Reducing sheep methane emissions: sustainability in practice via new breeding goals

Can sheep breeding be crucial in combating climate change? The answer is indeed yes! This is because sheep produce methane, a greenhouse gas contributing to global warming. What if we could breed sheep that emit less methane? That's the core idea behind the "Sustain Sheep" project. In this international collaborative project, researchers from different countries (Ireland, the United Kingdom, New Zealand, France, Norway, and Uruguay) engage in advanced technology known as Portable Accumulation Chambers (PAC) – mobile respiration chambers – to measure methane emissions from sheep. Through these measurements, they aim to delve into the genetics behind methane emissions and feed efficiency. The outcome will lead to recommendations for new breeding goals for sheep to reduce their carbon footprint. The potential and costs associated with implementing these breeding goals will also be thoroughly assessed. In Norway, data from the Sheep Recording System and a genomic reference population will be utilized to analyze the genetics of methane emissions in sheep. Additionally, machine learning will be applied to uncover the relationship between sheep weight, feed intake, and methane emissions. The effectiveness of selecting sheep for lower methane emissions will be further examined using a simulation model, a so-called digital twin, of the Norwegian sheep breeding program. Finally, the impact of breeding for reduced methane emissions from sheep on emissions per kilogram of carcass produced will be calculated using a whole-farm model. The effect on national greenhouse gas emissions will also be evaluated.

Breeding can be a cost-effective way of reducing enteric methane (CH4) emissions from sheep, by direct selection for CH4 emissions or indirectly through improved productivity. Currently there is under-adoption of these measures as benefits are not captured by the market. Sustain Sheep builds on the successful Joint Call ERA-Net project Grass To Gas and will create infrastructure for incorporation of low environmental impact into national breeding schemes that dovetails into the IPCC inventory. Sustain Sheep is unique as all partner countries (Ireland, United Kingdom, New Zealand, France, Norway and Uruguay) have invested in the same CH4 measurement technology (Portable Accumulation Chambers). Sustain Sheep will 1) review the current scientific status of the potential to breed sheep for reduced CH4 emissions (WP1), 2) investigate genetics of CH4 emission and feed efficiency and model the mitigation potential from breeding and give recommendations for new breeding goals (WP2), 3) forecast uptake rates, cost and abatement of breeding for reduced CH4 emissions (WP3) and 4) determine the best mechanism for dissemination and implementation of project result to maximize stakeholder involvement (WP4). In Norway, genetic and genomic analyses of data from the Norwegian Sheep Recording System and the genomic reference population recorded for CH4 emission will be done by NSG (WP2.1). Machine learning to investigate relationships between GHG emission, ewe live weight and feed intake will be applied and validated by NMBU (WP2.2). The expected response to selection for breeding goals including enteric CH4 and/or feed efficiency will be predicted by NMBU using a digital twin of the Norwegian sheep breeding scheme and data from WP2.1, and the effect on emission intensities (kg CO2-equivalents per kg product) will be investigated using a whole-farm model. The impact of alternative breeding goals on GHG emissions at national level will be quantified using IPCC methodology (WP2.3).