Helping Hogs Smell Better

By Randy Weckman

There’s good reason that no entrepreneur has tried to market a cologne called Eau d’ Sooey or Evening in the Hog House.

Hog odors are the number one complaint people have about concentrated hog production. But several UK researchers are trying to eliminate those smells.

One approach that is getting worldwide attention is to take the smells of the hog house and send them sky high.

At least that’s what biosystems engineer Richard Gates hopes he can do. Gates is currently testing a system that takes the malodorousness of the hog house and sends it into the ether.

His rationale is this: If he can send the odors high enough into the sky, the smells will dissipate before they come back down. And so far, his first efforts suggest that the idea is worth pursuing.

Using tall, skinny, stainless steel chimneys equipped with powerful fans at their base, Gates has been able to send the unpleasant smell from the hog house 80 feet into the air. And by the time the smelly stuff drifts back down to terra firma, he hopes the gases that create the unpleasant smells will have been so diluted with fresh air that we humans won’t smell them. Bloodhounds might, but not humans. Then again, bloodhounds don’t complain much about their neighbors.

Up, Up, and Away

That in a nutshell is Gates’ concept of dealing
with unpleasant odors from swine buildings a good-neighbor concept if there ever was one. But like so many seemingly straightforward concepts, the devil is in the details. Those include: How many hogs, how much smell, how high the chimney or stack, and how much temperature and wind? In terms of the practical, how close to human dwellings? And not the least, how sensitive the nose?

The gleaming stacks Gates designed are being tested under varying conditions at the Woodford County Animal Research Center. The hog barn, located within shouting distance of Versailles, is beyond state-of-the-art. It is the state-of-the-art five years or more from now. On the outside of the low barn, like pipes from a church organ, the 48 smokestacks— or smellstacks— rise 39 feet in the air. With high powered fans inside the stacks at their base, the chimneys send the smells emanating from the hog house up another 40 feet or so— depending on the weather— so that the plume of gas gets well mixed with air before the molecules drift back down to earth.

While Gates has measured how far up the fans blow molecules— he tested the smellstacks by releasing purple smoke at various parts of the building— he still has to work out whether the fans are large enough to keep things smelling rosy at ground level under various weather conditions.

“When the wind is blowing hard— which sometimes it does in early spring— we can expect that the plume of gases from the hog house won’t rise as high as when the weather is calm,” he said. “We have to figure out the size of the fans to make sure that we can eliminate hog house smells in nearly all weather conditions. Some neighbors may have a low tolerance of hog house odors.”

On-going Research

Gates also said his research will investigate
various building materials from which to
construct the smokestacks in an effort to make the concept affordable for the average hog farmers. His are of stainless steel, a relatively expensive building material.

“We designed these particular stacks out of stainless steel for a couple of reasons. First, some of the gases coming from the hog buildings are quite corrosive; second the smooth surface of stainless steel will allow us to research other odor abatement technologies,” Gates said.

Those abatement technologies include wet scrubbing, which consists of misting water at the top of the stacks, while the fans are blowing upward— creating a scrubbing effect that removes dust particles from the exhaust air. Some of the odors associated with animal agriculture become impregnated in the dust particles; thus, removing them with the wet scrubber will eliminate them in the air.

Ozonation is another technique that the unique facility will allow researchers to investigate. In ozonation, ozone (O3, a byproduct of creating electricity) is mixed with the gases coming through the stack of the hog houses. As the ozone is mixed with the smelly gases, it oxidizes them (breaks them into component parts), yielding odorless, harmless gases. When ozone is mixed with ammonia, for example, the outcome is gaseous nitrogen and water vapor.

“The research into hog house environments will help us provide precise, science-based data if government organizations seek to more closely regulate the animal industry,” Gates said.
His idea and structure have created a great deal of enthusiasm worldwide, with scientists from the Silsoe Institute, formerly associated with Oxford University in England, sending scientists to the Versailles (Kentucky) research farm to see the big chimneys.

Multi-Disciplinary Approach

Animal scientist Gary Cromwell has joined forces
with biosystems engineers Larry Turner and Joe
Taraba to investigate another way to help alleviate the odor problem from hogs. His approach uses precision feeding to cut down on the amount of nitrogen in hog manure.

Two of the most odoriferous outcomes of swine production— through the decomposition of manure— are hydrogen sulfide (which smells like rotten eggs) and ammonia (which can bring tears to your eyes if its concentration is strong). In addition, both of these gases can cause major problems for workers and the animals in the hog house if concentrations get too high.

Cromwell, who specializes in swine nutrition, knows that the amount of nitrogen— an element that combines with hydrogen to form ammonia (NH3)— increases when high protein rations are fed to hogs. (Remember that protein is made up of mostly nitrogen along with carbon hydrogen, oxygen and sometimes sulfur.) Excess protein isn’t utilized and is excreted with the manure and urine. When bacteria start to break down the excreted protein into its component parts, the nitrogen is released and recombines with hydrogen to form ammonia, which can make the pigs in the hog house sick and the neighbors uneasy.

The key to Cromwell’s research is the knowledge that protein is utilized according to its composition. Proteins are made up of amino acids, ten of which are essential for animal life. Because animal feeds differ in the relative amounts of amino acids they contain, they sometimes are overfed so that the animal gets enough of a particular amino acid that might be in short supply. Corn, for example, is well-known to be short in the essential amino acid lysine. Thus, to get the right balance a hog needs, he may have to eat more of a high-protein supplement (like soybean meal) than he needs for growth so he receives enough lysine. The hog extracts the lysine he needs during digestion and the remainder is excreted as manure and urine, both rich in nitrogen.

