Biomass use, production, feed efficiencies, and greenhouse gas emissions from global livestock systems

Phylogenomic analysis reveals five independently evolved African forage grass clades in the genus Urochloa

BACKGROUND AND AIMS

The grass genus Urochloa (Brachiaria) sensu lato includes forage crops that are important for beef and dairy industries in tropical and sub-tropical Africa, South America and Oceania/Australia. Economically important species include U. brizantha, U. decumbens, U. humidicola, U. mutica, U. arrecta, U. trichopus, U. mosambicensis and Megathyrsus maximus, all native to the African continent. Perennial growth habits, large, fast growing palatable leaves, intra- and interspecific morphological variability, apomictic reproductive systems and frequent polyploidy are widely shared within the genus. The combination of these traits probably favoured the selection for forage domestication and weediness, but trait emergence across Urochloa cannot be modelled, as a robust phylogenetic assessment of the genus has not been conducted. We aim to produce a phylogeny for Urochloa that includes all important forage species, and identify their closest wild relatives (crop wild relatives). Finally, we will use our phylogeny and available trait data to infer the ancestral states of important forage traits across Urochloa s.l. and model the evolution of forage syndromes across the genus.

METHODS

Using a target enrichment sequencing approach (Angiosperm 353), we inferred a species-level phylogeny for Urochloa s.l., encompassing 54 species (~40 % of the genus) and outgroups. Phylogenies were inferred using a multispecies coalescent model and maximum likelihood method. We determined the phylogenetic placement of agriculturally important species and identified their closest wild relatives, or crop wild relatives, based on well-supported monophyly. Further, we mapped key traits associated with Urochloa forage crops to the species tree and estimated ancestral states for forage traits along branch lengths for continuous traits and at ancestral nodes in discrete traits.

KEY RESULTS

Agricultural species belong to five independent clades, including U. brizantha and U. decumbens lying in a previously defined species complex. Crop wild relatives were identified for these clades supporting previous sub-generic groupings in Urochloa based on morphology. Using ancestral trait estimation models, we find that five morphological traits that correlate with forage potential (perennial growth habits, culm height, leaf size, a winged rachis and large seeds) independently evolved in forage clades.

CONCLUSIONS

Urochloa s.l. is a highly diverse genus that contains numerous species with agricultural potential, including crop wild relatives that are currently underexploited. All forage species and their crop wild relatives naturally occur on the African continent and their conservation across their native distributions is essential. Genomic and phenotypic diversity in forage clade species and their wild relatives need to be better assessed both to develop conservation strategies and to exploit the diversity in the genus for improved sustainability in Urochloa cultivar production.

Interplay between Livestock Grazing and Aridity on the Ecological and Nutritional Value of Forage in Semi-arid Mediterranean Rangelands (NE Spain)

Rangeland-based livestock production constitutes a primary source of livelihood for many inhabitants of dryland regions. Their subsistence relies heavily on maintaining the productivity, biodiversity and services of these ecosystems. Harsh environmental conditions (e.g., drought) combined with land use intensification (e.g., overgrazing) make dryland ecosystems vulnerable and prone to degradation. However, the interplay between livestock grazing intensity and aridity conditions in driving the conservation and nutritional value of forage in arid and semi-arid rangelands is still not fully understood. In this study, we performed structural equation models (SEM) to assess the simultaneous direct and indirect effects of livestock grazing intensity and aridity level on community structure, diversity, biomass, forage production, forage C:N ratio and forage fiber composition in two semi-arid Mediterranean rangelands, NE Spain. Not surprisingly, we found that higher livestock grazing intensity led to lower community plant cover, especially when combined with higher aridity. However, both increasing grazing intensity and aridity were associated with higher forage production after one year of grazing exclusion. We did not find any adverse effect of livestock grazing on plant diversity, although plant species composition differed among grazing intensity levels. On the other hand, we found an aridity-driven trade-off in regard of the nutritional value of forage. Specifically, higher aridity was associated with a decrease in the least digestible fiber fraction (i.e., lignin) and an increase in forage C:N ratio. More interestingly, we found that livestock grazing modulated this trade-off by improving the overall forage nutritional value. Altogether, our results provide further insights into the management of semi-arid Mediterranean rangelands, pointing out that maintaining traditional rangeland-based livestock production may be a sustainable option as long as rangeland conservation (e.g., community plant cover) is not severely compromised.

Global nitrous oxide emissions from livestock manure during 1890-2020: An IPCC tier 2 inventory

Nitrous oxide (N2O) emissions from livestock manure contribute significantly to the growth of atmospheric N2O, a powerful greenhouse gas and dominant ozone-depleting substance. Here, we estimate global N2O emissions from livestock manure during 1890-2020 using the tier 2 approach of the 2019 Refinement to the 2006 IPCC Guidelines. Global N2O emissions from livestock manure increased by ~350% from 451 [368-556] Gg N year-1 in 1890 to 2042 [1677-2514] Gg N year-1 in 2020. These emissions contributed ~30% to the global anthropogenic N2O emissions in the decade 2010-2019. Cattle contributed the most (60%) to the increase, followed by poultry (19%), pigs (15%), and sheep and goats (6%). Regionally, South Asia, Africa, and Latin America dominated the growth in global emissions since the 1990s. Nationally, the largest emissions were found in India (329 Gg N year-1), followed by China (267 Gg N year-1), the United States (163 Gg N year-1), Brazil (129 Gg N year-1) and Pakistan (102 Gg N year-1) in the 2010s. We found a substantial impact of livestock productivity, specifically animal body weight and milk yield, on the emission trends. Furthermore, a large spread existed among different methodologies in estimates of global N2O emission from livestock manure, with our results 20%-25% lower than those based on the 2006 IPCC Guidelines. This study highlights the need for robust time-variant model parameterization and continuous improvement of emissions factors to enhance the precision of emission inventories. Additionally, urgent mitigation is required, as all available inventories indicate a rapid increase in global N2O emissions from livestock manure in recent decades.

Effect of urea-treated rice straw, mixed with faba bean straw, on nutrient digestibility, blood metabolites and performance of growing lambs

