Helping Hogs Smell Better
good reason that no entrepreneur has tried to market a cologne
called Eau d Sooey or Evening in the Hog House.
odors are the number one complaint people have about
concentrated hog production. But several UK researchers are trying
to eliminate those smells.
approach that is getting worldwide attention is to take the smells
of the hog house and send them sky high.
At least thats 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.
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 wont smell them. Bloodhounds
might, but not humans. Then again, bloodhounds dont complain
much about their neighbors.
Up, and Away
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?
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.
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.
the wind is blowing hard which sometimes it does in early
spring we can expect that the plume of gases from the hog
house wont 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
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.
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,
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.
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.
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 isnt 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 Cromwells 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.
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.
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.
Odors from hog production, however, dont 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 arent 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.
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.
the Black Lagoon
thats 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
Her research seeks to maintain the bacterias 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.
these researchers are successful, you may want to schedule your
next garden party or soiree at the swine facility in Woodford
Causes Hog Odors
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.
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.
is during this breakdown that smells intensify, as you could imagine.
at Woodford County Farm
swine facility at the University of Kentuckys
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
Gates is smiling because he safely descended from his perch (opposite
page) atop the 40-foot smellstacks at the Woodford County Animal