Scientists are using water balloons to measure sheep burps as part of research into methane emissions.
At the crown research institute AgResearch, scientist Kirsty Hammond is studying how different factors affect how much of the gas animals produce.
About one-third of New Zealand's greenhouse gas emissions come from methane.
Miss Hammond, 24, said scientists were puzzled by why animals produced different amounts of methane. Most of this is produced out of their mouths, not through farting as is commonly perceived.
Methane is produced as food is broken down in the animal's gut. Miss Hammond is looking at whether less methane is produced if food spends less time in the gut.
A sheep's gut can hold about four or five litres, and Miss Hammond has placed one-litre water balloons in their stomachs.
The water balloon does not affect how much the sheep eat, but means that food passes through their stomachs faster.
Miss Hammond measures how much methane is emitted by the sheep while they are in a large respiration tank.
"It's like a four-star hotel. They go in, they're quite happy. They can see, they have got room to move."
The team uses "fistulated" sheep, which have a plug in their sides to enable scientists to insert the water balloon.
Hans Kriek, the spokesman for animal welfare group SAFE, said sheep needed major surgery in the process of having the plug installed, and could find the process of being away from a flock during research very stressful.
He said that, instead of subjecting livestock to research to reduce methane emissions, people needed to reduce their reliance on livestock.
Simone Hoskin, who heads the ruminant nutrition and greenhouse gas emission team at AgResearch, said Miss Hammond's research was world-leading and would help scientists to understand what factors affected methane production.
Understanding how the size of a gut affected digestion would tie in with Miss Hammond's research into how different foods produced different amounts of methane.
Grass, white clover and chicory all appeared to lead to different levels of methane being produced by sheep.
However, scientists would have a better understanding of the extent that they altered gas production when they knew more about the effects of other factors.
Reasons To Reduce
Why scientists are trying to reduce methane emissions:
New Zealand has about 11 million cattle and 35 million sheep.
They produce methane, a harmful greenhouse gas.
Methane contributes to global warming as it traps heat and stops it escaping from the Earth's atmosphere.
Methane emissions make up a greater part of New Zealand's greenhouse gas emissions than any other developed country.
An average herd of 360 cows loses enough energy in methane emissions each year to power a car for 300,000km.
If animals emit less methane, they will have more energy to put into producing milk and growing.
New Zealand is the only country to include agricultural emissions in its emissions trading scheme, so reducing emissions will mean lower costs for farmers.
- The Dominion Post
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