The present study aimed to use poor quality roughages, such as rice and faba bean straw, treated with or without urea, and their impacts on digestibility, rumen fermentation, some blood parameters, and growth performance of lambs. Twenty crossbred male lambs (1/4 Finland ×¾ Ossimi, 25±1.13kg live body weight) were chosen and divided into four groups. All lambs were fed rations of concentrated feed mixture at 2% of live weight with the following roughages ad libitum: URS (control group, untreated rice straw), TRS (urea-treated rice straw), FBS (faba bean straw), and TRS+FBS (mixture of TRS and FBS, 1:1). Nutrient digestibility and feeding values improved (P<0.05) with TRS+FBS lambs versus FBS, TRS and URS lambs. The highest numerical values of ruminal total volatile fatty acid (VFA) concentration in TRS lambs were recorded 23.9 ml.eq/dl followed by TRS+FBS, URS and FBS. Regarding to the ruminal parameters, there were no differences (P>0.05) among evaluated groups except for NH3-N, the highest concentration (P<0.05) was recorded in TRS lambs at 3 h post-feeding. Lambs of TRS, FBS and TRS+FBS showed faster growth (P<0.05) than those of the control (i.e., URS). Intakes of dry matter, total digestible nutrients, and digestible crude protein were numerically increased for TRS, FBS, and TRS+FBS. Feed conversion, as kg dry matter/kg gain, was improved for TRS, FBS, and TRS+FBS lambs versus URS. Daily gain of lambs increased (P<0.05) with lambs of TRS, FBS, and TRS+FBS but URS lambs showed a decrease (P<0.05) in daily gain. Feed conversion as kg dry matter intake/kg gain was improved (P<0.05) by feeding on TRS, FBS and TRS+FBS rations versus URS. The TRS+FBS lambs tended to have the highest economic efficiency versus URS, TRS and FBS lambs. It was concluded that urea-treated rice straw could be used as sole roughage or mixed with faba bean straw (1:1) in growing lambs' ration to improve their performance and economic efficiency without adversely affecting their health.The present study aimed to use poor quality roughages, such as rice and faba bean straw, treated with or without urea, and their impacts on digestibility, rumen fermentation, some blood parameters, and growth performance of lambs. Twenty crossbred male lambs (1/4 Finland ×¾ Ossimi, 25±1.13kg live body weight) were chosen and divided into four groups. All lambs were fed rations of concentrated feed mixture at 2% of live weight with the following roughages ad libitum: URS (control group, untreated rice straw), TRS (urea-treated rice straw), FBS (faba bean straw), and TRS+FBS (mixture of TRS and FBS, 1:1). Nutrient digestibility and feeding values improved (P<0.05) with TRS+FBS lambs versus FBS, TRS and URS lambs. The highest numerical values of ruminal total volatile fatty acid (VFA) concentration in TRS lambs were recorded 23.9 ml.eq/dl followed by TRS+FBS, URS and FBS. Regarding to the ruminal parameters, there were no differences (P>0.05) among evaluated groups except for NH3-N, the highest concentration (P<0.05) was recorded in TRS lambs at 3 h post-feeding. Lambs of TRS, FBS and TRS+FBS showed faster growth (P<0.05) than those of the control (i.e., URS). Intakes of dry matter, total digestible nutrients, and digestible crude protein were numerically increased for TRS, FBS, and TRS+FBS. Feed conversion, as kg dry matter/kg gain, was improved for TRS, FBS, and TRS+FBS lambs versus URS. Daily gain of lambs increased (P<0.05) with lambs of TRS, FBS, and TRS+FBS but URS lambs showed a decrease (P<0.05) in daily gain. Feed conversion as kg dry matter intake/kg gain was improved (P<0.05) by feeding on TRS, FBS and TRS+FBS rations versus URS. The TRS+FBS lambs tended to have the highest economic efficiency versus URS, TRS and FBS lambs. It was concluded that urea-treated rice straw could be used as sole roughage or mixed with faba bean straw (1:1) in growing lambs' ration to improve their performance and economic efficiency without adversely affecting their health.

Rationalising development of classification systems describing livestock production systems for disease burden analysis within the Global Burden of Animal Diseases programme

The heterogeneity that exists across the global spectrum of livestock production means that livestock productivity, efficiency, health expenditure and health outcomes vary across production systems. To ensure that burden of disease estimates are specific to the represented livestock population and people reliant upon them, livestock populations need to be systematically classified into different types of production system, reflective of the heterogeneity across production systems. This paper explores the data currently available of livestock production system classifications and animal health through a scoping review as a foundation for the development of a framework that facilitates more specific estimates of livestock disease burdens. A top-down framework to classification is outlined based on a systematic review of existing classification methods and provides a basis for simple grouping of livestock at global scale. The proposed top-down classification framework, which is dominated by commodity focus of production along with intensity of resource use, may have less relevance at the sub-national level in some jurisdictions and will need to be informed and adapted with information on how countries themselves categorize livestock and their production systems. The findings in this study provide a foundation for analysing animal health burdens across a broad level of production systems. The developed framework will fill a major gap in how livestock production and health are currently approached and analysed.

Can Grassland Rental Lead to Herders' Rotational Grazing Under the Grassland Household Responsibility System? Evidence from Pastoral Areas in Northern China

Grassland property rights privatization has alleviated the problem of 'the tragedy of the commons' but led to an unintended ecological consequence-traditional nomadic modes declination. However, with the grassland rental market formation in countries with property rights privatization, grassland rental has reshaped the pattern of grassland allocation and provided opportunities for herders to optimize their grazing modes. Based on the survey data of herders in northern China, we theoretically analyze and empirically test grassland rental's impact on herders' rotational grazing behavior under the household responsibility system. The results show that grassland rental promotes herders' rotational grazing, and the probability of individual rotational grazing is increased by 58.27%. By increasing the operated grazing grassland area and the number of grassland plots fenced, grassland rental promotes herders' grassland endowment match with the large-scale livestock activity space and the number of grazing blocks required for rotational grazing, reduces the input cost and operation difficulty required for rotational grazing, and increase herders rotational grazing probability. Grassland rental's impact on herder's rotational grazing is heterogeneous, showing the dependence of the number of plots fenced and the scale of grazing grassland. It has a higher promotion effect on herders with more plots fenced; It cannot promote the generation of herders' rotational grazing behavior when the rented grassland area fails to make the grassland operation scale reach the minimum threshold of rotational grazing. The study emphasizes the importance of developing a grassland rental market to promote the optimization of grazing modes in grassland privatization countries.

Estimation of the Carrying Capacity and Relative Stocking Density of Mongolian grasslands under various adaptation scenarios

Mongolia's vast grasslands, crucial for both environmental and economic stability, are currently facing challenges due to overgrazing, climate change, and land-use changes. Understanding and effectively managing their Carrying Capacity (CC) and Relative Stocking Density (RSD) is essential for maintaining ecological balance. This study rigorously evaluates the CC and RSD of Mongolia's grasslands through an innovative approach that integrates ecological models with socio-economic data, aimed at improving grazing management practices. Data from the National Agency for Meteorology and Environmental Monitoring validates the model, providing precise CC and RSD estimates at the Soum level from 2000 to 2019. The study reveals significant regional variations in CC: northern grasslands exhibit a high CC of 2.8 Sheep Units (SU) per hectare, contrasting with the fragile CC in some southern regions, like the Gobi Desert, where it is as low as 0.3 SU per hectare. Approximately 38.8 % of Mongolia's territory maintains a CC exceeding 1.0 SU per hectare, indicative of sustainable grasslands. In contrast, 41.7 % of the land, primarily in southern regions, shows CCs below 0.5 SU per hectare, highlighting ecosystem vulnerability. The RSD, reflecting livestock numbers relative to CC, averages 1.07, suggesting a high livestock concentration near Ulaanbaatar but a more sustainable density across 43.2 % of the country. The research also explores adaptation scenarios against desertification and degradation, as well as improving pasture accessibility, providing insights for future grassland management strategies. In conclusion, this study emphasizes the need for sustainable land management practices to balance carrying capacity and stocking rates, offering a vital tool for policymakers and stakeholders in grassland conservation.

Local government stakeholders' perceptions of potential policy actions to influence both climate change and healthy eating in Victoria: A qualitative study

ISSUE ADDRESSED

Climate change is a defining public health issue of the 21st century. Food systems are drivers of diet-related disease burden, and account for 30% of global greenhouse gas emissions. Local governments play a crucial role in improving both the healthiness and environmental sustainability of food systems, but the potential for their actions to simultaneously address these two issues is unclear. This study aimed to explore the perceptions of Australian local government stakeholders regarding policy actions simultaneously addressing healthy eating and climate change, and the influences on policy adoption.

METHODS

We conducted 11 in-depth semi-structured interviews with stakeholders from four local governments in Victoria, Australia. Data were analysed using reflexive thematic analysis. We applied Multiple Streams Theory (MST) 'problem', 'politics and 'policy' domains to explain policy adoption influences at the local government level.

RESULTS

Key influences on local government action aligned with MST elements of 'problem' (e.g., local government's existing risk reports as drivers for climate change action), 'policy' (e.g., budgetary constraints) and 'politics' (e.g., local government executive agenda). We found limited evidence of coherent policy action in the areas of community gardens, food procurement and urban land use.

CONCLUSION

Barriers to further action, such as resource constraints and competing priorities, could be overcome by better tailoring policy action areas to community needs, with the help of external partnerships and local government executive support. SO WHAT?: This study demonstrates that Victorian local stakeholders believe they are well-positioned to implement feasible and coherent interventions that address both healthy eating and climate.

