Assessing the environmental impact of ruminant production systems

Agriculture, Ecosystems & Environment

López-Aizpún

Blackwell

et al. 2020

Highlights Urinary nitrogen concentrations were lowest on animals consuming high sugar grasses. However, soil under high sugar grasses recorded the highest N 2 O emissions. Synthetic urine generated N 2 O emissions inconsistent with locally collected urine. Differences in emissions amongst systems were explained by gene abundance ratios. Results indicate the importance of soil-pasture-animal-microbiome interactions.

Section: Discussionsupporting

confidence: 88%

Elucidating three-way interactions between soil, pasture and animals that regulate nitrous oxide emissions from temperate grazing systems

Agriculture, Ecosystems & Environment

López-Aizpún

Blackwell

et al. 2020

“…Y m , was investigated in isolation as it has been shown to account for ∼50% or more (pending uncertainties) of total GWP 100 carbon footprints of grassland beef systems in the UK (McAuliffe et al 2018 ). Further, these three coefficients were chosen for exploration as they have previously been shown to be the most important drivers of emissions’ uncertainty for beef production systems (Takahashi et al 2019 ).…”

Section: Methodsmentioning

confidence: 99%

Are single global warming potential impact assessments adequate for carbon footprints of agri-food systems?

Lynch

Cain

et al. 2023

Environ. Res. Lett.

Self Cite

The vast majority of agri-food climate-based sustainability analyses use GWP100 as an impact assessment, usually in isolation; however, in recent years, discussions have criticised the ‘across-the-board’ application of GWP100 in Life Cycle Assessments (LCA), particularly of food systems which generate large amounts of methane (CH4) and considered whether reporting additional and/or alternative metrics may be more applicable to certain circumstances or research questions. This paper reports a sensitivity analysis using a pasture-based beef production system (a producer of high CH4 emissions) as an exemplar to compare various climate impact assessments: CO2-equivalents using GWP100 and GTP100, and ‘CO2-warming-equivalents’ using ‘GWP Star’, or GWP*. The inventory for this system was compiled using data from the UK Research and Innovation (UKRI) National Capability, the North Wyke Farm Platform, in Devon, SW England. LCAs can have an important bearing on: (i) policymakers’ decisions; (ii) farmer management decisions; (iii) consumers’ purchasing habits; and (iv) wider perceptions of whether certain activities can be considered ‘sustainable’ or not; it is, therefore, the responsibility of LCA practitioners and scientists to ensure that subjective decisions are tested as robustly as possible through appropriate sensitivity and uncertainty analyses. We demonstrate herein that the choice of climate impact assessment has dramatic effects on interpretation, with GWP100 and GTP100 producing substantially different results due to their different treatments of CH4 in the context of carbon dioxide (CO2) equivalents. Given its dynamic nature and previously proven strong correspondence with climate models, out of the three assessments covered, GWP* provides the most complete coverage of the temporal evolution of temperature change for different GHG emissions. We extend previous discussions on the limitations of static emission metrics and encourage LCA practitioners to consider due care and attention where additional information or dynamic approaches may prove superior, scientifically speaking, particularly in cases of decision support.

“…The respective carbon footprint per unit of RDI (kg CO 2 -eq/% RDI) was derived as the ratio between RDI units delivered each year (based on a mean 68.5% meat yield per carcass weight) and mass-based carbon footprints of the three systems (21.2, 22.6 and 23.5 kg CO 2 -eq/kg final liveweight for GWC, PP and MG, respectively). These carbon footprint values encompass previously defined greenhouse gas emissions attributable to the suckler enterprise (27.1 kg CO 2 -eq/kg weaning weight: Takahashi et al, 2019 ) as well as respective finishing enterprises (16.0, 18.5 and 20.2 CO 2 -eq/kg postweaning liveweight gain for GWC, PP and MG, respectively: McAuliffe et al, 2018b ). These ratios were calculated on an individual animal basis and then averaged per year within each system.…”

Section: Methodsmentioning

confidence: 99%

Nutritional value of suckler beef from temperate pasture systems

Lee

Tweed

et al. 2021

Animal

The role of beef in human diets has been questioned over the last few decades, due largely to its typically high mass-based carbon footprint. However, recent advancements in sustainability literature challenge this paradigm based on the new theory that climate impacts of food commodities should be measured relative to their overall nutritional value rather than their nominal mass. This shift has opened a new opportunity for the global beef industry, and especially for pasture-based systems that can avoid food-feed competition for land and other resources, as beef is a nutritionally dense food. Nonetheless, the sector’s true capability to supply a wide range of nutrients for humans, consistently across multiple systems under multiple weather patterns, has not been well-documented. Using whole-system datasets from the North Wyke Farm Platform in the South West of England, we investigated the nutritional value of beef produced from the three most common pasture systems in temperate regions: permanent pasture ( PP ), grass and white clover ( GWC ) and a short-term monoculture grass ley ( MG ). Beef produced from these three pasture systems was analysed for key nutrients (fatty acids, minerals and vitamin E) over three production cycles (2015–2017) to determine potential differences between systems. Fatty acid, mineral and vitamin E profiles of the pasture and silage fed to each group were also assessed, with subtle differences between pastures reported. For beef, subtle differences were also observed between systems, with GWC having higher omega-6 polyunsaturated fatty acid ( PUFA ) concentrations than PP and MG. However, the overall nutritional quality of beef was found to be largely comparable across all systems, suggesting that temperate pasture-based beef can be classified as a single commodity in future sustainability assessments, regardless of specific sward types. A 100 g serving of temperate pasture-based beef was found to be a high source (>20% recommended daily intake: RDI ) of protein, monounsaturated fatty acids, saturated fatty acids, vitamins – B2, B3, B12 and minerals – Fe, P, Zn; a good source (10–19% RDI) of vitamin – B6 and mineral – K; and a complementary source (5–9% RDI) of omega-3 PUFA, vitamin – B9 and minerals – Cu, Mg, Se. The nutritional value of a food item should be used in defining its environmental cost (e.g. carbon footprint) to make fair comparisons across different food groups (e.g. protein sources). Here, we showed that pasture-based beef had a nutrient indexed carbon footprint of between 0.19 and 0.23 Kg CO2-eq/1% RDI of key nutrients.