Measuring methane emissions from sheep Livestock farmers across the country are under increasing pressure to optimise resource use efficiency and reduce greenhouse gas (GHG) emissions, and specifically methane, from ruminant livestock production systems. DR NICOLA LAMBE, SHEEP GENETICIST, SRUC Globally, sheep release around 700 million tonnes of methane
PACs are aluminium boxes, approximately 1m long with a
into the atmosphere per year (FAOSTAT 2020).
window on the front. Twelve of these compartments are mounted on a trailer that can be towed to different locations to
Carbon calculators currently do not account for differences
measure the sheep on-site. Each compartment houses an
between individual sheep in methane production. However,
individual sheep for a short period of time (50 minutes), during
research has shown that there is variation between sheep, even
which air samples are collected and methane concentration
within a flock, in the amount of methane they produce on the
can be analysed and daily emissions predicted from each
same diet and at the same live weight. Methane emissions are
sheep.
partly under genetic control and so could be changed over time by selective breeding.
SRUC has purchased a portable set of 12 PACs, mounted on a trailer, from AgResearch in New Zealand, who have developed
Therefore, if producers are likely to be rewarded in the future
and tested the design. The aim is to use this equipment in our
for reducing (or penalised for increasing) methane emissions
research, by measuring a variety of sheep from different
from their flocks, it is even more important that we are in a
breeds and systems in the UK.
position to measure these emissions, particularly from sheep managed on typical UK grass-based systems.
So far, measurements of methane have been taken on some Scottish Blackface hoggets from our SRUC hill flock and from a
One answer to the problem could be Portable accumulation
small number of commercial breeders’ farms in England with a
chambers (PACs) which can be used to rapidly measure
variety of maternal and terminal sire breeds. Results have
methane and other gas emissions from individual sheep kept in
confirmed that methane emissions from sheep are feasible to
a variety of systems, including at pasture.
measure on-farm using PACs, under UK conditions, and there is variability between animals in methane emissions recorded by PACs that could potentially be exploited within breeding programmes. Dr Nicola Lambe from SRUC, who is coordinating the PAC research said: “There is an urgent need to mitigate greenhouse gas emissions from sheep. Despite the fact that resource efficiency and greenhouse gas emissions are global priorities, there are few examples around the world of breeding strategies being implemented in practice to directly tackle these issues in sheep.
Perspectives | Autumn 2023
