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In Depth

Kyoto and beyond

Ewe, too, can cut greenhouse gases

Last Updated Feb. 2, 2005

Farmer Andy Forrest keeps an eye on Merino sheep during muster at Yarran station near Young, 300 kilometers west of Sydney, Australia, Friday, March 5, 2004. (Rob Griffith/AP)

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.

Andre-Denis Wright

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.

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