Warwick Brabazon Badgery

Context: Enteric methane (CH4) emission from livestock accounts for 71% of greenhouse gas emissions from Australian agriculture. Aims: To evaluate a range of pasture mixtures by using species with anti-methanogenic properties for their compatibility, productivity, feed quality and CH4 emission reduction potential. Methods: Two field experiments were conducted at Wagga Wagga and Cowra, New South Wales, Australia, from 2022 to 2024. In total, 33 pasture mixtures were evaluated over 3 years. Herbage was taken in spring from each pasture mix to analyse mineral composition, feed quality, plant secondary compounds and CH4 yield from in vitro fermentation. Key results: Methane yield was negatively correlated with saponins and condensed tannins. Perennial herbs, particularly plantain, had higher concentrations of condensed tannins and saponins than perennial grasses, at both sites. Overall, balansa clover was the species with the highest concentration of condensed tannins and biserrula had the highest concentration of saponins. However, plantain and biserrula lacked persistence at both sites. Chicory-based pastures were highly productive with high feed quality. Conclusions: Pasture species higher in saponins and condensed tannins have great potential to reduce enteric CH4 emissions. Pasture mixtures containing plantain and/or biserrula exhibited potential to reduce CH4 emissions, but poor persistence may limit their adoption in some environments. Implications: The study provided evidence that a number of highly productive pasture mixtures have potential to reduce CH4 emission intensity and can be deployed within extensive livestock grazing systems, allowing producers opportunity to decrease their greenhouse gas liability in emission reduction schemes.

Context: Improving the stability of legumes in grasslands in the face of variable seasonal conditions is key to mitigating risks posed by drought. Aims: We assessed the persistence of a range of legume species and cultivars in order to inform legume choice for pasture improvement and identify priority species for further development. Methods: Twenty field experiments in four series were conducted at sites with contrasting seasonal and soil characteristics in the ‘high-rainfall’ (560–920 mm long-term average) Tablelands and Monaro regions of New South Wales, Australia. Legumes were grown as pure swards and assessed periodically for seedling density, plant frequency and dry matter for up to 5 years. Key results: Legume dry matter production was positively correlated with plant frequency. However, most legumes persisted poorly at most sites, particularly on soils of lower fertility. Subterranean clover (Trifolium subterraneum) cv. Goulburn was the best performing cultivar of that species across sites on the Southern Tablelands and Monaro. Yellow serradella (Ornithopus compressus) cvv. Avila and Yellotas showed promising persistence, particularly under drought conditions. White clover (T. repens) was the most broadly adapted of the perennial legumes across a range of soils, but persistence was still inadequate at many sites. Lucerne (Medicago sativa) was approximately twice as productive as the next-most productive species when soil conditions suited its growth, but it failed to persist on acidic, low-fertility soils. Conclusions: Serradella species (yellow and French, O. sativus) and white clover, in conjunction with subterranean clover, offer the best near-term prospects for diversifying legume productivity and resilience under variable seasonal conditions in tableland environments. Implications: An increased focus on phenology and seed characteristics is suggested to improve the persistence of annual and facultative perennial legume species in grasslands. Serradella and white clover are identified as the highest priorities for cultivar development for tableland environments of south-eastern Australia.

In Australia, 71% of agricultural greenhouse gas (GHG) emissions are enteric methane (CH4), mostly produced by grazing sheep and cattle. Temperate low CH4 yielding legumes and herbs can mitigate enteric CH4 production, but system-level GHG emissions need to be considered. The aims of the study were to: (1) devise a framework to assess GHG reductions when introducing low CH4 yielding species; (2) assess mechanisms of CH4 reduction in temperate legume and herb species for Australia; (3) use a case study to demonstrate expected changes to system-level GHG emissions with the introduction of low CH4 yielding legumes; and (4) identify knowledge gaps and research priorities. Results demonstrate lowering emissions intensity (kg CO2-equivalent/kg product) is crucial to mitigate GHG emissions, but livestock productivity is also important. Several pasture species have anti-methanogenic properties, but responses often vary considerably. Of the species investigated biserrula (Biserrula pelecinus) has great potential to reduce enteric CH4 emissions, but in a case study its emission intensity was similar to subterranean clover (Trifolium subterraneum) but higher than lucerne (Medicago sativa). We conclude that there are temperate legumes and herbs with anti-methanogenic properties, and/or high productivity that could reduce total CH4 emissions and emissions intensity of ruminant livestock production. There is also great diversity in some plant genotypes that can be exploited, and this will be aided by more detailed understanding of plant secondary compounds associated with CH4 reduction. This review suggests an opportunity to formulate pasture species mixtures to achieve reduced CH4 emissions with greater or equal livestock production.

Background: Grasslands are the primary source of feed for grazing livestock, and as such, knowledge on how to best manage livestock and grasslands, through the use of spatiotemporal modelling, will assist in the long‐term management of a valuable ecosystem resource.Methods: This study was conducted over 14 months between March and April 2017 in Orange, NSW, Australia. The study evaluated sheep behaviour in relation to the presence of pasture species, environment and paddock structures, using random forest modelling, to predict sheep location under continuous high (HSR, 13 DSE ha⁻¹) and low (LSR, 7 DSE ha⁻¹) stocking rates.Results: In the LSR, significant drivers included water, shade and fence lines (p < 0.01). In the HSR, only fence lines and available biomass were found to be significant (p < 0.01). The presence of green legumes in both stocking rates often increased residency by sheep. Animals spent more time together in the LSR, suggesting that social behaviour played a larger role than pasture quantity and quality in driving grazing behaviours.Conclusions: Understanding how pasture type can influence grazing behaviours and also how animal behaviour affects pasture performance and utilisation is important in developing long‐term sustainable management strategies on a paddock scale.

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.

Overgrazing has extensively degraded Chinese grasslands. A reduction in stocking rate of 30–50% below the district averages is required to increase the profitability of livestock production and protect vital ecosystem services such as mitigation of greenhouse gases (GHG). Grazing experiments located in the desert steppe, typical steppe and alpine meadow verified the influence of stocking rate and grazing management on livestock production, grassland composition and associated ecosystem services. The desert steppe experiment found lower stocking rates of ~150 SE (where SE is sheep equivalent, which is a 50 kg animal) grazing days ha–1 (1 SE ha–1 over 150 days) enhanced botanical composition, maintained profitable lamb growth rates and reduced GHG emissions intensity. The typical steppe experiment found moderate grazing pressure of ~400 SE grazing days ha–1 (4 SE ha–1 over 100 days) maintained higher lamb growth rates, an average herbage mass >0.5 t DM ha–1 that maintained the content of Leymus chinensis above 70% and Artemisia frigida below 10% of the grassland and had the highest level of net carbon sequestration. In the alpine meadow experiment the district average stocking rate of ~16 SE ha–1 (1440 SE grazing days ha–1 over 90 days) was not too high, but extending grazing into the non-growing season had no benefit. The findings of these experiments highlight that many of the benefits to ecosystem services can be achieved with reduced stocking rates which also generate profitable levels of livestock production. In both the desert and typical steppe experiments, the results were optimal when the stocking rates were adjusted to maintain average herbage mass over summer above ~0.5 t DM ha–1, whereas herbage mass was higher with the local, conservative stocking rates in the alpine meadow.