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Genetically engineered clover could cut livestock methane by 10%

June 16, 2010

[Source: TV New Zealand]

Agricultural scientists say a genetically engineered clover may be able to reduce the methane emissions from livestock such as cows and sheep by 10%.

Scientists from AgResearch and one of its subsidiaries, Grasslanz Technology Ltd, said today they can “switch on” a gene in white clover to give cows and sheep extra protein, reduce emissions of methane and nitrogen waste, and  improve animal health.

Though the state science company said in a statement that the work “may result in clovers which have not been genetically modified”,  AgResearch  scientist Jimmy Suttie said the white clover would be genetically engineered, though only with genetic material from other clover species.

“There’s a scrubby little rabbit’s foot clover which produces tannins in its leaves and stems,” he said.

Genetic material from this species could be put into white clover to trigger the same effect.

Grazing animals lose between 7% and 11% of the energy they eat because micro-organisms in their first stomach, the rumen, produce methane.

These livestock “burps” produce about 90% of the methane that makes up 43% of New Zealand’s greenhouse gas emissions, but farmers have refused to be accountable for the emissions on the grounds that there are no effective tools to control them.

Some of the ways now available for methane emissions to be mitigated – such as using maize silage or other supplementary feeds which produce less methane – are more suited to dairying than sheep and beef  farms.

AgResearch scientists  have previously shown that condensed tannins – chemical compounds that are able to bind to and protect protein being broken down early in digestion – can directly reduce methane emissions when livestock eat them in forage plants such as found in some pasture species, such as lotus, a legume. But such plants can be  difficult to establish and keep growing in grazed pastures.

Suttie, science general manager of AgResearch’s applied biotechnologies, said a GE white clover could benefit not only farmers but the environment.

“Currently white clover contains extremely low levels of tannins found only in the flowers, and if we can alter this to allow condensed tannins to accumulate to effective levels in leaves then we’ll have a major benefit.

“There is evidence that tannins can reduce methane emissions from ruminants, and this increases the importance of our work,” said Dr Suttie.

A clover which reduced gas retention in livestock could also reduce bloat sometimes seen in animals eating clover-rich pastures when pasture growth is rapid in spring.

The AgResearch announcement was criticised by New Zealand’s Green Party, which said the nation’s farmers did not  have to resort to using genetic engineering to reduce greenhouse gas emissions.

“The agricultural sector already has many options to reduce greenhouse gases, which are not a gamble like GE.

“We know lower stocking rates, limiting fertilisers and possibly selective breeding (of livestock) and nitrogen inhibiters are ways to reduce greenhouse emissions,” said Green Party co-leader Russel Norman.

Norman said there was no need to use GE organisms in the field and widespread use of GE in New Zealand would damage the “clean, green” image which underpinned agricultural exports.

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