Recent Advances in Enteric Methane Mitigation and the Long Road to Sustainable Ruminant Production

Mitigation of methane emission, a potent greenhouse gas, is a worldwide priority to limit global warming. A substantial part of anthropogenic methane is emitted by the livestock sector, as methane is a normal product of ruminant digestion. We present the latest developments and challenges ahead of the main efficient mitigation strategies of enteric methane production in ruminants. Numerous mitigation strategies have been developed in the last decades, from dietary manipulation and breeding to targeting of methanogens, the microbes that produce methane. The most recent advances focus on specific inhibition of key enzymes involved in methanogenesis. But these inhibitors, although efficient, are not affordable and not adapted to the extensive farming systems prevalent in low- and middle-income countries. Effective global mitigation of methane emissions from livestock should be based not only on scientific progress but also on the feasibility and accessibility of mitigation strategies.

What Is the Likely Impact of Alternative Proteins on Diet Quality, Health, and the Environment in Low- and Middle-Income Countries

Alternative protein (AP) foods are proposed to support a global protein transition. Whereas AP food innovation has been a strategy to promote consumption of protein sources with low environmental impact in high-income countries (HICs) diets, their relation to sustainable, high-quality diets in low- and middle-income countries (LMICs) remains to be established. AP foods vary in nutrient profile, processing requirements, costs, and environmental impact. Current literature regarding AP suitability in LMIC contexts is limited. This perspective examined environmental and nutritional metrics that can assess the sustainability of AP in LMICs. Current research areas needed to accurately assess environmental impacts while considering nutritional density were identified. An overview of the usability of relevant AP in both high- and low-resource settings was also explored. Metrics addressing diverse contextual synergies in LMICs, unifying nutritional, environmental, and socioeconomic considerations, were found necessary to guide the integration of AP into LMIC diets.

Herbivore exclusion stabilizes alpine grassland biomass production across spatial scales

There is growing evidence that land-use management practices such as livestock grazing can strongly impact the local diversity, functioning, and stability of grassland communities. However, whether these impacts depend on environmental condition and propagate to larger spatial scales remains unclear. Using an 8-year grassland exclosure experiment conducted at nine sites in the Tibetan Plateau covering a large precipitation gradient, we found that herbivore exclusion increased the temporal stability of alpine grassland biomass production at both the local and larger (site) spatial scales. Higher local community stability was attributed to greater stability of dominant species, whereas higher stability at the larger scale was linked to higher spatial asynchrony of productivity among local communities. Additionally, sites with higher mean annual precipitation had lower dominant species stability and lower grassland stability at both the spatial scales considered. Our study provides novel evidence that livestock grazing can impair grassland stability across spatial scales and climatic gradients.

Crop-livestock-forestry systems as a strategy for mitigating greenhouse gas emissions and enhancing the sustainability of forage-based livestock systems in the Amazon biome

Intensification of livestock systems becomes essential to meet the food demand of the growing world population, but it is important to consider the environmental impact of these systems. To assess the potential of forage-based livestock systems to offset greenhouse gas (GHG) emissions, the net carbon (C) balance of four systems in the Brazilian Amazon Biome was estimated: livestock (L) with a monoculture of Marandu palisade grass [Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster]; livestock-forestry (LF) with palisade grass intercropped with three rows of eucalyptus at 128 trees/ha; crop-livestock (CL) with soybeans and then corn + palisade grass, rotated with livestock every two years; and crop-livestock-forestry (CLF) with CL + one row of eucalyptus at 72 trees/ha. Over the four years studied, the systems with crops (CL and CLF) produced more human-edible protein than those without them (L and LF) (3010 vs. 755 kg/ha). Methane contributed the most to total GHG emissions: a mean of 85 % for L and LF and 67 % for CL and CLF. Consequently, L and LF had greater total GHG emissions (mean of 30 Mg CO2eq/ha/year). Over the four years, the system with the most negative net C balance (i.e., C storage) was LF when expressed per ha (-53.3 Mg CO2eq/ha), CLF when expressed per kg of carcass (-26 kg CO2eq/kg carcass), and LF when expressed per kg of human-edible protein (-72 kg CO2eq/kg human-edible protein). Even the L system can store C if well managed, leading to benefits such as increased meat as well as improved soil quality. Moreover, including crops and forestry in these livestock systems enhances these benefits, emphasizing the potential of integrated systems to offset GHG emissions.

Stakeholder-driven transformative adaptation is needed for climate-smart nutrition security in sub-Saharan Africa

Improving nutrition security in sub-Saharan Africa under increasing climate risks and population growth requires a strong and contextualized evidence base. Yet, to date, few studies have assessed climate-smart agriculture and nutrition security simultaneously. Here we use an integrated assessment framework (iFEED) to explore stakeholder-driven scenarios of food system transformation towards climate-smart nutrition security in Malawi, South Africa, Tanzania and Zambia. iFEED translates climate-food-emissions modelling into policy-relevant information using model output implication statements. Results show that diversifying agricultural production towards more micronutrient-rich foods is necessary to achieve an adequate population-level nutrient supply by mid-century. Agricultural areas must expand unless unprecedented rapid yield improvements are achieved. While these transformations are challenging to accomplish and often associated with increased greenhouse gas emissions, the alternative for a nutrition-secure future is to rely increasingly on imports, which would outsource emissions and be economically and politically challenging given the large import increases required.

Feed-food and land use competition of lowland and mountain dairy cow farms

Dairy cows and other ruminants contribute to human nutrition as they are able to convert feed components containing human inedible fibre concentrations (e.g. roughage and by-products from the food processing industry) into valuable animal-sourced food. A number of crops often fed to dairy cows (e.g. soy or cereals) are however potentially edible by humans too. Additionally, land used to grow dairy cattle feed may compete with crop production for human consumption. Two different methods to assess the competition between feed consumption of dairy cows and human food supply were thus refined and tested on 25 Swiss dairy farms. With respect to the potential human edibility of the feeds used in dairy production, the human-edible feed conversion ratio (eFCR) was applied. The land use ratio (LUR) was used to relate the food production potential, per area of land utilised, with the dairy production output. Low to medium eFCR, with values ranging from 0.02 to 0.68 were found, as an average proportion of 0.74 of total DM intake consisted of roughage. In contrast, we found relatively high LUR (0.69-5.93) for most farms. If the land area used to produce feed for cows was used for crop production (applying a crop rotation), 23 of the 25 farms could have produced more edible protein and all farms more human-edible energy. Indicator values strongly depend on the underlying scenarios, such as the human-edible proportion of feeds or the suitability of land and climate for crop production. Reducing the amount of human-edible feeds in dairy farming by feeding by-products from the food processing industry and improving forage quality may be suitable strategies to reduce eFCR, but relying on low-opportunity cost feeds may restrict milk performance level per cow. On farm level, improving overall efficiency and therefore using less land (especially area suitable for crop production) per kg product decreases LUR. However, the most promising strategy to mitigate land use competition may be to localise dairy production to land areas not suitable for crop production. Both methods (eFCR and LUR) should be used in parallel. They offer an opportunity to holistically evaluate the net contribution of dairy production to the human food supply under different environmental conditions and stress the importance of production systems well suited to specific farm site characteristics.

Gridded livestock density database and spatial trends for Kazakhstan

Livestock rearing is a major source of livelihood for food and income in dryland Asia. Increasing livestock density (LSKD) affects ecosystem structure and function, amplifies the effects of climate change, and facilitates disease transmission. Significant knowledge and data gaps regarding their density, spatial distribution, and changes over time exist but have not been explored beyond the county level. This is especially true regarding the unavailability of high-resolution gridded livestock data. Hence, we developed a gridded LSKD database of horses and small ruminants (i.e., sheep & goats) at high-resolution (1 km) for Kazakhstan (KZ) from 2000-2019 using vegetation proxies, climatic, socioeconomic, topographic, and proximity forcing variables through a random forest (RF) regression modeling. We found high-density livestock hotspots in the south-central and southeastern regions, whereas medium-density clusters in the northern and northwestern regions of KZ. Interestingly, population density, proximity to settlements, nighttime lights, and temperature contributed to the efficient downscaling of district-level censuses to gridded estimates. This database will benefit stakeholders, the research community, land managers, and policymakers at regional and national levels.

