The aim of this research was to evaluate dietary inclusion of Leucaena diversifolia into a grass monoculture (GM) diet and its influence on enteric methane emissions, animal live weight gain and meat fatty acid content of steers. Two GM diets comprised Urochloa hybrid cv. Cayman or U. brizantha cv. Toledo; silvopastoral (SPS) mixed diets included an association of either grass with L. diversifolia in a 74:26 (grass:legume) planting ratio. The experiment was conducted over 16 months with 14 Brahman x Angus crossbred steers (374±7.5 kg body weight), divided into two diet groups. Steers were weighed periodically during the experiment, and methane emissions were quantified with the polytunnel technique. The meat quality and fatty acid profile were measured after slaughtering the steers. Energy density, total and digestible dry matter intake and crude protein were higher in steers fed SPS than GM (P≤0.05). At the end of the experiment, animals from SPS weighed on average 63 kg more than animals offered GM (535 vs. 472 kg; P=0.025). Net methane emitted by steers offered SPS was 142 g per day, this is equivalent to 15% less than emissions from animals that were offered GM (168 g; P=0.007). The meat fatty acid profile was similar between diets, except for cervoniv-DHA and omega-6: omega-3 ratio, which were higher in steers consuming GM diet (P≤0.05). The results of this study suggest that the inclusion of L. diversifolia improves nutrient intake, increases animal productivity, reduces daily enteric methane emission, and decreases the omega-6: omega-3 ratio in meat.

The Intergovernmental Panel on Climate Change (IPCC) provides the reference for national greenhouse gas emission (GHG) inventories towards standardized, accurate, measurable, and comparable National Inventory Reports (NIR). For compliance with the 1.5⁰C commitments under the Paris Agreement, most countries have made efforts to improve their inventory methods to tier 2 or 3. However, some relevant activities within Latin American and the Caribbean (LAC) countries, such as enteric methane emissions and methane and nitrous oxide emissions from cattle manure management are still estimated using tier 1 methods, which leads to a high uncertainty due to the importance of livestock emissions in the national totals for these countries. In this context, reducing the uncertainty in GHG inventories would not only improve the accuracy of national reports but it would also provide solid baselines for national mitigation initiatives e.g., Nationally Determined Contributions under the Paris Agreement, and accurate tools to venture into carbon bonds or payments for ecosystem services. The aim of this study was to review the status of national GHG inventories specifically for these three cattle emission categories in 11 LAC countries. We conducted a survey of GHG inventory experts in the 11 LAC countries, to identify the potential for improvement and the main barriers to achieving this. Despite some initiatives, there is still a large potential for reducing the uncertainty in LAC national GHG emission estimates, the barriers to or solutions can be categorized as technical, policy, and institutional issues. However, improving the GHG inventories of LAC countries, specifically for cattle emissions, is feasible in the medium term, as long as multilateral actions are considered, coherently linked under a comparable and verifiable methodology and including a commitment by countries to invest public funds in relevant research and innovations.

Simulation models represent a low-cost approach to evaluating agricultural systems. In the current study, the precision and accuracy of the RUMINANT model to predict dry matter intake (DMI) and methane emissions from beef cattle fed tropical diets (characteristic of Colombia) was assessed. Feed intake (DMI) and methane emissions were measured in Brahman steers housed in polytunnels and fed six forage diets. In addition, DMI and methane emissions were predicted by the RUMINANT model. The model’s predictive capability was measured on the basis of precision: coefficients of variation (CV%) and determination (R², percentage of variance accounted for by the model), and model efficiency (ME) and accuracy: the simulated/observed ratio (S/O ratio) and slope and mean bias (MB%). In addition, combined measurements of accuracy and precision were carried out by means of mean square prediction error (MSPE) and correlation correspondence coefficient (CCC) and their components. The predictive capability of the RUMINANT model to simulate DMI resulted as valuable for mean S/O ratio (1.07), MB% (2.23%), CV% (17%), R² (0.886), ME (0.809), CCC (0.869). However, for methane emission simulations, the model substantially underestimated methane emissions (mean S/O ratio = 0.697, MB% = −30.5%), and ME and CCC were −0.431 and 0.485, respectively. In addition, a subset of data corresponding to diets with Leucaena was not observed to have a linear relationship between the observed and simulated values. It is suggested that this may be related to anti-methanogenic factors characteristic of Leucaena, which were not accounted for by the model. This study contributes to improving national inventories of greenhouse gases from the livestock of tropical countries.

This article offers a critical approach towards adopting new technologies as a mitigation strategy. It provides a comprehensive analysis that helps illuminate the adoption process and the sociocultural factors intersecting and informing it. Using a capability approach lens and qualitative and participatory data collection methods, this study presents and analyses the testimonies of smallholders living on Colombia’s Pacific coast, currently exposed to a series of interventions that promote changes in production decisions to contribute to reducing national greenhouse gas emissions. Specifically, improved forages, silvopastoral systems and new practices, such as the implementation of rotational pasturing, have been promoted as relevant new approaches. The results show that access to new technologies generates new capabilities, for instance the ability to plan for the challenges imposed by climate change or to develop new strategies to allow the soil to recover naturally. However, these new possibilities are unevenly distributed, creating disadvantages for groups that generally experience conditions of vulnerability, such as young farmers and women. The testimonies also show that many of the promoted initiatives emphasise the need for adaptation and change on the part of smallholders without considering the limitations of technology, the gender issues that affect the inclusion of women and the dynamics that set barriers to young smallholders due to economic restrictions or power issues. Therefore, the study contends that, when understanding technology adoption, it is not only a question of what farmers do or do not do but of what they can be and do in increasingly demanding contexts.