Feb 4, 2021 | Emissions, Food & farming

Feed trees to sheep to cut greenhouse gases?

3 scottish blackface sheep in a field

It is estimated that one kilogramme of nitrous oxide warms the atmosphere about 300 times the amount than one kilogramme of carbon dioxide does over a 100-year timescale, so anything that reduces nitrous oxide emissions is worth considering seriously.

Scientists from the Game & Wildlife Conservation Trust (GWCT) monitored four groups of six Aberfield x lambs, half of which were fed around 200g of goat willow leaves each per day. When their urine patches were monitored, they found significant reductions in both nitrous oxide and carbon dioxide in those groups which fed on willow leaves. The work, part-funded by the Woodland Trust, also found lower emissions of ammonia from urine patches where lambs were fed willow.

While cutting branches to feed to livestock is labour-intensive, a move towards agroforestry with livestock (also known as silvopasture) would allow the direct browsing of coppiced trees if livestock access is managed to ensure sustainability. The use of tree fodder as an alternative source of food during periods of drought may become increasingly relevant as the climate changes, but these results suggest that a supplementary benefit of incorporating willow into grazing ruminant systems may be a contribution to climate change mitigation, as well as air quality improvement.

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