Manure Manager

Features Applications Poultry
Poultry flooring system yielding positive manure management results

January 5, 2009  by Tony Kryzanowski

Industry, government and researchers in the United States are
cooperating on a project to design, “the poultry house of the future,”
research that could result in a more positive manure management
situation for poultry producers.

Industry, government and researchers in the United States are cooperating on a project to design, “the poultry house of the future,” research that could result in a more positive manure management situation for poultry producers.




Chickens raised on a new poultry house plastic flooring system actually increased in weight by 5 to 15 percent.


The project is being conducted at the University of Maryland, Eastern Shore (UMES) campus with the objective of providing the industry with poultry house design improvements that address a variety of challenges. Researchers are taking particular aim at flooring, heating, managing relative humidity, and growing birds with multiple ages on the same farm.

A key aspect to the research is a new plastic flooring and ventilation system designed by engineering firm AviHome LLC, located in Salisbury, Maryland. The flooring system consists of plastic interlocking squares, measuring about 18 inches by 18 inches. It sits about three inches off the ground, and is supported by peg legs located on the corners of each plastic section. There are tiny holes in each section. Coupled with a ventilation system, air funnels through the holes and results in the drying of the chicken fecal matter.

“Because of the ventilation and the wicking ability of the water through the fecal material, the newer material on top of the old continues to dry,” says UMES researcher and project leader Dr. Jeannine Harter-Dennis.

The plastic flooring system is sturdy enough to allow equipment to be driven on it so the manure can be scrapped between growing cycles.



The new poultry house flooring system eliminates the need to use litter, such as sawdust and wood chips on the floor. This results in a much drier and more concentrated type of manure between broods.


During research trials, chickens were on the plastic flooring on a six-week cycle in what Dr. Harter-Dennis described as an “environmental house,” where researchers were able to raise a flock of about 500 chickens in environmentally controlled chambers. They measured such critical items as air input, air output and air quality insofar as the functioning of the flooring and ventilation system was concerned.

Results so far are better than expected. No expensive floor litter is required and moisture content in the chicken excrement has been reduced to as low as 20 percent in some cases, versus the typical 35 to 40 percent.

Moisture is a key ingredient in the production of ammonia gas, and moist, nitrogen-rich, poultry house litter is ideal for growing the bacteria that are critical in the production of ammonia. If producers can reduce the moisture, bacterial growth is greatly reduced, resulting in less ammonia production. Less ammonia also solves the perpetual problem of odor emissions from conventional poultry houses. Right now, industry handles the ammonia problem by applying an acidic product to the litter between production cycles to lower the pH in the litter, which also acts as an inhibitor.

“When chickens were grown in an environment with the new flooring and ventilation system, our preliminary results show that the ammonia was totally eliminated,” says Dr. Harter-Dennis. “I’m very pleased about that because when the fecal material hits the ground, it dries very rapidly and the lack of litter keeps the pH down below seven most times.”

Researchers have also witnessed between a five to 15 percent improvement in growth of the chickens.

However, Dr. Harter-Dennis acknowledges there are some design challenges related to poultry litter and manure falling through the holes in the plastic flooring onto the floor below. AviHome is aware of the problem and is working on a solution, looking at a new hole design or a water permeable layer that could be placed over the flooring.



The flooring system sits about three inches off the ground, and is
supported by peg legs located on the corners of each plastic section.




AviHome LLC of Maryland developed the flooring system, which consists of plastic interlocking squares, each measuring about 18 inches by 18 inches.


With the production of a drier, more concentrated waste product from the use of this flooring and ventilation system, a new scenario for poultry manure management could be created for the future. The industry could find itself producing large amounts of concentrated and nutrient rich manure instead of the usual mix of bird excrement and litter.

“It’s a much more concentrated product that could be maybe trucked off the eastern shore (of Maryland) to some place that needs it,” says Dr. Harter-Dennis. The resulting manure could be used as an organic fertilizer.

At present, the area’s poultry industry is producing more manure than it can absorb and applies most of it as fertilizer on local cropland in the spring. Over time, this has led to a significant phosphorus build up in local farmland, which is another reason why less manure volume and the ability to store it over a longer period of time is a positive development. Growers will have less waste to manage. Perdue, one of four major poultry producers in the area, accepts a lot of the area’s excess manure, pelletizes it and exports it as a lawn amendment for residential use. With this more concentrated product, the whole concept of its disposal and commercial potential needs to be revisited, Dr. Dennis-Harter says.

In the past, growers used a four to six inch thick layer of wood shavings and sawdust litter as an absorbent floor material in poultry houses, adopting this practice because these materials were readily available as a byproduct of the timber industry. However, that situation has changed.

“Now, we cut down trees just to make litter,” says Dr. Harter-Dennis. “It’s become a product, it’s expensive, and sometimes hard to get if not impossible. So if we can grow chickens without litter, we save a resource, plus we don’t have the volume of a waste product that we would have if we were still using the wood chips and sawdust.”

The litter used in a poultry house on a contract grower’s farm will actually remain in that house for several years. Between each flock, which is usually a period of seven to eight weeks to grow a broiler chicken from a one to two ounces to 5.5 pounds, there is about a two week period where the crust on top of the litter is removed and stored. Because the litter is used over and over again, there is a build up of nitrogen content that leads to the production of ammonia gas. This is a major challenge for the industry as it can affect a bird’s respiratory system, lead to blindness within the bird population, impact negatively on growth, impact human health among industry workers, and present both odor and environmental challenges when vented.

The current method to manage the ammonia gas is to exhaust it from the poultry house. Research has shown that vented ammonia contributes to the formation of particulate matter that through a cascade of events leads to the development of smog. The U.S. Environmental Protection Agency (EPA) is looking at air quality and aiming to limit the exhausting of ammonia from intensive farm operations in particular.

“If we don’t self-regulate, we’re going to get governmentally regulated for the ammonia emissions,” says Dr. Harter-Dennis. “We’ve got people in Washington that don’t know very much about agriculture or animal production in general, making laws for us and we as producers want to be pro-active rather than reactive and present them with something that is reasonable and feasible that won’t destroy the industry.”

Researchers hope the poultry house floor and ventilation system will control emissions at a level acceptable to the EPA, and can be retrofitted into existing poultry houses.

The flooring and ventilation system research program is currently entering a new phase, moving from 500 chickens to a facility that can house 12 groups of 500 chickens each. Six groups will be raised in conventional growing conditions and six will be raised in the new plastic flooring and ventilation environment. The plan is to eventually install the system into four commercial broiler houses on the UMES farm where chickens are grown for Allen’s Family Foods, to test it in an actual commercial application.


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