New ISU Lab Targets Link Between Livestock Diet and Air Emissions

September 27th, 2004

The first residents of a new laboratory at Iowa State University arrived Sept. 14. And while the 44-pound pigs get used to their new digs, they're also getting used to a new, low-protein diet.

"We're not taking the Atkins approach here," said Wendy Powers, associate professor of animal science and environmental extension specialist.

Powers is the lead researcher in the new Animal Emission Laboratory. Sarah Bastyr, assistant scientist, is the lab manager. The goal of the research is to discover whether changes in diet can effectively reduce gas emissions from animals in livestock facilities. Results of the work could lead to new dietary recommendations for livestock producers that will improve air quality both inside and outside of production buildings.

To study the impact of diet, a facility was needed to precisely measure emissions. In the new lab, animals of all species can be fed individually or in groups, with emission measurements collected the same way. Money and in-kind contributions for the lab totaling $700,000 came from the ISU College of Agriculture, the Department of Animal Science, small business and private donations.

The laboratory consists of eight rooms for housing animals. Each room can accommodate one horse, one lactating cow, two growing heifers, six finishing pigs, 25 turkeys, 60 broilers or 85 laying hens.

Penning, feed and water handling systems and manure handling apparatus for each species can be removed from the chambers to accommodate the needs of different species. Powers said this flexibility makes the laboratory the only of its kind in the nation.

The pigs now housed in the laboratory will be fed one of three diets until they reach market weight in late January. The diets include protein levels of 20 percent, 18 percent and 16 percent. Manure collected from the animal rooms is measured daily, and matched against the animals' daily feed intake. The project is funded by the U.S. Department of Agriculture.

The new lab has online monitoring capabilities for hydrogen sulfide, ammonia, nitrous oxides, nitrogen oxides, sulfur oxides, methane, carbon dioxide and volatile organic carbons. Through software control, gaseous concentration monitoring of the rooms occurs in sequential fashion, beginning first with incoming air for 30 minutes, then through each of the eight rooms' exhaust airs for 30 minutes. Airflow rates into and out of each room are measured as well, allowing the emission rates of each gas to be calculated.

"For this first group of pigs, we are looking at cumulative emissions over their growth phase," Powers said. "We will do the same with the five flocks of broilers we bring in next spring. Layer hens also will be in the lab next spring, and dairy cows next winter. For these last two species, we will pick key production periods and keep animals in for two or three weeks at a time."

Each room is individually heated and cooled. Temperatures are set independently and dictate the airflow rate in each room. The temperature and humidity of each room are monitored and recorded every two seconds. If the temperature falls outside a specified range, an alarm system places a series of phone calls to alert laboratory personnel.

Does Powers plan to someday fill the eight rooms with a mix of animal species, taking a sort of "Old MacDonald had a farm" approach? "We have the capabilities to do that," she said. "Right now, we're establishing some baseline data for each species so we plan to fill all rooms with a single species for the current slate of projects."

Editor's note: Digital photos of the air emissions lab are available on request. Contact Ed Adcock, (515) 294-2314 or


Wendy Powers, Animal Science, (515) 294-1635,
Susan Thompson, Communications Service, (515) 294-0705,