Enteric methane emission factors of smallholder dairy farming systems across intensification gradients in the central highlands of Ethiopia

BACKGROUND

Following global pledges to reduce greenhouse gas (GHG) emissions by 30% by 2030 compared to the baseline level of 2020, improved quantification of GHG emissions from developing countries has become crucial. However, national GHG inventories in most Sub-Saharan African countries use default (Tier I) emission factors (EFS) generated by the Intergovernmental Panel on Climate Change (IPCC) to estimate enteric CH4 emissions from animal agriculture. The present study provides an improved enteric CH4 emission estimate (Tier II) based on animal energy requirements derived from animal characteristics and performance data collected from about 2500 cattle in 480 households from three smallholder farming systems to represent the common dairy farming in the central highlands of Ethiopia. Using average seasonal feed digestibility data, we estimated daily methane production by class of animal and farming system and subsequently generated improved EF.

RESULTS

Our findings revealed that the estimated average EF and emission intensities (EI) vary significantly across farming systems. The estimated value of EF for adult dairy cows was 73, 69, and 34 kg CH4/cow/year for urban, peri-urban, and rural farming systems, respectively. Rural dairy farming had significantly higher emission intensity (EI) estimated at 1.78 CO2-eq per kg of fat protein-corrected milk (FPCM) than peri-urban and urban 0.71 and 0.64 CO2-eq kg-1 FPCM dairy farming systems, respectively. The EF estimates in this study are lower than the IPCC's (2019) default value for both stall-fed high-productive and dual-purpose low-productive cows.

CONCLUSIONS

The current findings can be used as a baseline for the national emission inventory, which can be used to quantify the effects of future interventions, potentially improving the country's commitment to reducing GHG emissions. Similarly, this study suggests that increased animal productivity through improved feed has a considerable mitigation potential for reducing enteric methane emissions in smallholder dairy farming systems in the study area.

Three main dimensions reflected by national SDG performance

Unraveling the complexity of the 17 interacting sustainable development goals (SDGs) is crucial for their achievement. Empirically revealing the dimensions of the SDGs helps generalize the dominant features of SDGs and better understand their drivers. Here, using a database of 166 countries' progress toward achieving each individual SDG, we found that about 70% of the variability of national SDG performance can be captured by three dimensions: socioeconomic development at the expense of resource and climate, the environment, and development at the expense of equality. Moreover, these dimensions are mainly affected by the economy; as gross domestic product (GDP) per capita increases, the first dimension increases monotonically, the environment dimension decreases and then increases, and the inequality dimension increases and then decreases. Our findings indicate a dim prospect of eventually achieving all SDGs because of the conflicts between economic growth and resource and climate goals under the current development paradigm, highlighting the importance of sustainable transformation.

Grazing intensity effects on rangeland condition and tree diversity in Afar, northeastern Ethiopia

This study assessed the effects of different grazing pressures (light, moderate and heavy) on rangeland condition and woody species diversity in northeastern Ethiopia. Rangeland condition was analyzed using common protocols for the assessment of semi-arid rangelands. A total of 4 grasses, 5 herbs, 1 sedge and 14 tree and/or shrub species were identified. Results show that grazing intensity had detrimental effects on condition of the rangeland, and caused undesirable changes in herbaceous species composition. The contribution of undesirable plants to herbaceous aboveground biomass was particularly high (40 %) compared to the 30 % contributed by highly desirable species. Nearly all measures of range condition were negatively affected by grazing. Grass composition, number of seedlings and age distribution, basal and litter cover, soil erosion and compaction decreased significantly as grazing intensity increased. Species richness and diversity (Hill numbers) of woody plants were reduced significantly by grazing. The overall condition of the rangeland was generally poor. The pastoralists perceived that recurring droughts, heavy continuous grazing and inappropriate management interventions, and bush encroachment were the main contributing factors that led to overgrazing and rangeland deterioration in the area. In conclusion, our study shows that livestock grazing in northeastern Ethiopia degrade range condition and woody vegetation, and its effects are sever under moderate and heavy grazing. Management measures such as resting of the rangelands preferably with stock exclusions for 6-12 months or protecting heavily degraded or sensitive areas from livestock activity and reseeding may be the viable options to mitigate declines in range conditions.

New insights in improving sustainability in meat production: opportunities and challenges

Treating livestock as senseless production machines has led to rampant depletion of natural resources, enhanced greenhouse gas emissions, gross animal welfare violations, and other ethical issues. It has essentially instigated constant scrutiny of conventional meat production by various experts and scientists. Sustainably in the meat sector is a big challenge which requires a multifaced and holistic approach. Novel tools like digitalization of the farming system and livestock market, precision livestock farming, application of remote sensing and artificial intelligence to manage production and environmental impact/GHG emission, can help in attaining sustainability in this sector. Further, improving nutrient use efficiency and recycling in feed and animal production through integration with agroecology and industrial ecology, improving individual animal and herd health by ensuring proper biosecurity measures and selective breeding, and welfare by mitigating animal stress during production are also key elements in achieving sustainability in meat production. In addition, sustainability bears a direct relationship with various social dimensions of meat production efficiency such as non-market attributes, balance between demand and consumption, market and policy failures. The present review critically examines the various aspects that significantly impact the efficiency and sustainability of meat production.

How environmental decentralization affects the synergy of pollution and carbon reduction: Evidence based on pig breeding in China

Reducing pollution and carbon is essential to achieve China's goal of "carbon peaking and carbon neutrality"; however, the collaborative paths of pollution and carbon reduction remain vague and worth exploring. This paper analyses panel data from 30 provinces in China from 2002 to 2017 to determine the impact of environmental decentralization on the synergy of pollution and carbon reduction in pig farming. The result shows that environmental decentralization has a significant 'carbon reduction effect' and 'pollution reduction effect' on pig farming; it is also conducive to promoting the synergistic effect of reducing pollution and carbon emissions through supporting environmental facilities and industrial organisations. Various types of environmental decentralization have significant differences in the synergy of pollution and carbon reduction. The scale of pig breeding plays a positive regulatory role in the impact of environmental decentralization on the synergy of pollution and carbon reduction while showing regional heterogeneity. This research is crucial for advancing the green transformation of pig breeding.

The potential consequences of grain-trade disruption on food security in the Middle East and North Africa region

The Middle East and North Africa (MENA) region has seen remarkable population growth over the last century, outpacing other global regions and resulting in an over-reliance on food imports. In consequence, it has become heavily dependent on grain imports, making it vulnerable to trade disruptions (e.g., due to the Russia-Ukraine War). Here, we quantify the importance of imported grains for dietary protein and energy, and determine the level of import reductions at which countries are threatened with severe hunger. Utilizing statistics provided by the Food and Agriculture Organization (FAO), we employed a stepwise calculation process to quantify the allocation of both locally produced and imported grains between the food and feed sectors. These calculations also enabled us to establish a connection between feed demand and production levels. Our analysis reveals that, across the MENA region, 40% of total dietary energy (1,261 kcal/capita/day) and 63% of protein (55 g/capita/day) is derived from imported grains, and could thus be jeopardized by trade disruptions. This includes 164 kcal/capita/day of energy and 11 g/capita/day of protein imported from Russia and Ukraine. If imports from these countries ceased completely, the region would thus face a severe challenge to adequately feed its population. This study emphasizes the need for proactive measures to mitigate risks and ensure a stable food and feed supply in the MENA region.

A global dataset for the production and usage of cereal residues in the period 1997-2021

Crop residue management plays an important role in determining agricultural greenhouse gas emissions and related changes in soil carbon stocks. However, no publicly-available global dataset currently exists for how crop residues are managed. Here we present such a dataset, covering the period 1997-2021, on a 0.5° resolution grid. For each grid cell we estimate the total production of residues from cereal crops, and determine the fraction of residues (i) used for livestock feed/bedding, (ii) burnt on the field, (iii) used for other off-field purposes (e.g. domestic fuel, construction or industry), and (iv) left on the field. This dataset is the first of its kind, and can be used for multiple purposes, such as global crop modelling, including the calculation of greenhouse gas inventories, estimating crop-residue availability for biofuel production or modelling livestock feed availability.

Evolutions in Commercial Meat Poultry Breeding

This paper provides a comprehensive overview of the history of commercial poultry breeding, from domestication to the development of science and commercial breeding structures. The development of breeding goals over time, from mainly focusing on production to broad goals, including bird welfare and health, robustness, environmental impact, biological efficiency and reproduction, is detailed. The paper outlines current breeding goals, including traits (e.g., on foot and leg health, contact dermatitis, gait, cardiovascular health, robustness and livability), recording techniques, their genetic basis and how trait these antagonisms, for example, between welfare and production, are managed. Novel areas like genomic selection and gut health research and their current and potential impact on breeding are highlighted. The environmental impact differences of various genotypes are explained. A future outlook shows that balanced, holistic breeding will continue to enable affordable lean animal protein to feed the world, with a focus on the welfare of the birds and a diversity of choice for the various preferences and cultures across the world.

Industrial fisheries have reversed the carbon sequestration by tuna carcasses into emissions

To limit climate warming to 2°C above preindustrial levels, most economic sectors will need a rapid transformation toward a net zero emission of CO2 . Tuna fisheries is a key food production sector that burns fossil fuel to operate but also reduces the deadfall of large-bodied fish so the capacity of this natural carbon pump to deep sea. Yet, the carbon balance of tuna populations, so the net difference between CO2 emission due to industrial exploitation and CO2 sequestration by fish deadfall after natural mortality, is still unknown. Here, by considering the dynamics of two main contrasting tuna species (Katsuwonus pelamis and Thunnus obesus) across the Pacific since the 1980s, we show that most tuna populations became CO2 sources instead of remaining natural sinks. Without considering the supply chain, the main factors associated with this shift are exploitation rate, transshipment intensity, fuel consumption, and climate change. Our study urges for a better global ocean stewardship, by curbing subsidies and limiting transshipment in remote international waters, to quickly rebuild most pelagic fish stocks above their target management reference points and reactivate a neglected carbon pump toward the deep sea as an additional Nature Climate Solution in our portfolio. Even if this potential carbon sequestration by surface unit may appear low compared to that of coastal ecosystems or tropical forests, the ocean covers a vast area and the sinking biomass of dead vertebrates can sequester carbon for around 1000 years in the deep sea. We also highlight the multiple co-benefits and trade-offs from engaging the industrial fisheries sector with carbon neutrality.

Global nitrogen deposition inputs to cropland at national scale from 1961 to 2020

Nitrogen (N) deposition is a significant nutrient input to cropland and consequently important for the evaluation of N budgets and N use efficiency (NUE) at different scales and over time. However, the spatiotemporal coverage of N deposition measurements is limited globally, whereas modeled N deposition values carry uncertainties. Here, we reviewed existing methods and related data sources for quantifying N deposition inputs to crop production on a national scale. We utilized different data sources to estimate N deposition input to crop production at national scale and compared our estimates with 14 N budget datasets, as well as measured N deposition data from observation networks in 9 countries. We created four datasets of N deposition inputs on cropland during 1961-2020 for 236 countries. These products showed good agreement for the majority of countries and can be used in the modeling and assessment of NUE at national and global scales. One of the datasets is recommended for general use in regional to global N budget and NUE estimates.

Enhanced food system efficiency is the key to China's 2060 carbon neutrality target

Bioenergy with carbon capture and storage, among other negative-emission technologies, is required for China to achieve carbon neutrality-yet it may hinder land-based Sustainable Development Goals. Using modelling and scenario analysis, we investigate how to mitigate the potential adverse impacts on the food system of ambitious bioenergy deployment in China and its trading partners. We find that producing bioenergy domestically while sticking to the food self-sufficiency ratio redlines would lower China's daily per capita calorie intake by 8% and increase domestic food prices by 23% by 2060. Removing China's food self-sufficiency ratio restrictions could halve the domestic food dilemma but risks transferring environmental burdens to other countries, whereas halving food loss and waste, shifting to healthier diets and narrowing crop yield gaps could effectively mitigate these external effects. Our results show that simultaneously achieving carbon neutrality, food security and global sustainability requires a careful combination of these measures.

Multi-model assessment identifies livestock grazing as a major contributor to variation in European Union land and water footprints

Food systems are the largest users of land and water resources worldwide. Using a multi-model approach to track food through the global trade network, we calculated the land footprint (LF) and water footprint (WF) of food consumption in the European Union (EU). We estimated the EU LF as 140-222 Mha yr^-1 and WF as 569-918 km³ yr^-1. These amounts are 5-7% of the global LF and 6-10% of the global WF of agriculture, with the EU representing 6% of the global population. We also calculated the global LF of livestock grazing, accounting only for grass eaten, to be 1,411-1,657 Mha yr^-1, and the global LF of agriculture to be 2,809-3,014 Mha yr^-1, which is about two-thirds of what the Food and Agriculture Organization Statistics (FAOSTAT) database reports. We discuss here the different methods for calculating the LF for livestock grazing, underscoring the need for a consistent methodology when monitoring the food LF and WF reduction goals set by the EU's Farm To Fork Strategy.

Changes in global food consumption increase GHG emissions despite efficiency gains along global supply chains

Greenhouse gas (GHG) emissions related to food consumption complement production-based or territorial accounts by capturing carbon leaked through trade. Here we evaluate global consumption-based food emissions between 2000 and 2019 and underlying drivers using a physical trade flow approach and structural decomposition analysis. In 2019, emissions throughout global food supply chains reached 30 ±9% of anthropogenic GHG emissions, largely triggered by beef and dairy consumption in rapidly developing countries-while per capita emissions in developed countries with a high percentage of animal-based food declined. Emissions outsourced through international food trade dominated by beef and oil crops increased by ~1 Gt CO₂ equivalent, mainly driven by increased imports by developing countries. Population growth and per capita demand increase were key drivers to the global emissions increase (+30% and +19%, respectively) while decreasing emissions intensity from land-use activities was the major factor to offset emissions growth (-39%). Climate change mitigation may depend on incentivizing consumer and producer choices to reduce emissions-intensive food products.

Organic farming offers promising mitigation potential in dairy systems without compromising economic performances

There is a lack of clear empirical evidence towards the lower carbon footprint of organic food products, in particular in the dairy sector. Until now, small sample sizes, lack of properly defined counterfactual and the omission of land-use related emissions have hindered comparisons of organic and conventional products. Here we bridge these gaps by mobilizing a uniquely large dataset of 3074 French dairy farms. Using propensity score weighting, we find that the carbon footprint of organic milk is 19% (95%CI = [10%-28%]) lower than its conventional counterpart without indirect land-use change and 11% (95%CI = [5%-17%]) lower with indirect land use changes. In both production systems, farms' profitability is similar. We simulate the consequences of the Green deal target of 25% of agricultural land devoted to organic dairy farming and show that this policy would reduce the greenhouse gas emissions of the French dairy sector by 9.01-9.64%.

Herders' adaptation strategies and animal husbandry development under climate change: A panel data analysis

The frequent occurrence of extreme climate events has become an indisputable fact. However, the role of adaptation to extreme climate change in the development of livestock husbandry is still insufficiently understood. This study empirically analyzed the impact of herders' adaptation strategies to extreme drought on livestock husbandry development and aimed to explore the optimal grassland management path under continuous climate change. A panel dataset of surveyed herders from the Xilingol League, a traditional pastoral area in China, was used. The results indicated that the average frequency of extreme drought in the Xilingol League from 1980 to 2020 was 4.94 months/year, and the occurrence of extreme drought showed a slightly upward trend. The average technical efficiency of livestock husbandry was 0.721, which can still be improved. Hay purchases can effectively promote livestock technical efficiency (p<0.01) and is the main adaptation strategy of herders to extreme drought. Further analysis showed that non-farming and pastoral employment has a positive regulatory effect in the impact of purchased hay on livestock technical efficiency. The results of this study deepen the understanding of effective adaptation to extreme weather events in pastoral areas due to climate change and provide useful information to policymakers engaged in grassland management.

Can the Middle East-North Africa region mitigate the rise of its food import dependency under climate change?

The dependence on imports of the Middle East and North Africa (MENA) region for its food needs has increased steadily since the early 1960s, from 10% to about 40%. This import dependence could continue to rise in coming decades due to the projected MENA population growth and the expected negative impacts of climate change on the region's natural resources and agricultural performances. To what extent the food import dependency of the MENA region will continue to increase up to 2050 and how the region could mitigate its rising reliance on food imports is both a key question for the region itself and a crucial geopolitical issue for the world as a whole. In this paper, we use a biomass balance model to assess the level of the food import dependency of the MENA region in 2050 resulting from six scenarios. We show that under current trends and severe impacts of climate change the food import dependency of the MENA would continue to rise and reach 50% in 2050. Maghreb would be particularly affected becoming dependent on imports for almost 70% of its food needs. Adopting a Mediterranean diet, reaching faster productivity growth in agriculture or reducing waste and loss along the food chain would contribute to decelerate the rise of the MENA's food import dependency. However, only the combination of these three options could significantly offset the increased import dependency in the most affected sub-regions: Maghreb, the Middle and the Near East. In all scenarios, Turkey strengthens its position as a net exporter of agricultural products.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10113-023-02045-y.

The global biodiversity footprint of urban consumption: A spatially explicit assessment for the city of Vienna

With ongoing global urbanization processes and consumption patterns increasingly recognized as key determinants of environmental change, a better understanding of the links between urban consumption and biodiversity loss is paramount. Here we quantify the global biodiversity footprint (BDF) of Vienna's (Austria) biomass consumption. We present a state-of-the-art product specific approach to (a) locate the production areas required for Vienna's consumption and map Vienna's BDF by (b) linking them with data taken from a previously published countryside Species-Area-Relationship (cSAR) model with a representation of land-use intensity. We found that food has the largest share in Vienna's BDF (58 %), followed by biomass for material applications (28 %) and bioenergy (13 %). The total BDF occurs predominantly within Austria and in its neighbouring countries, with ~20 % located outside Europe. Although the per capita biomass consumption in Vienna is above the global average, global and Viennese per capita BDFs are roughly equal, indicating that Vienna sources its products from high-yield regions with efficient production systems and comparatively low native species richness. We conclude that, among others, dietary changes offer a key leverage point for reducing the urban BDF, while expanding the use of biomass for material and energy use may increase the BDF and requires appropriate monitoring.

Micro- and Macro-Algae Combination as a Novel Alternative Ruminant Feed with Methane-Mitigation Potential

This study was conducted to provide alternative high-quality feed and to reduce methane production using a mixture of the minimum effective levels of Euglena gracilis, EG, and Asparagopsis taxiformis, AT. This study was performed as a 24 h in vitro batch culture. Chemical analysis demonstrated that EG is a highly nutritive material with 26.1% protein and 17.7% fat. The results showed that the supplementation of AT as a feed additive at 1 and 2.5% of the diet reduced methane production by 21 and 80%, respectively, while the inclusion of EG in the diet at 10 and 25% through partially replacing the concentrate mixture reduced methane production by 4 and 11%, respectively, with no adverse effects on fermentation parameters. The mixtures of AT 1% with both EG 10% and EG 25% had a greater reductive potential than the individual supplementation of these algae in decreasing methane yield by 29.9% and 40.0%, respectively, without adverse impacts on ruminal fermentation characteristics. These results revealed that the new feed formulation had a synergistic effect in reducing methane emissions. Thus, this approach could provide a new strategy for a sustainable animal production industry.

Evaluation of a Model (RUMINANT) for Prediction of DMI and CH4 from Tropical Beef Cattle

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.

Evaluation of global Cenchrus germplasm for key nutritional and silage quality traits

Cenchrus is important genera of grasses inhabiting tropical pastures and the Indian grasslands system. Its forage value is well established to sustain nomadic livestock and wildlife. This study deals with the evaluation of the representative set of global Cenchrus germplasm collection with 79 accessions belonging to six species (C. ciliaris, C. setigerus, C. echinatus, C. myosuroides, C. pennisetiformis, and C. biflorus) at flowering stage. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose, and lignin values were in the range of 61.1-136, 640-749, 373-490, 277-375, and 35.6-75.50 g kg-1DM, respectively, while sugar contents varied from 11.6 to 101 mg g-1 DM. From the evaluated germplasm, 14 accessions of C. ciliaris having >70 mg g-1 DM sugar contents were selected and further evaluated for protein, fiber, carbohydrate and protein fractions, palatability indices, in vitro CH4 production, and ensiling traits. Protein contents were lower in EC397323 (61.8) and higher in IG96-96 (91.5), while the NDF, ADF, cellulose, and lignin contents varied between 678-783, 446-528, 331-405, and 39.6-62.0 g kg-1DM, respectively. The carbohydrate and protein fractions of selected accessions differed (p < 0.05), and the sugar contents varied (p < 0.05) between 74.6 and 89.6 mg-1g DM. Dry matter intake (DMI) and relative feed value (RFV) of accessions varied (p < 0.05) and were in the range of 1.53-1.77% and 58.2-73.8 g kg-1 DM, respectively. The total digestible nutrients (TDNs), digestible energy (DE), and metabolizable energy (ME) of selected accessions varied between 362-487 g kg-1 DM, 6.62-8.90, and 5.42-7.29 Mj kg-1 DM, respectively. In vitro gas and CH4 production (24 h) varied (p < 0.05) between 73.1 to 146 and 7.72 to 21.5 ml/g, respectively, while the degraded dry matter (g kg-1 DM) and CH4 (ml/g DDM) ranged between 399-579 and 17.4-47.2, respectively. The DM contents at ensiling, silage pH, and lactic acid contents of accessions differed (p < 0.05) and ranged between 185-345 g kg-1 DM, 5.10-6.05, and 1.39-23.3 g kg-1 DM, respectively. Wide genetic diversity existed in germplasm and selected C. ciliaris accessions for protein fiber, energy, sugar, and other nutritional traits. Silage prepared from EC397366, IG96-96, IG96-50, and EC397323 had pH and lactic acid contents acceptable for moderate to good quality silage of tropical range grasses.

Friend or Foe? The Role of Animal-Source Foods in Healthy and Environmentally Sustainable Diets

Scientific and political discussions around the role of animal-source foods (ASFs) in healthy and environmentally sustainable diets are often polarizing. To bring clarity to this important topic, we critically reviewed the evidence on the health and environmental benefits and risks of ASFs, focusing on primary trade-offs and tensions, and summarized the evidence on alternative proteins and protein-rich foods. ASFs are rich in bioavailable nutrients commonly lacking globally and can make important contributions to food and nutrition security. Many populations in Sub-Saharan Africa and South Asia could benefit from increased consumption of ASFs through improved nutrient intakes and reduced undernutrition. Where consumption is high, processed meat should be limited, and red meat and saturated fat should be moderated to lower noncommunicable disease risk-this could also have cobenefits for environmental sustainability. ASF production generally has a large environmental impact; yet, when produced at the appropriate scale and in accordance with local ecosystems and contexts, ASFs can play an important role in circular and diverse agroecosystems that, in certain circumstances, can help restore biodiversity and degraded land and mitigate greenhouse gas emissions from food production. The amount and type of ASF that is healthy and environmentally sustainable will depend on the local context and health priorities and will change over time as populations develop, nutritional concerns evolve, and alternative foods from new technologies become more available and acceptable. Efforts by governments and civil society organizations to increase or decrease ASF consumption should be considered in light of the nutritional and environmental needs and risks in the local context and, importantly, integrally involve the local stakeholders impacted by any changes. Policies, programs, and incentives are needed to ensure best practices in production, curb excess consumption where high, and sustainably increase consumption where low.

