Researcher Studying Feedlot
Products Other Than Red Meat

By David Bowser

AMARILLO — A Texas Panhandle researcher is studying ways of improving the quality of manure while decreasing the amount produced in area feedyards.

Dr. Andy Cole, a USDA animal nutritionist at the agricultural research station here, is exploring ways of dealing with or preventing waste at feedyards across the Texas Panhandle, Western Oklahoma and Eastern New Mexico.

Confined animal feeding operations, or CAFOs, with more than a 1000 head of cattle have created stockpiles of manure. Some of these stockpiles in the Texas Panhandle are 20 to 30 years old.

Potentially, this manure can have a number of effects on the environment, Cole says, particularly with regard to surface and ground water.

"This is not much of a problem as long as you have a good run-off retention facility and as long as we have cattle in the pens," Cole says.

He explains that research indicates little percolation of water down through the pen surface because of compaction.

"It's when the pen becomes idle for several years that we might start getting some leaching due to the feedyard," he says.

There can also be air quality problems due to CAFOs and the manure produced by the animals in them. Most cattle feeders think primarily of dust, but with new EPA regulations coming out concerning microscopic particles, Cole says the particles that cannot be seen may be more of a problem than particles that can be seen.

"We have these animals in a feedyard," Cole says. "We import a lot of feed. When an animal leaves, part of the nutrients in that feed leave as meat or tissue in that animal, but most of the nutrients actually end up being lost in the urine or feces or gas, such as carbon dioxide or methane."

For example, nitrogen from the urine or feces can evaporate as ammonia or another odor-producing compound, or run off into a lagoon. Part of these losses will be collected as manure and carried away. Part of it, he warns, will end up as dust that can be carried downwind from the feedyard.

Data from research in Nebraska concerning the intake of nitrogen indicates a 10,000-head feedyard over a year's period will feed about 1.6 million pounds of nitrogen.

"The animal leaves with about six percent of that," Cole says.

About 57 percent, according to the Nebraska trials, left the feedyard as ammonia released into the atmosphere. About 17 percent was in the runoff from the feedyard, and only about 17 percent was collected in the manure.

The loss as ammonia, Cole admits, is highly dependent upon the acidity of the soil, temperatures and moisture conditions.

"Down here in our drier climate, this could be a whole lot less," he says.

He is conducting research at the Bushland experiment station to get a more accurate number for such losses in the Panhandle of Texas.

Another nutrient of primary concern is phosphorus.

"We'll feed almost a quarter of a million pounds of phosphorus in a 10,000-head feedyard," Cole notes. "Much of it ends up in our runoff. It's going to end up in our playa lake or our lagoon."

"The animal only takes about two percent of the phosphorus we feed," Cole explains.

As for runoff, Cole notes that in other parts of the country some swine operations have had problems when lagoons broke and several million gallons of contaminated water flooded streams or creeks.

"Luckily, up here on the High Plains, we don't have very many streams or creeks to worry about," Cole says.

In addition to losses of nutrients to water runoff, there are potential problems with losses to the atmosphere, the researcher says.

"We have quite a bit of dust problems," Cole points out. "They may not result in loss of nutrients, but we sure have neighbors complaining about it."

If ammonia is combined in the atmosphere with nitrous oxide or sulfur dioxide, it can form particles that are included in the new EPA clean air regulations.

"California right now is looking at this very carefully as far as starting to regulate the ammonia being emitted from dairies," Cole says. "They are planning on having a plan for ammonia emission standards for CAFOs within the next two years.

Overseas, the Netherlands already has ammonia emission standards.

"To meet the standards they have set for the year 2001, the Netherlands are estimating that they will have to reduce their dairy cow population by 50 percent and their hog population by 50 percent," Cole says. "If it's happening in California, if it's happening in Europe, then we need to think that it may happen here in the future."

One of the concerns about cattle in feedyards is methane.

"As soon as someone starts talking about cattle flatulence," Cole says, "I know they don't know what they're talking about. I tell them they're talking about the wrong end of the cattle. It's coming out of the front end, not the back end."

A good thing about feedlot cattle, Cole says, is that because of the high concentrate diets that are fed, the methane production is less than from a dairy cow.

"It's about one-fifth what it is for a dairy cow," he says. "It's about one-third of a beef cow on grass."

For diary or range cattle, methane production is from seven to ten percent of the energy of the diet, while with feeder cattle, it's two to three percent.

"However, because we have stockpiled manure there that can also ferment and produce methane," Cole says, "it can be a problem."

Methane may be up to three or four percent of a stockpile of manure, but if it is composted, the ammonia emissions are reduced.

"How we handle that manure may affect it," Cole says. "How we feed that animal may affect it."

Land application is the preferable way of disposing of the manure, Cole says, but there are a number of constraints in using manure as a fertilizer.

"For one, the nitrogen-phosphorus ratio is incorrect," Cole says. "Most plants require a nitrogen-phosphorus ratio of about five-to-one. By the time we've collected the manure from the pen, stockpiled it and gotten it to the field, our nitrogen to phosphorus ratio is closer to one-to-one. So when we put on 10 tons of manure to meet the nitrogen requirement, we're putting on five times too much phosphorus."

Right now, that can be done, Cole says, but in the future, once a certain level of phosphorus is reached in the soil, no more phosphorus should be added except for what the crop can use.

"Then, we'll have to apply manure based on phosphorus, which means it's going to take five times more land for the manure than if we were applying it based on nitrogen requirements," Cole says.

He also explains that almost all the phosphorus in manure is available to plants, but only about 50 percent of the nitrogen is available.

There are also questions about transportation costs. Ten or 15 miles is about as far as feedyard manure can be transported economically.

"I know people who are hauling it 25 miles so they can get rid of it," Cole says.

There is also a problem with inconsistent composition.

Cole says there are ways of changing dietary regimes to reduce the quantity and to improve the quality of feedyard manure.

"By improving the quality, I mean making that manure a better product for use as a fertilizer or in coal-fired power plants," Cole says. "You can modify manure composition for specific purposes."

Research indicates that how the animal is fed affects the amount of manure produced.

"Right now, we're feeding very high concentrate diets," Cole says. "There's very high starch availability in those diets. We may be almost as low as we can go as far as quantity of manure that's being produced, but we can affect the quality of that manure both, by the diet and management."

Research from Australia indicates that odor can be changed. The studies show that manure from cattle fed milo has a more foul odor than that from animals fed barley. Their research, Cole says, did not include feeding corn.

Cole says feedyards may also be able to change the amount of dust produced.

"We can kick up the amount of fat in the diet, and we may be able to reduce the amount of dust that is produced," he explains.

The quality of runoff may also be affected by the solubility of the nutrients in the manure.

There are also concerns about the effects of a feeding operation on wildlife, particularly duck and migratory water fowl.

"Some wildlife people are concerned about migratory birds that come in and land on our playa lakes, that we may be killing them with the toxicity of zinc or copper or selenium, or whatever accumulates in those waters in our playa lakes," Cole says. "Many times during the year, the only wet ponds in the Panhandle are the ones in the feedyard."

That's 66 out of 19,000 playa lakes in the Texas Panhandle.

The phosphorus requirement for a duck is about .7 percent.

"If he's eating corn in a field near a feedyard, he's only getting about .2 or .3 percent," Cole notes.

It appears that when the duck is on a playa lake, the feeding industry is balancing his phosphorus needs, Cole says, but there is also a need to study the effects of zinc, copper, selenium and other minerals on wildlife.