Fishy food cuts belching beasts' methane

Fishy food cuts belching beasts' methane

12th March 2003

New Scientist (Print Edition)

Adding a dash of fish oil to animal fodder could help farmers stifle the greenhouse gases wafting from their farmyards, new research shows. Switching animals from regular feed onto a diet of fishy fodder cut the amount of methane in their belches by nearly half.

Methane sources
According to the US Environmental Protection Agency,
belches from farmyard animals account for around 22 per
cent of global emissions of the greenhouse gas methane.
Volume for volume, methane traps nearly 20 times as
much heat as carbon dioxide, making it a potent contributor
to global warming.

Veerle Fievez and her colleagues at Ghent University in
Belgium gauged the potential effect of adding fish oil to
fodder by mixing it with fluid taken from the fore-stomachs
of sheep. Bacteria in the fluid normally break food down,
releasing methane. But Fievez found that adding around
four per cent fish oil slashed the bacteria's methane
production by 80 per cent.

When the oil was fed to sheep, the effect was less dramatic, but the amount of methane they burped out still fell by between 25 and 40 per cent. "The fish oil shows this very powerful suppression of methane from the animals," she says.

Healthy meat

Crucially, the team found that adding fish oil did not disrupt normal digestion, a major problem with previous attempts to suppress methane production by means of an oily diet. "That's hitherto been the biggest obstacle," says Jamie Newbold of the Rowett Research Institute in Aberdeen, Scotland, whose team is developing a powdered bacterial additive to achieve the same effect (New Scientist print edition, 15 April 2000).

Fievez and her team suspect fish oil could have other benefits too. When they examined stomach contents from sheep fed on the new diet, it proved to be much richer than usual in omega-3 fatty acids and other polyunsaturated fats that are thought to help reduce cholesterol. Their hope is that meat and other produce from animals fed on fodder laced with fish oil might also have higher levels of these "good" fats, making it healthier to eat.

Acutely aware that some fish stocks are becoming seriously depleted, Fievez says it might be possible to extract the key oils from algae or minute oil-rich crustaceans called copepods, rather than fish.

One concern with the fishy diet is that produce such as meat and milk might end up smelling of fish. Fievez and her colleagues plan to examine the fatty acid profile of the produce and test its "fishiness" on a panel of tasters.

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