INDEPTH: KYOTO
Ewe, too,
can cut greenhouse gases
CBC News
Online | February 02, 2005
In some cultures, a good belch after a hearty meal is seen as a compliment. You've
enjoyed your meal and your body is thanking your hosts.
In places like Australia, a series of post-meal burps is a
problem, especially if you're one of 120 million sheep or 30 million head
of cattle that call the continent home. The animal burps are full of
methane gas.
Bacteria in the
intestines of the animals break down the food they eat, converting some of
it to methane gas. Ruminants – or cud-chewing animals like sheep, goats,
camels, water buffalo and cattle – eat hay and grass, which are high in
cellulose. The material is not easy to digest – the animals have to rely on
microbes that live in their guts to help in the digestion process. A
byproduct of that is about six or seven per cent of what the microbes eat
winds up as methane.
That's a
problem. It's believed that methane gas is the second-biggest contributor,
behind carbon dioxide, to the "greenhouse effect." Methane breaks
down in the atmosphere to form carbon dioxide, ozone and water, all of
which absorb heat and lead to global warming.
Those quietly
grazing sheep you see on your Sunday drive through the country are busy
passing about 20-30 litres of methane each a day
– or seven kilograms a year – just by digesting their food. That's 10 times
what the average person expels fulfilling their daily nutritional needs.
The numbers are
even worse when it comes to cattle. Cattle will emit between 200 and 300 litres of methane each every day. Multiply that by the
1.2 billion head of cattle that call this planet home, and you've got a lot
of gas.
Researchers have
found that the amount of methane produced by cattle varies dramatically
according to the quality of its diet. Animals that eat poorer quality meal
– which is more common in warmer climates – produce significantly more gas
and less meat and milk. Better diets, on the other hand, mean better
production from the animals – and a little less gas passed through
breathing and burping.
In Australia, animal gas is a huge problem.
With 120 million sheep and 28 million head of cattle, ruminants were
responsible for 12.3 per cent of the country's greenhouse gas emissions in
2002.
In a country as
vast as Australia, where sheep and cattle get much
of their food from the open range, making subtle changes to an animal's
diet can be a tall order.
Enter
Andre-Denis Wright, a Canadian, originally from Halifax. He
did his post-graduate work at the University of Guelph in Ontario, earning a PhD.
You might say
Wright's consumed by what goes on in the insides of sheep and cattle. His
research eventually caught the eye of CSIRO, Australia's Commonwealth Scientific and
Industrial Research Organisation.
He figured if
ruminants expended less energy digesting their food, their bodies could
redirect that energy into growth and milk production. He began working on a
vaccine designed to help ruminants spend less energy processing their food.
But there was an
unexpected side-effect as well. Those bigger, meatier sheep were passing
less methane gas.
"Originally,
we were looking at increasing the efficiency of the digestion of ruminant
animals," Wright told CBC News Online. "But we discovered that we
could reduce methane emissions as well. We killed two birds with one
stone."
Wright's team
came up with an oral vaccine that's administered once a year. Farmers don't
have to spend a lot of time tracking down their animals over huge expanses
of land to medicate them.
So far, the
evidence suggests the cut in emissions is no minor blip.
"We
achieved a 10 per cent reduction in methane production by targeting only 20
per cent of the microbes [in the digestive tract] that lead to methane
production," Wright said.
"If we cut
emissions from ruminants by 20 per cent, it would decrease all greenhouse
gas emissions in Australia by three per cent."
Hitting that
target would go a long way toward meeting Australia's commitments under the Kyoto protocol.
No wonder scientists
around the world are taking notice. In July 2004, Wright presented his
research at a conference in France, attended by 270 scientists from
35 countries.
In Canada, cattle produce about 19 megatonnes of greenhouse gas emissions per year – or about three
per cent of the country's total. But that estimate is based on data from
other countries. Environment Canada wants to find out whether the diet
of Canadian cattle produces different numbers.
In the spring of
2004, the agency gave Professor Karin Wittenberg, the head of animal
science at the University of Manitoba, $50,000 to study the connection
between how cattle in this country digest their food and methane
production.
The research
will help fuel Canada's drive to get a more accurate
estimate on bovine-burp methane. It's a requirement under the country's
participation in the United Nations Framework Convention on Climate Change.
In Alberta, methane emission from ruminants
is expected to hit the equivalent of 8.6 megatonnes
of CO2 by 2008-2012. That's an increase of 38 per cent from 1990 levels –
mostly due to growth in the number of feeder cattle, dairy cattle, hogs,
poultry, bison, elk and deer in the province.
It also means
that if no action is taken before that, Alberta would have to cut emissions by 40
per cent in 2010 to meet Kyoto commitments. Another reason a
Canadian studying the inner workings of sheep in Australia is attracting a lot of attention.
|