Mitigating greenhouse gas emissions from New Zealand pasture-based livestock farm systems

Designing profitable and climate-smart farms using virtual reality

Many pastoral farmers are searching for ways to lower the carbon emission footprint that is generated by livestock. Planting trees on the farm is currently a popular option for farmers to offset their emissions yet requires knowledge of suitable tree species and locations to plant them. This paper describes a decision-support tool aimed at helping farmers to create and visualise different planting designs while balancing the objectives of sequestering carbon and maintaining farm profitability. We take an innovative approach by combining virtual reality technology with biophysical models to create an environment where the user can actively create virtual future farm scenarios. Through the creation process, the user can simultaneously balance multiple objectives including farm aesthetics, economic returns, business and environmental ambitions, and carbon emissions (net) balance. For this proof-of-concept study, we incorporate virtual reality technology in Unreal Engine, environmental and financial data, and high-resolution spatial layers from an operational 400-hectare livestock farm in New Zealand.

Substituting ryegrass-based pasture with graded levels of forage rape in the diet of lambs decreases methane emissions and increases propionate, succinate, and primary alcohols in the rumen

Feeding 100% forage rape to sheep consistently lowers methane emissions per unit of intake (CH4/DMI) compared to those fed 100% ryegrass pasture. However, forage rape is usually supplemented with other feeds, which might impact the mitigation potential provided by forage rape. The objective of this study was to determine the effect of substituting ryegrass with graded levels of forage rape in the diet of lambs on methane emissions and rumen fermentation characteristics. Seventy wether lambs (n=14/treatment) were fed a ryegrass-based pasture substituted with 0, 25, 50, 75 and 100% of forage rape (Brassica napus; FR0, FR25, FR50, FR75, FR100, respectively) on a dry matter basis. Methane emissions and dry matter intake were measured for 48 h in respiration chambers and a rumen fluid sample was collected. CH4/DMI decreased (P < 0.01) with increasing forage rape inclusion in the diet, so that sheep fed FR100 and FR75 emitted 34 % and 11% less, respectively, than those fed FR0. CH4/DMI differences for lambs fed FR25 and FR50 were much smaller (< 6%) relative to FR0. The pH of rumen fluid decreased (P < 0.01) at higher levels of forage rape inclusion in the diet (FR75 and FR100) compared to low levels of inclusion (FR0, F25 and F50). The proportion of ruminal acetate was least in FR100 (30%) followed by FR75 (10%), FR50 (8%) and FR25 (4%) compared with FR0 (P < 0.001). The proportion of propionate plus succinate was greater for FR100 (+40%), FR75 (+28%) and FR50 (+29%) compared with FR0, with FR25 intermediate (P < 0.001). The methanol concentration, and ethanol and propanol proportions in rumen fluid were greater for FR100 compared with any other treatment (P < 0.001). In conclusion, CH4/DMI decreased at high levels of forage rape inclusion in the diet and especially feeding FR100 was associated with a pronounced shift in rumen fermentation profile, with significant presence of succinate, ethanol, propanol, methanol, valerate and caproate.

Carbon myopia: The urgent need for integrated social, economic and environmental action in the livestock sector

Livestock have long been integral to food production systems, often not by choice but by need. While our knowledge of livestock greenhouse gas (GHG) emissions mitigation has evolved, the prevailing focus has been-somewhat myopically-on technology applications associated with mitigation. Here, we (1) examine the global distribution of livestock GHG emissions, (2) explore social, economic and environmental co-benefits and trade-offs associated with mitigation interventions and (3) critique approaches for quantifying GHG emissions. This review uncovered many insights. First, while GHG emissions from ruminant livestock are greatest in low- and middle-income countries (LMIC; globally, 66% of emissions are produced by Latin America and the Caribbean, East and southeast Asia and south Asia), the majority of mitigation strategies are designed for developed countries. This serious concern is heightened by the fact that 80% of growth in global meat production over the next decade will occur in LMIC. Second, few studies concurrently assess social, economic and environmental aspects of mitigation. Of the 54 interventions reviewed, only 16 had triple-bottom line benefit with medium-high mitigation potential. Third, while efforts designed to stimulate the adoption of strategies allowing both emissions reduction (ER) and carbon sequestration (CS) would achieve the greatest net emissions mitigation, CS measures have greater potential mitigation and co-benefits. The scientific community must shift attention away from the prevailing myopic lens on carbon, towards more holistic, systems-based, multi-metric approaches that carefully consider the raison d'être for livestock systems. Consequential life cycle assessments and systems-aligned 'socio-economic planetary boundaries' offer useful starting points that may uncover leverage points and cross-scale emergent properties. The derivation of harmonized, globally reconciled sustainability metrics requires iterative dialogue between stakeholders at all levels. Greater emphasis on the simultaneous characterization of multiple sustainability dimensions would help avoid situations where progress made in one area causes maladaptive outcomes in other areas.

Increasing Dairy Sustainability with Integrated Crop–Livestock Farming

Dairy farms are predominantly carbon sources, due to high livestock emissions from enteric fermentation and manure. Integrated crop–livestock systems (ICLSs) have the potential to offset these greenhouse gas (GHG) emissions, as recycling products within the farm boundaries is prioritized. Here, we quantify seasonal and annual greenhouse gas budgets of an ICLS dairy farm in Wisconsin USA using satellite remote sensing to estimate vegetation net primary productivity (NPP) and Intergovernmental Panel on Climate Change (IPCC) guidelines to calculate farm emissions. Remotely sensed annual vegetation NPP correlated well with farm harvest NPP (R2 = 0.9). As a whole, the farm was a large carbon sink, owing to natural vegetation carbon sinks and harvest products staying within the farm boundaries. Dairy cows accounted for 80% of all emissions as their feed intake dominated farm feed supply. Manure emissions (15%) were low because manure spreading was frequent throughout the year. In combination with soil conservation practices, ICLS farming provides a sustainable means of producing nutritionally valuable food while contributing to sequestration of atmospheric CO2. Here, we introduce a simple and cost-efficient way to quantify whole-farm GHG budgets, which can be used by farmers to understand their carbon footprint, and therefore may encourage management strategies to improve agricultural sustainability.