Beyond pastures, look at plastic: Using Sentinel-2 imagery to map silage bags to improve understanding of cattle intensity

Cattle ranching has increased globally in the last decades, and although pasture expansion is well documented across different regions, there is little understanding of the intensity at which cattle operate in these areas. With freely available Sentinel-2 satellite imagery, we mapped for the first time polyethylene silage bags used for forage conservation in a year with the Random Forest algorithm, and proposed them as a spatial indicator of cattle intensity. For this, we combined monthly silage area with land cover and climatic variables in a regression framework to understand cattle intensity metrics at regional and farm scales throughout 20 million hectares in the Dry Chaco. In addition, we explored the impact of using maize silage supplementation on productive and environmental metrics at the farm scale in a precipitation gradient. We validated our models using a spatially explicit database of cattle distribution. Our results highlight that silage bags are accurate mappable objects with Sentinel-2, which can contribute to the understanding of cattle density, and heifer and steer density in pasture contexts at farm and regional scales. Finally, our whole-farm simulations support the idea that incorporating silage supplementation in cattle ranching regional analyses conducts to significant differences on environmental or productive estimations, which should be considered. The amount of stored forage that is used in supplementation has strong implications for the performance of cattle ranching, but remains difficult to quantify at the regional level with remote sensing. Silage bag mapping is thus an opportunity to improve the overall understanding of livestock intensification and its productive and environmental impacts, particularly in highly seasonal rangelands. Following this metric could be a valuable indicator of the cattle ranching performance in terms of it resilience, production increase and impacts over natural ecosystems (related to Sustainable Development Goal 2-zero hunger and also in the 15-life on land).

Effect of planting and mowing cover crops as livestock feed on soil quality and pear production

INTRODUCTION

The increasing demand for animal-products has led to an increasing demand for livestock feed. Using cover crop as green manure in orchards is an effective measure to improve fruit yield and quality. However, the effect of mowing cover forage crops as livestock feed on soil quality and crop production is unclear.

METHOD

Therefore, a 4-year field experiment, which included two treatments, was conducted in pear orchards in Luniao County, China: natural grass (NG) and planting and mowing forage crop ryegrass as livestock feed (MF).

RESULTS

Under MF treatment, most soil nutrient content, especially alkalihydrolysable N (AN), total phosphate (TP), available phosphate (AP), and microbial biomass phosphate (MBP), had decreased significantly (P<0.05), while β-D-glucosidase (BG, C-cycle enzyme) and soil C limitation at 10-20 cm depth and P limitation at subsoil (20-40 cm) was increased. In addition, the soil bacterial community component in topsoil (0-10 cm and 10-20 cm) and fungal community component in topsoil and subsoil were changed in the MF treatment. Network analysis showed that MF treatment had a lower edge number in topsoil but the community edge numbers increased from 12794 in NG to 13676 in MF in subsoil. The average weight degree of the three soil layers in MF treatment were reduced, but the modularity had increased than that in NG. For crop production, MF treatment was 1.39 times higher in pear yield and titratable acids (AC) reduced from 0.19% to 0.13% compared with NG. These changes were more associated with the indicators at the subsoil, especially for TP, AN, pH, and F-NMDS1 (non-metric multidimensional scaling (NMDS) axis 1 of fungi).

DISCUSSION

These results provide data support for the feasibility of planting and mowing forage crops as livestock feed on orchards as well as a new idea for the integration of crop and livestock.

Co-benefits assessment of integrated livestock and cropland system based on emergy, carbon footprint and economic return

The rapid specialization of livestock production contributes to spatially decoupled crop and livestock production. Relinking croplands and livestock to promote wastes and by-products exchange has been suggested to provide opportunities for sustainable intensification of agriculture systems. However, the environmental and economic performances of such crop-livestock systems remain highly context specific and unclear. This study proposed an emergy-LCA-based framework to study the GHG mitigation and ecological and economic benefits of the integrated crop planting and livestock feeding systems, by taking wheat maize rotation-swine systems (WMRS), tea-swine systems (TS) and citrus alfalfa intercropping-swine systems (CAIS) as the empirical cases. The results showed the three case modes can generally promote GHG mitigation and ecological and economic benefits. CAIS had the lowest carbon footprint per kcal product (0.12 g CO₂-eq kcal^-1), followed by TS (0.61 g CO₂-eq kcal^-1) and MWRS (0.66 g CO₂-eq kcal^-1). The significant difference in this indicator can be attributed to their different upstream input and manure management. Due to the lower dependence on purchased resources, CAIS also had the best performance on emergy-based sustainability and economic benefits. Based on our results, the policy implications, including promoting wastes and by-products exchange, choosing reasonable manure treatment mode and conducting systematic planning have been suggested to provide opportunities for GHG mitigation and sustainable intensification of agro-systems.

Responses of grassland productivity to mowing intensity and precipitation variability in a temperate steppe

Mowing for hay is an important land use in grasslands that is affected by precipitation variability, due to the water-limited nature of these ecosystems. Past land use and precipitation conditions can have legacy effects on ecosystem functions, potentially altering responses to both mowing and precipitation. Nonetheless, it is still unclear how natural variation in precipitation will affect plant responses to changes in mowing intensity. We conducted a seven-year field experiment with three mowing intensity treatments compared to the traditional mowing intensity (5 cm stubble height) as a control: increased mowing (2 cm stubble), decreased mowing (8 cm stubble) and ceased mowing. Decreased mowing increased both plant aboveground net primary productivity [ANPP] and forage yield across the whole community, driven by increases in graminoids, mainly owing to the positive response of plants to precipitation. Both mowing disturbance and precipitation variability had legacy effects on plant ANPP; however, these responses differed among the whole community, graminoid, and forb levels. Current-year community-wide ANPP [ANPP_n] was positively associated with current-year precipitation [PPT_n] in all mowing treatments, driven by positive precipitation responses of the dominant graminoids. For forbs, however, ANPP_n was negatively associated with prior-year growing season precipitation [PPT_n-1] across mowing treatments, potentially due to lagged competition with the dominant graminoids. Our results suggest that the response of the dominant graminoids is the primary factor determining the response of ANPP to mowing and precipitation variability in these grassland ecosystems, and highlight that decreasing mowing intensity may maximize both herder's income and grassland sustainability.

Associations of daily diet-related greenhouse gas emissions with the incidence and mortality of chronic diseases: a systematic review and meta-analysis of epidemiological studies

OBJECTIVES

Although the entire process extending from food production to dietary consumption makes a large contribution to total greenhouse gas (GHG) emissions, little and inconsistent evidence exists on the epidemiological associations of daily diet-related GHG emissions with chronic disease risk or all-cause mortality. This systematic review and meta-analysis explored the observational epidemiological relationship between daily diet-related GHG emissions and health outcomes, including the risk of chronic diseases and all-cause mortality.

METHODS

Original articles published in English until May 2022 were identified by searching PubMed, Ovid-Embase, Web of Science, CINAHL, and Google Scholar. The extracted data were pooled using both fixed-effects and random-effects meta-analyses and presented as hazard and risk ratios (RRs) with 95% confidence intervals (CIs).

RESULTS

In total, 7 cohort studies (21 study arms) were included for qualitative synthesis and meta-analysis. The GHG emissions of dietary consumption showed a significant positive association with the risk of chronic disease incidence and mortality in both fixed-effects and random-effects models (fixed: RR, 1.04; 95% CI, 1.03 to 1.05; random: RR, 1.04; 95% CI, 1.02 to 1.06). This positive association was robust regardless of how daily diet-related GHG emissions were grouped. More strongly animal- based diets showed higher GHG emissions. However, there were only a few studies on specific chronic diseases, and the subgroup analysis showed insignificant results. There was no evidence of publication bias among the studies (Egger test: p=0.79).

