The Hidden Cost of Ammonia in Broiler Houses
Ammonia (NH₃) is produced by the microbial breakdown of uric acid in poultry litter. It is a colorless gas with a sharp, pungent odor that irritates the respiratory tract of birds and humans alike. The damage ammonia causes to broiler performance is well-documented: reduced feed intake, increased FCR, higher mortality, greater susceptibility to respiratory disease, and impaired immune function. What makes ammonia particularly dangerous is that the levels that cause economic damage — 10–25 ppm — are often below what the human nose can detect.
The financial impact of chronic low-level ammonia exposure is substantial. Research has shown that broilers exposed to 25 ppm ammonia from day 28 have feed intake reduced by 5–10% and body weight reduced by 3–8% compared to birds in clean air. On a flock earning $0.06 per pound of live weight, a 5% weight reduction on 120,000 pounds of production costs $360 in lost revenue — and that does not include the FCR penalty or increased medication costs.
How Ammonia Affects Broilers
Ammonia damages the cilia — the microscopic hair-like structures that line the respiratory tract and sweep away pathogens and particulate matter. When cilia are damaged, bacteria and viruses have easier access to the lower respiratory tract, increasing the incidence and severity of respiratory infections. The inflammation caused by ammonia exposure also diverts energy away from growth toward immune function, worsening FCR.
Broliers exposed to elevated ammonia levels show reduced feed intake, since the gas irritates the eyes and respiratory tract, making birds less willing to move to feeders. They have impaired growth because reduced feed intake plus increased immune system energy demand slows weight gain. They also have higher mortality, particularly from respiratory diseases, and worse FCR because more feed energy goes toward maintenance and immune response rather than weight gain.
Monitoring Ammonia Levels
Because the human nose cannot reliably detect ammonia below 20–25 ppm, objective measurement is essential. Several monitoring options exist. Handheld gas detectors with electrochemical sensors cost $200–$800 and provide spot-check readings at bird level. Passive diffusion tubes (dosimeter tubes) cost less per reading but provide a time-weighted average rather than real-time data. Fixed ammonia sensors installed in houses provide continuous monitoring and can be connected to ventilation controllers. Ammonia test kits using chemical color-change reactions are the most affordable option for growers who want basic spot-check capability.
Readings should be taken at bird level (not at human standing height) in multiple locations across the house. Ammonia concentrations are highest near the litter surface. Readings near exhaust fans will be lower than readings in the center of the house.
Controlling Ammonia Through Ventilation
Minimum ventilation is the primary tool for ammonia control during cold weather. The minimum ventilation rate must be sufficient to remove ammonia produced by microbial activity in the litter. As birds grow and litter mass increases, minimum ventilation rates must increase. A common rule is 0.3–0.5 CFM per bird during brooding, increasing to 1.0–2.0 CFM per bird by week 6.
Inadequate minimum ventilation is the most common cause of elevated ammonia levels. Growers often run minimum ventilation at too low a rate to save fuel, not realizing that the fuel savings are more than offset by performance losses from ammonia exposure.
Litter Management for Ammonia Control
Dry litter produces less ammonia than wet litter. Keeping litter moisture below 30% is the most effective long-term ammonia control strategy. Fixing drinker leaks, managing humidity through ventilation, removing wet spots promptly, and using litter amendments between flocks all contribute to lower ammonia levels during the grow-out cycle.
Litter amendments like alum (aluminum sulfate) and sodium bisulfate lower litter pH, which shifts the chemical equilibrium away from gaseous ammonia and toward non-volatile ammonium. Amendments are typically applied between flocks at rates of 50–100 pounds per 1,000 square feet, depending on litter condition and product specifications.
Logging Ammonia Data
Tracking ammonia readings across flocks helps growers identify houses and seasons where ammonia is a recurring problem. A house that consistently runs 15–20 ppm during minimum ventilation periods may need ventilation system upgrades, different litter management, or more frequent decaking. Without data, these chronic problems go unnoticed and continue to erode flock performance flock after flock.