As layer house designs start to include more cage-free systems and birds have floor access, managers need to look for ways to keep ammonia levels under control.
Excessive ammonia can damage bird health and have a negative effect on production and profitability.
Ammonia is produced when bacteria and enzymes decompose uric acid and other nitrogen-containing waste. Free ammonia produced by decomposition can be released as gas or bound with hydrogen ions to form ammonium, which tends to remain in the litter. A subsequent reaction of sulfate with ammonium results in ammonium sulfate, which is a water-soluble fertilizer and increases the value of used litter.
Major ammonia control mechanisms are adequate ventilation, litter treatments, feed additives and proper nutrition, as well as avoiding leaks in water systems.
Iowa State University's Brett Ramirez said there is a lot to consider when controlling ammonia in poultry housing. Cooler weather may bring more difficulties. (Courtesy Iowa State University)
1. Ventilation
Brett Ramirez, assistant professor in agricultural and biosystems engineering at Iowa State University, offers some considerations when striving for good air quality. He said cooler weather means managers must be more vigilant in observing what’s going on in the house.
- Put on your “ventilation glasses.” Plan to do a walk-through with a different set of observations than looking for the normal floor eggs, dead birds, etc. Are birds piling? How strong is the ammonia smell? Do water lines or areas near the ceiling and wall juncture have condensation, indicating humidity levels are too high? Look for signs of proper air movement.
- A great deal of emphasis needs to go into measuring. Record measurements of environmental conditions to develop a baseline to know when intervention is needed.Technology options are quite diverse. Sensors and controllers connected via the internet can provide real-time measurements of ammonia, carbon dioxide, humidity, temperature and air pressure delivered to a manager’s computer or mobile device. Not all farms are equipped with the latest technology, so conventional monitors and thermometers will also provide useful information.
- It’s important to know the air speeds at inlets. The air speed recommendation at inlets is 800-1000 feet per minute. Static pressure and fan capacity have an important impact on air speed to achieve proper air mixing. If static pressure is too low, cold air drops to the floor near the inlet and creates dead spots. If static pressure is too high, drafts result that will chill birds.
- Pay attention to fans as not all are created equal. Fan designs vary dramatically and move air at different rates. Be sure to keep fan belts tight and shutters clean. Removing a cone can reduce air flow 10 to 15 percent (in cooler climates, pay close attention during winter as sliding snow often damages cones). When changing motors, be sure to use a properly sized replacement.
2. Keep litter dry
Hens with litter access do a good job at keeping litter friable (crumbly) and can move material very efficiently. It is recommended to keep one-inch litter depths and moisture levels below 25 percent. If environmental conditions are optimal, litter caking may be minimized. Some aviary system designs include manure scrapers, which help maintain good litter quality.
There are several types of treatments available to keep litter dry. It’s important to use these products according to the manufacturer’s instructions and ensure they meet certification requirements, especially when producing organic eggs.
Acidifiers lower pH in the litter. This acidic environment reduces or kills bacteria that normally decompose uric acid. Ammonia is bound to form ammonium sulfate. Some examples include sodium bisulfate, aluminum sulfate and sulfuric acid soaked in clay.
Another type of litter treatment is absorbers. These natural materials bind the ammonia. They include zeolite, gypsum and a combination product of diatomaceous earth and calcium bentonite. A finely granulated product produced of seaweed, clay and essential oils picks up moisture efficiently and has been reported to be so safe it can be blown directly over hens with no ill effects.
3. Microbes and enzymes
An emerging option of litter treatments is the use of microbes and enzymes to reduce ammonia production.
Products often contain a combination of a variety of ingredients that may include Bacillus bacteria and enzymes. These products are applied directly on the litter and have varying label recommendations on frequency of application.
Some products also claim to inactivate pathogenic bacteria in the litter as an added benefit. Due to the recent introduction of these products, there is limited published research available.
4. Feed approaches to reduce ammonia
The microbe and enzyme products previously mentioned are also available as feed ingredients.
There is a commercial Bacillus product which, when excreted, is reported to change the manure decomposition process. These Bacilli produce protease and carbohydrate enzymes that affect Gram-negative bacteria, which decompose manure resulting in drier litter and less ammonia.
Also, phytogenic products including herbs with essential oils and other natural products such as tannins and yucca powder have been shown in studies to reduce ammonia in manure.
Other feed ingredients include zeolite, which binds ammonia and gypsum, which acidifies the diet, converting the ammonia to ammonium.
Feed approaches recommended by Kristjan Bregendahl, poultry nutritionist at Devenish Nutrition, include reduced-protein diets and increased fiber. Excess protein in a diet results in higher nitrogen content in manure. A reduced protein approach combined with phase feeding can significantly reduce ammonia emissions.
However, with a reduced protein diet, amino acid ratios need to be carefully monitored to maintain optimum performance. Including fibrous ingredients in the diet, such as corn distillers dried grains with solubles, soybean hulls and wheat middlings, have been shown to reduce manure pH and affect ammonia, again by converting ammonia to ammonium.
Kristjan Bregendahl gives multiple suggestions for feeding strategies that may reduce ammonia. He said excessive salt levels in feed contribute to moisture in litter, which can affect ammonia concentrations in the house's air. (Courtesy Zahler Photography)
Bregendahl also advises that excess salt contributes to wet litter, which increases ammonia concentrations in the air.
Salt is normally monitored in the feed (usually added salt, sodium bicarbonate, and some byproducts that are also high in sodium). Bregendahl also said salt may be in drinking water, especially if the water is chlorinated (excess chlorine can also cause wet litter), from a well source that may be high in sodium or if a water softener is used, which removes calcium but adds sodium.
As a precaution, drinking water should be checked by chemical analysis at least yearly. If sodium levels are too high, the nutritionist may adjust feed formulas accordingly.
5. Monitor for water leaks
One of the easiest ways to prevent ammonia is to ensure the water system is operating properly. After a leak is detected, aerate affected litter and treat with absorbent materials if possible. If litter is too saturated, remove and replace with fresh litter.
Keeping ammonia levels at a minimum is an important part of the battle against respiratory diseases and to achieve efficient egg production. The many tools available offer producers an option of testing them individually and in combination to find the best program for each operation.
Tools for litter management in cage-free layer houses:
