Researcher Measures the Gases Cows Emit
By KATHLEEN HENNESSEY
Associated Press Writer
Wed Jul 27, 9:51 PM ET

DAVIS, Calif. - In a white, tent-like "bio-bubble" on
a farm near Davis, eight pregnant Holsteins are
eating, chewing and pooping — for science. "The
ladies," as they're called by University of California
researcher Frank Mitloehner, are doing their part to
answer a question plaguing one of California's largest
agricultural industries: How much gas does a cow emit?

The findings will be used to write the state's first
air quality regulations for dairies and could affect
regulations nationwide.

But before he explains how it works, Mitloehner wants
one thing to be clear.

"We're not talking about flatulence," he says.

He emphasizes the point because his research has been
dismissed as "fart science," a label he says doesn't
do justice to the seriousness of his work.

There are more than 3 million cows in California, the
vast majority living in the booming Central Valley,
home to some of the most polluted air in the country.
How much to blame the cows and how much to blame the
cars for the bad air is no small concern.

Mitloehner's research has suggested that cows are
responsible for far fewer of the compounds that
contribute to smog, known as volatile organic
compounds or VOCs, than previously thought, perhaps as
little as half the amount.

That puts the air quality specialist and animal
emissions expert in the middle of a heated dispute
coming to a head Aug. 1, when the San Joaquin Valley
Air Pollution Control District will announce its new
emissions factor for cows_ the amount of VOCs, in
pounds, that a cow releases each year. The number will
eventually determine which dairies must apply for air
quality permits and invest in mitigating air pollution
equipment.

"This is a multibillion decision," said Mitloehner.
"It's not just a number."

Currently, regulators assume that a cow produces 12.8
pounds of VOCs a year.

But regulators, environmentalists and many in the $4
billion dairy industry agree that the current emission
factor, which is based on a 1938 study, is out of
date.

A regulator for the air control district has proposed
an increase to 20.6 pounds per cow. Industry groups
estimate that number is around 5 pounds.

Mitloehner says he just wants to make sure the new
number is based on science.

His solution was to recreate a cow's living conditions
in a modern dairy and then seal it off.

In one experiment, eight cows spend two days in the
space-agey, air-conditioned "bio-bubble." The large
white structure houses a typical dry-lot corral,
blanketed with dirt and, by the end of the experiment,
manure. The cows are left to eat, chew and emit
compounds while their every move is caught on video
and the air is monitored by machines so sensitive they
can detect one molecule out of a trillion others.

A similar test is conducted in a smaller environmental
chamber simulating a typical stall with a concrete
floor.

To Mitloehner's surprise, the first results from that
study show the presence of smog-causing compounds
dropped significantly after the cows left chamber,
even though they left fresh manure behind.

"We thought it was the waste that would lead to the
majority of emissions, but it seemed to have been the
animals," he said.

The chief offender appears to be the ruminating
process. After a cow eats, the food is briefly
deposited in its bathtub-sized stomach. There it mixes
with bacteria, begins to break down and produces
methane, a greenhouse gas. About 20 minutes later, the
food comes up again as cud. As the cow chews it, the
methane is released into the air. The process also
emits methanol and ethanol, both VOCs.

For some in the industry, the results indicate that
dairy farmers who may be forced to mitigate pollution
may be trying to fight nature.

"Is this something that we really want to do, try to
regulate a living thing?" said J.P. Cativiela, a
program coordinator for Dairy CARES, an
industry-funded environmental group. "All living
things have emissions, plants, animals, even, people.
It absolutely makes sense to regulate the industrial
part of a dairy, are we really seriously talking about
regulating animals?"

Cativiela said changing a cow's food may prove to be
more effective than expensive technologies. He and
other industry advocates are concerned that regulators
will call for expanded use of methane digesters. The
digesters cover a dairy's lagoon of diluted waste,
trap pollutants and create electricity. They also cost
about $1 million a piece, and industry groups argue
their effectiveness is unproven.

Meanwhile, environmentalists contend that the import
of Mitloehner's research has been exaggerated. They
note that it tests only one of the many polluters on a
modern, large-scale dairy.

"It doesn't take into account the lagoons that store
the waste or the decomposing feed, the decomposing
corn stored on a dairy," said Brent Newell, an
attorney with the Center on Race, Poverty and the
Environment.

San Joaquin regulators say Mitloehner's research is
just one factor in the decision.

"The district's assessment is based on all of the
science in total," said spokeswoman Jaime Holt. "It is
not based on any one study, or any one process being
measured."

Mitloehner agrees that his research should only be one
of several factors being considered by regulators. But
he's recently criticized the other studies being used
by regulators, as well as how the district, which
funded part of his research, is interpreting his
findings.

He and other scientists have written letters to San
Joaquin Air Pollution Control Officer David Crow
expressing their concerns.

But for now, Mitloehner has returned to his
bio-bubbles to continue researching other cow-related
air quality problems, like dust and ammonia.

Someday, he and his students joke, he may like to use
the bio-bubble to measure emissions from another
polluter: the car.