CONCLUSIONS

A higher GHG-emission diet was found to be associated with a greater risk of all-cause mortality.

Climate-friendly and nutrition-sensitive interventions can close the global dietary nutrient gap while reducing GHG emissions

Sustainable food systems require malnutrition and climate change to be addressed in parallel. Here, we estimate the non-CO₂ greenhouse gas emissions resulting from closing the world's dietary nutrient gap-that between country-level nutrient supply and population requirements-for energy, protein, iron, zinc, vitamin A, vitamin B12 and folate under five climate-friendly intervention scenarios in 2030. We show that improving crop and livestock productivity and halving food loss and waste can close the nutrient gap with up to 42% lower emissions (3.03 Gt CO₂eq yr^-1) compared with business-as-usual supply patterns with a persistent nutrient gap (5.48 Gt CO₂eq yr^-1). Increased production and trade of vegetables, eggs, and roots and tubers can close the nutrient gap with the lowest emissions in most countries-with ≤23% increase in total caloric production required for 2030 relative to 2015. We conclude that the world's nutrient gap could be closed without exceeding global climate targets and without drastic changes to national food baskets.

Embodied HANPP of feed and animal products: Tracing pressure on ecosystems along trilateral livestock supply chains 1986-2013

The global livestock system puts increasing pressures on ecosystems. Studies analyzing the ecological impacts of livestock supply chains often explain this pressure by the increasing demand for animal products. Food regime theory proposes a more nuanced perspective: it explains livestock-related pressures on ecosystems by systemic changes along the supply chains of feed and animal products, notably the liberalization of agricultural trade. This study proposes a framework supporting empirical analyses of such claims by differentiating several steps of livestock supply chains. We reconstructed "trilateral" livestock supply chains linking feed production, livestock farming, and final consumption, based on the global flows of 161 feed and 13 animal products between 222 countries from 1986 to 2013. We used the embodied Human Appropriation of Net Primary Production (eHANPP) indicator to quantify pressures on ecosystems linked to these trilateral livestock supply chains. We find that livestock induced 65 % of agriculture's pressure on ecosystems, mostly through cattle grazing. Between 1986 and 2013, the fraction of livestock-related eHANPP that was traded internationally doubled from 7.1 % to 15.6 %. eHANPP related to the trade of feed was mostly linked to soybean imported for pig meat production, whereas eHANPP associated to traded animal products was mostly linked to cattle meat. eHANPP of traded animal products was lower but increased faster than eHANPP of feed trade. eHANPP was highest at the feed production level in South and North America, and at the consumption level in Eastern Asia. In Northern Asia and Eastern Europe, eHANPP was lowest at the animal products production level. In Western Europe, the eHANPP was equal at the animal products production and consumption levels. Our findings suggest that options to reduce livestock's pressures on ecosystems exist at all levels of the supply chain, especially by reducing the production and consumption in high-consuming countries and regulating international supply chains.

The cost of diversity in livestock feed rations

This study investigates the financial cost of increasing the diversity of cereal grains in livestock feed rations. We first develop a nonlinear mathematical programming model that determines the least-cost composition of livestock feed rations of one metric ton that have at least the same energy and nutrient content as a reference feed ration. We then add into the model a diversity constraint using the Simpson Index of diversity to examine how changes in the diversity of the commodities in the ration affect the cost of the ration while maintaining the ration's energy and nutrient content at a reference ration value. We apply the model to cereal grain feed rations for livestock in 153 countries, using reference rations that depict the historical composition of cereal grain feed rations offered to livestock in each country. Results suggest that a one percent change in ration diversity changed the ration cost (i.e., the cost-diversity elasticity) from -0.67% to 1.41% (average = -0.02%) across all countries. Our results suggest that changes in ration diversity can come at a financial cost, but this financial cost appears negligible in many countries. This negligible cost could provide the feed sector more encouragement to diversify its feed supply and potentially become more resilient to price and production shocks.

The spatiotemporal patterns and network characteristics of emissions embodied in the international trade of livestock products

Livestock production is greenhouse gas (GHG) emission intensive, and thus the increasing international trade of livestock products in recent decades has resulted in increased embodied emissions. Considering the varying emission intensity in production in different countries and the expected further increase in livestock product trade in the future, it becomes crucial to understand the spatial and temporal dynamics of such embodied GHG emissions for climate change mitigation in the livestock sector. In this study, we aimed to address such gaps and analyzed the spatiotemporal patterns and network characteristics of GHG emissions embodied in the international trade of seven major categories of livestock products among 228 world economies during 1986-2017. The results showed that the total volume of GHG emissions embodied in livestock product trade reached 92.0 MT in 2017, accounting for 2.6% of the total emissions from livestock production. Sheep meat has replaced cattle meat as the major contributor to embodied emissions. In 2017, the largest flows of embodied emissions were within Europe, followed by the flows from Oceania to Asia. The fluxes in intra-upper middle and intra-high-income economies accounted for most of the total embodied emissions. Although the global average emission intensity of livestock production declined in these four decades, the trade flows from high to low emission intensity economies increased, especially for cattle and sheep meat. This resulted in an overall increase of contribution from the global livestock trade in GHG emissions from the global livestock sector. Therefore, effective measures and policies must be designed from both consumption and production perspectives to ensure proper accounting of these embodied emissions and maximize the reduction potential for a sustainable food system transition.

Agroecological practices in combination with healthy diets can help meet EU food system policy targets

Agroecology has been proposed as a strategy to improve food system sustainability, but has also been criticised for using land inefficiently. We compared five explorative storylines, developed in a stakeholder process, for future food systems in the EU to 2050. We modelled a range of biophysical (e.g., land use and food production), environmental (e.g., greenhouse gas emissions) and social indicators, and potential for regional food self-sufficiency, and investigated the economic policy needed to reach these futures by 2050. Two contrasting storylines for upscaling agroecological practices emerged. In one, agroecology was implemented to produce high-value products serving high-income consumers through trade but, despite 40% of agricultural area being under organic management, only two out of eight EU environmental policy targets were met. As diets followed current trends in this storyline, there were few improvements in environmental indicators compared with the current situation, despite large-scale implementation of agroecological farming practices. This suggests that large-scale implementation of agroecological practices without concurrent changes on the demand side could aggravate existing environmental pressures. However, our second agroecological storyline showed that if large-scale diffusion of agroecological farming practices were implemented alongside drastic dietary change and waste reductions, major improvements on environmental indicators could be achieved and all relevant EU policy targets met. An alternative storyline comprising sustainable intensification in combination with dietary change and waste reductions was efficient in meeting targets related to climate, biodiversity, ammonia emissions, and use of antibiotics, but did not meet targets for reductions in pesticide and fertiliser use. These results confirm the importance of dietary change for food system climate change mitigation. Economic modelling showed a need for drastic changes in consumer preferences towards more plant-based, agroecological and local foods, and for improvements in technology, for these storylines to be realised, as very high taxes and tariffs would otherwise be needed.

Global pastureland use as reflected in inter-regional supply chain

Pastureland used for livestock grazing is globally much bigger than arable land. This study investigates the pastureland use embedded in global supply chains by using multi-regional systems input-output anlysis, tracing embodied pastureland use from source of exploitation to sink of final consumption in the global economy. The world's pastureland resources is shown reallocated through the supply chain mainly to the four major economies: EU, the United States, China, and Japan. These four economies are responsible for driving more than half of the global pastureland exploitation. Major supply chains responsible for the global reallocation of pastureland use include the cattle supply chain from Other Asia & Pacific to the United States, China, and Japan, and the cattle supply chain from Africa to EU and the Middle East. This paper demonstrates the nature and scale of the global reallocation of pastureland resources through the supply chain, highlighting the fact that the global shift of pastureland use from nature-based to economic-based may exacerbate ecological inequity between world regions. It is proposed that future policies and regulations should encourage sustainability goals not only on a regional level but on a global scale, finding pathways to sustainable and equitable livestock production by inter-regional collaboration.