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Ruminant nutrition regimes to reduce methane and nitrogen emissions: A meta-analysis of current databases – United Kingdom

DairyCo teamed up with the UK Beef levy funded organisation, EBLEX, to undertake this important project that made effective use of existing data from the UK, the Netherlands and the USA.

As a foundation for further research to develop new ruminant nutrition regimes for simultaneously reducing methane emissions and nitrogen excretion in growing and lactating ruminants, a meta analysis was undertaken.

The outputs of this meta-analysis provided an important platform for a Government funded study investigating new ruminant diets that emit less methane via the digestive process. DairyCo was actively involved to ensure that key messages could be transferred to the dairy farmer at the earliest opportunity.

Project completed: March 2011

Main outcomes

  • Increasing maize silage in ruminant diets reduces methane emissions per kg feed DM consumed compared to feeding a grass silage based ration. These differences may reflect differences in the degradability of the carbohydrate fractions of the forages fed.
  • The use of high sugar grass varieties reduced methane emissions in sheep by circa 20% and appears to have the porential to reduce nitrogen excretion in manure and increases the efficiency of dietary nitrogen utilisation.
  • Allicin (organosulfur compound obtained from garlic) decreased methane production per unit of live weight gain in sheep by 20%. However in cows Allicin had no effect on methane excretion, although methane excreted per kg feed, dry matter intake was numerically reduced. Allicin did impart considerable taint to the milk produced. The lack of an effect of Allicin on methane production in lactating dairy cows compared to sheep may reflect differences in rumen dynamics and ecology.
  • Glycerol had no effects on milk production or methane production in dairy cows.
  • In sheep, linseed oil and naked oats decreased methane emissions by 22 and 33% respectively. In dairy cattle, feeding naked oats reduced methane excretion and the amount of methane produced per unit feed consumed or milk produced (10 and 12% reductions, respectively). This would be expected based on the fat content of the oats fed and is in line with other studies showing effects of feeding fat on methane production by ruminants.