Cromwell’s research has shown that supplementing standard feeds with amino acids to “balance” them more fully allows producers to feed less protein-containing feed, which leads to less nitrogen excretion. Less nitrogen, less ammonia. And it appears that a low crude protein diet, with amino acid supplementation, also reduces hydrogen sulfide emissions from the manure.

Cromwell found that a 10.5 percent crude protein diet (comprised of corn-soybean meal but fortified with the amino acids lysine, threonine, and tryptophan) led to a 50 percent reduction in ammonia generation in manure. At 16.5 percent crude protein the resulting manure produced ammonia levels of 21.4 parts per million; at the fortified 10.5 percent crude protein level ammonia production was reduced to only 10.1 parts per million. And because the limiting amino acid in the feed was added as a supplement, growth of the hogs in the test was unaffected.

In his research Cromwell also has evaluated other feed additives purported to reduce odors from hogs. Indeed, in his experiment with four of the products, the amount of ammonia generated from the hogs decreased substantially.
“Our research indicates that hog producers can reduce odors from ammonia production by lowering the dietary protein or adding certain feed supplements to the swine diet,” Cromwell said.

What Goes In...

Odors from hog production, however, don’t just
come from the hog house. Modern swine
production involves storing manure until it can be recycled onto farm land. These storage units— sometimes pond-like lagoons or container-type storage tanks— can be a major source of odors if they aren’t operating correctly.
The science is this: as the manure starts to break down due to bacteria in the lagoon or tank, various gases are formed— and some are unpleasant.

The swine facility at Woodford County Farm uses a storage tank to contain the waste from the swine operation. That enclosed tank is connected by duct work to a biofilter, which is a huge, thick mat of moist organic matter in which bacteria thrive. Those bacteria inhale, so to speak, the odorous gases and decompose them into odorless gases and water.

The container tank can be emptied and the sludge injected onto the crop land of the 1,440-acre farm. Injecting the stuff, rather than spraying it, keeps odors down to a minimum while returning the nutrients back to the soil.

The system, designed by biosystems engineer Joe Taraba, had two criteria. First, the nutrients returned to the soil had to be no greater than the amount that crops use for growth. Second, the waste material had to be kept from entering into the water supply. (This is particularly important, because like many other farms in the Central Blue Grass region, this farm sits atop a karst— or cave— geology.)

To make sure that both criteria are met, Taraba has installed monitoring systems throughout the farm that record daily a variety of substances in the ground water, including nitrate nitrogen, phosphorus, organic compounds, and bacteria.

“Although the purpose of the swine facilities is to allow researchers to conduct nutrition research, the fact that we will have such an aggregation of swine at this location means that we need to control both odor and potential pollution to groundwater. Thus, the research at the farm is multi-faceted,” Taraba said.

Creatures from
the Black Lagoon

And that’s where the research of animal scientist Melissa Newman comes in. She explores the creatures of the lagoon— anaerobic bacteria. (Anaerobic bacteria thrive in oxygen-deprived media.)

“The majority of lagoons used in swine production today are anaerobic lagoons, usually very deep with small surface areas. The bacteria and the enzymes they produce are very efficient in decomposing most kinds of organic matter. Unfortunately, they often give off large quantities of unpleasant odors,” Newman said.

Her research seeks to maintain the bacteria’s keen ability to decompose the organic matter while minimizing the odors associated with the process. Specifically, her research is two-pronged: investigate the use of enzymes that can be added to the lagoon to enhance fiber degradation; and alter the normal bacterial population in lagoons to favor organisms— odor eaters— that degrade odor-forming compounds such as volatile fatty acids and phenolic compounds.

If these researchers are successful, you may want to schedule your next garden party or soiree at the swine facility in Woodford County.

top

What Causes Hog Odors

Hog odors are caused by some 150 gases that result from the bacterial decomposition of manure. These gases tend to travel in a plume and often are noticeable even at considerable distances unless they are diluted with fresh air.

Odors come from hog barns where manure is coupled with the heat of the hogs themselves, which amplifies the odor. (A freshly scrubbed pig in a freshly washed room has almost no detectable odor.)
Odors also come from lagoons, which are man-made ponds that hold the soup mixture of water, manure, and urine, a nasty broth that is attractive only to bacteria and their ilk. The bacteria that inhabit lagoons break down the mixture into component parts.

It is during this breakdown that smells intensify, as you could imagine.

The Porcine Palace
at Woodford County Farm

The swine facility at the University of Kentucky’s
Animal Research Center in Woodford County is setting the current standards for swine production, and its appurtenances are not just for show. The facility is built for traditional swine research, including nutrition, reproduction and the like. It also is the venue for research into environmental quality issues, including the environment in the hog house, as well as on the entire farm.

Conspicuous is its waste management system that will return all nutrients back to the farm. In essence, all feedstuffs will be grown on the farm, fed to livestock— including sheep, cattle, and horses— and then the nutrients excreted from the animals will be returned to the land through a soil injection system and manure spreading. Land, air, and water quality will be monitored as part of the closed nutrient system to assure environmental integrity.

Richard Gates is smiling because he safely descended from his perch (opposite page) atop the 40-foot smellstacks at the Woodford County Animal Research Center.

Richard Gates

top