BIONÆR-Bionæringsprogram

GRASS TO GAS: Mitigating GHG emissions from pasture-based sheep systems ('GrassToGas') GrassToGas will develop breeding and feeding strategies to mitigate greenhouse gas emissions (GHG) from pasture-based livestock production; these strategies must be sustainable. GrassToGas combine international expertise from scientific and commercial partners to gain knowledge and design applied solutions reducing greenhouse gas emissions in sheep, with a focus on enteric (=from the rumen) methane. GHG is an international challenge which must be met by international cooperation both in research and in application of solutions: GrassToGas is run by scientists and experts from 7 nations and 3 continents: Norway, Scotland, Ireland, France, Turkey, New Zealand and Uruguay. All are nations with substantial sheep production, and together they provide Grass-To-Gas with a wide selection of environmental conditions and many different types of sheep to be explored the project. Tailor-made and standardized measurements of methane emissions and feed uptake are necessary to be able to develop new climatic-change strategies for sheep breeding: we must be able to compare different solutions and production systems! Grass-to-gas will develop such standards through applying and comparing different sensor technologies and protocols for registrations. E.g., standardized measurements may be used to estimate individual animals’ genetic value for quantity of enteric methane, and thus enable us to select breeding stock for different environments even cross borders. Today there are no such recognized standards. At NMBU we focus on different forage and pasture qualities, and how they affect feed intake and methane emissions in different types of sheep. To measure enteric methane emissions we cooperate with the Norwegian sheep and goat breeders association, using their new lorry with 10 measurement chambers (PAC chambers) mounted. NMBU has two very different genotypes (breeds) of sheep in the flock: the old Norse, light breed, Old Norwegian Spæl Sheep (ONS, approx. 60 kg adult weight) and the dominating breed in Norway, the modern, high producing Norwegian White gram CH4 / time, mens GNS låg på Sheep (NWS, approx. 90 kg adult weight). During 2020 and 2021 we measured methane emission from the rumen of 20 ewes of each breed feeding then two silage qualities (very good and medium) in winter. The following summer the animals were fed naturally developing pasture grass (quality registered every day). Both experiments lasted six weeks. We registered the individual ewes’ continuous feed intake and measured enteric methane every second week. In the silage trial we also sampled the rumen micro flora of ewes on both forage qualities; analyses funded by Eckbo’s legate. Descriptive statistics show substantial effects of both sheep breed and forage quality. Data are still being analyzed, so far we have found that quantity of forage eaten, is strongly correlated to methane emission: a small sheep eat less and emits less methane (ONS 0.95 versus NWS 1.65 g CH4/hour), corresponding for the pasture grass trial emissions were 1,42 (GNS) and 2,13 (NKS) g methane/hour. Higher emission on grass versus silage is due to increased intake. Emission intensity (emission per kg product) is modelled, taking the higher production of NKS into account. The HolosNorSheep farm-model estimates that NKS has the lowest intensity with 16,3 CO2 equivalents whilst GNS has 21,3 CO2 equivalents (per kg carcass. Corrected for quantity of forage eaten, GNS still emit less methane (1.07 g versus 1.52 g for NWS). This indicate breed-specific genetic processes in how methane is produced in the rumen, and at a potential for utilizing the breed difference in breeding for reduced emissions. Rumen size may also be important for this and results from the Eckbo project (above), showing larger rumens relative to body size in NKS compared to GNS, indicate that digestive anatomy plays a part. We also found interesting breed differences in how forage quality affected feed intake: NWS ewes strongly increased intake from the good to the very good quality (2.5 kg versus 1.8 kg dry matter) while the ONS ewes had a much weaker response (1.3 kg versus 1.1 kg dry matter); this breed difference was also reflected in methane emission quantity. Looking at forage quality corrected for dry matter intake, the very good quality resulted in lower emission (1.28 g / hour) than the good quality (1.32 g/hour). Data from the pasture grass experiment are still being analyzed, it is already clear that emission of methane (per dry matter intake) increased with decreasing grass quality. Together with our international partners we are currently developing models for relationships btw feed intake (and other proxies) and enteric methane emissions. The models will be tested across countries and environments to establish best possible models for predicting methane emissions from different sheep genotypes across count

GrassToGas will determine appropriate breeding and nutritional management mitigation strategies to reduce GHG in pasture-based livestock systems. The overall aim of the project is to combine international scientific and industry expertise to generate new knowledge and applied solutions for the mitigation of greenhouse gas emissions (GHG) in sheep. The concept relates to the fact that the international sheep breeding community is at different stages of development in the creation of resource populations to generate feed intake and methane emission measurements for sheep. These are needed to specifically provide new breeding solutions for the sheep industry. The GrassToGas partners are using different sensor technologies, measurement protocols and approaches to address the issue of reducing GHG emissions from sheep. Combining and sharing expertise and addressing knowledge gaps through collaboration in GrassToGas will ensure that consensus on the utilisation of key measurement methods as predictors of GHG emissions, feed and forage efficiency can be agreed and adopted at an international level for use in sheep breeding programmes. As the reduction in GHG emissions is a global issue, a trans-national and trans-disciplinary (breeding, nutrition, economic) approach is necessary which will be incorporated into this project by respective partners focussing on key elements of the knowledge gap for pasture-based sheep systems.