seal  Purdue News

April 7, 2004

Purdue specialists help rewrite outdated livestock standards

WEST LAFAYETTE, Ind. - Today's animal agriculture is a breed apart from how pigs, chickens, cattle and other livestock were raised a generation ago. National guidelines on how livestock and poultry operations should handle animal waste and odor are changing to reflect the times.

Purdue University animal scientists and agricultural engineers are working with colleagues from other land-grant schools to rewrite the outdated standards. The guidelines provide a science-based reference point for livestock producers with concentrated animal feeding operations (CAFOs), as well as the state and federal environmental agencies that regulate them.

The revised standards, due out later this year, are a joint research project of the American Society of Agricultural Engineers (ASAE) and the Federation for Animal Science Societies (FASS).

New manure and air emission standards are long overdue, said Todd Applegate, a Purdue Extension poultry specialist. Applegate heads the ASAE/FASS project's poultry team.

"The standards have not been updated, in large part, since the early 1970s," Applegate said. "Because animal production management systems have changed since that period of time, there was a great need to update the standards. Regulatory agencies, as well as nutrient management planners, use the standards as a baseline for determining such things as the amount of acreage certain operations would need for applying manure and certain design characteristics for the development of new animal facilities."

CAFOs served as an impetus for revising the standards, Applegate said. Modern animal facilities utilize more high-tech equipment than animal buildings did in the past. Also, improvements in genetics and nutrition have shortened production time while reducing total waste volume, Applegate said.

"If we look back to what production systems were like in the duck industry in the early 1970s, for example, you had birds reared outdoors where they had access to concrete waterways," he said. "Compare that to today's systems. Today, ducks are reared either on litter systems or in houses with raised wire, so you've got completely different environmental impacts with the two systems.

"The duck industry can raise a market-weight duck in nearly five to six weeks, where it used to take approximately eight or more weeks. That shorter period of time creates a lot of efficiencies, at least in reducing the amount of nutrient excreted per duck."

Like ducks, there are "holes in the database" for other animal species, Applegate said. The new ASAE/FASS guidelines will attempt to fill those information gaps, he said.

Although CAFOs are regulated, little is known about the possible effects the facilities have on human health. One of the least understood areas is air emission, said Alan Sutton, a Purdue Extension nutrient management specialist who also serves on the guideline revision team.

"From the air quality standpoint, we're accumulating quite a bit of data on the impact of diets on ammonia emissions, hydrogen sulfide emissions and organic compounds," Sutton said. "We're trying to associate the emissions with olfactometry measurements, or what the human nose actually detects. We've got some pretty good parameters now, indicating that we can adjust an animal's diet to change the amount of ammonia emitted and the emissions of some of these organic compounds."

More research is needed, Sutton said. If enough data is accumulated, it would allow the ASAE/FASS team to "develop recommendations that regulators can use as they try to develop policy for air quality areas," Sutton said. "Also, it would allow us to provide good best management practices for producers to help them stay in compliance."

Either way, Sutton believes it is only a matter of time before the U.S. Environmental Protection Agency (EPA) issues regulations aimed at controlling air emissions at CAFOs.

"I don't think there's any question that the livestock and poultry industries are very aware that air quality regulations are going to be coming down the road," he said. "In fact, I know that the EPA has been very active in trying to develop some sort of regulation or standard.

"Some of the individual states already are acting and have some air quality-type measurements in proposed legislation. That's why we're working feverishly to try to get some baseline emission values from different size operations. We also need to show how we can minimize those emissions."

Sutton added that the revised guidelines could have the greatest impact on nutrient management planning and the size of manure storage facilities.

Other land-grant schools taking a leadership role in the ASAE/FASS project include Iowa State, Oklahoma State, Texas A&M and Washington State universities; and the universities of California-Davis, Kentucky, Missouri and Nebraska.

Writer: Steve Leer, (765) 494-8415,

Sources: Todd Applegate, (765) 496-7769,

Alan Sutton, (765) 494-8012,

Ag Communications: (765) 494-2722; Beth Forbes,
Agriculture News Page

Related Web site:
Purdue University Department of Animal Sciences

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