read ammonia at bird level with a sensor or kit at the same point in the daily walk — morning, at the litter surface near the birds, not at the ceiling. Log the reading with the litter condition and temperature; the litter management guide covers the moisture side in depth. The money case is direct: a flock running 10% light at day 42 has lost roughly 19,200 lb across 30,000 birds, and chronic ammonia exposure is one of the commonest reasons — via respiratory damage that suppresses intake and conversion long before mortality shows it. Ammonia management is break-even management: the same birds, fed the same feed, converting worse because the air was wrong.
Tracking Litter and Air in Poultry Log™
Litter condition notes, ammonia readings, ventilation settings, and temperature logged in Poultry Log™ sit on the same timeline as water, feed, and mortality — so an ammonia trend shows up against the growth curve it is affecting, not in a separate notebook. When the cause review points at respiratory pressure, the reading history is the evidence that names it. Each flock's litter and air record feeds the profitability dashboard as part of what conversion actually cost.
- 2026-10-05: Comprehensive rewrite. Threshold table, moisture-source breakdown, downtime window, and monitoring method — replacing the earlier short note.
- Earlier version: brief note on ammonia's hidden damage.