We present a unique, biologically consistent, spatially disaggregated global livestock dataset containing information on biomass use, production, feed efficiency, excretion, and greenhouse gas emissions for 28 regions, 8 livestock production systems, 4 animal species (cattle, small ruminants, pigs, and poultry), and 3 livestock products (milk, meat, and eggs). The dataset contains over 50 new global maps containing high-resolution information for understanding the multiple roles (biophysical, economic, social) that livestock can play in different parts of the world. The dataset highlights: (i) feed efficiency as a key driver of productivity, resource use, and greenhouse gas emission intensities, with vast differences between production systems and animal products; (ii) the importance of grasslands as a global resource, supplying almost 50% of biomass for animals while continuing to be at the epicentre of land conversion processes; and (iii) the importance of mixed crop-livestock systems, producing the greater part of animal production (over 60%) in both the developed and the developing world. These data provide critical information for developing targeted, sustainable solutions for the livestock sector and its widely ranging contribution to the global food system. global change | sustainability | GHG emissions | land use T he importance of the livestock sector as a user of natural resources, as a source of livelihoods, and as an engine of economic growth has been the focus of significant attention in the last decade (1-5). As the largest land-use system on Earth, the livestock sector occupies 30% of the world's ice-free surface, contributes 40% of global agricultural gross domestic product, and provides income for more than 1.3 billion people and nourishment for at least 800 million food-insecure people, all the while using vast areas of rangelands, one-third of the freshwater, and one-third of global cropland as feed. In the process, livestock can both contribute valuable nutrients for crops and be responsible for nutrient pollution and land degradation, and they can both provide critically important protein and micronutrients to human diets and contribute to obesity. The sector has many dualities, and the roles played by livestock change depending on location and circumstances. However, there is growing recognition that improving the environmental performance of livestock systems as well as establishing sustainable levels of consumption of animal-sourced foods, are essential for the sustainability of the global food system (5-7).Insufficient attention has been paid to the generation of livestock data at the level of detail required for elucidating their future role in attaining key global sustainability goals. Some of these goals are poverty reduction, food and nutritional security, ecosystem protection, mitigation of greenhouse gases (GHG), and adaptation to climate change, for example. To date, global integrated assessments have included incomplete representations, at best, of the livestock sector (8-11). So...

Abstract. A method for gravimetric determination of tannins based on binding with insoluble polyvinylpyrrolidone (PVP) is presented. The gravimetric method gives the absolute amount of tannins and avoids problems of standards associated with spectrophotometric methods. The method was applied to nine browse and tree leaves. The values obtained correlate significantly with tannins determined spectrophotometrically, protein precipitation capacities and protein precipitable phenolics. This method together with other tannin assays will be useful in nutritional studies. The present study also demonstrates the different behaviour of tannic acids from different commercial sources towards PVP suggesting the presence of different moieties in tannic acids from different commercial sources and even among batches from the same source thereby affecting the results obtained using the spectrophotometric methods. Use of well-defined tannic acid as a standard in spectrophotometric methods is suggested which will allow meaningful comparison of values obtained from different laboratories.

Various tannin-complexing agents have been used to study the potential adverse effects of tannins on rumen metabolism. Using a method based on turbidity formation, the binding of various tannincomplexing agents (polyvinyl polypyrrolidone (PVPP), polyethylene glycol (PEG) of molecular weights 2000 to 35000, and polyvinyl pyrrolidme (PVP) of molecular weight 10000, 40000 and 360000) to tannins (tannic acid, purified tannins from quebracho (Aspidosperma quebracho) and leaves of trees and shrubs (Acioa barteri, Dichostachys cinerea, Guiera senegalensis, Piliostigma reticulatum)) was investigated at different pH values. The binding of all the tannins with PVPP was highest at pH 3 4 and lowest at pH 7. For all the pH range (3-7) studied, the binding of PEG was higher than that of PVP. For all the tannins except tannic acid, the binding to PVP was the same from pH 4.7 to 7. Similar results were observed for the PEG of molecular weight 6OOO or higher for all the tannins except quebracho tannins for which the binding increased as the pH increased from 3 to 7. The binding with PEG 2000 decreased to a greater extent as the pH reached near neutral and for PEG 4000 this decrease was slightly lower. Addition of these tannin-complexing agents to the in vitro gas system resulted in higher gas production from tannin-rich feeds (increase varied from 0 to 135%). The PEG were the most effective followed by P V P and PVPP. The PEG 35000 was least effective. The efficiency of other PEG was similar. The PEG 6000 was preferred to PEG 2000 or 4000 as its binding to tannins was higher at near neutral pH values. The gas production increased with an increase in the amount of PEG 6OOO up to 0.6 g/40 ml rumen-fluid-containing medium containing 0.5 g tannin-rich feed, beyond which no increase was observed. The percentage increase in gas value at 24 h fermentation correlated significantly with tannin values, the highest correlation (r 0.95) being with protein precipitation capacity of tannins. The increase in gas production was associated with higher production of shortchain fatty acids with little change in their molar proportions, suggesting an increase in organic matter digestibility by inclusion of the PEG in tannin-rich feeds. However, apparent and true digestibilities were lower on addition of the PEG, due to the presence of PEGtannin complexes in the residues. The use of this bioassay (percentage increase in gas production in the presence of PEG 6000) along with other tannin assays would provide a better insight into the nutritional significance of tannins.

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Summary The stoichiometrical relationship between gas volumes and short chain fatty acid (SCFA) production has been exemplified for an in vitro gas test based on the bicarbonate buffer. It is outlined that, even though variation in the molar proportion of acetate, propionate and butyrate will influence gas volumes, quite similar amounts of total carbon, hydrogen and oxygen are required for widely different SCFA patterns (0.748: 0.194: 0.058 or 0.459: 0.462: 0.079 for C2: C3: C4), namely, 2.20–2.34 mg to produce 1 ml of gas. However, the variation in microbial biomass production per mole adenosine triphosphate (ATP) presents a serious limitation for in vitro gas tests, since these tests reflect SCFA production only. As a consequence in vitro gas tests need to be complemented by a quantification of substrate concomitantly truly degraded to avoid selection of a substrate with proportionally higher SCFA production and lower microbial biomass yield. This intrinsic problem of in vitro gas tests was experimentally demonstrated for 61 roughages, where a gravimetric determination of microbial biomass yield showed a highly significant (r = −0.78, p < 0.0001) negative relationship between microbial biomass and gas volumes in vitro when both were related to 100 mg of substrates truly degraded. The relationship was further examined for 35 roughages, being representative of the 61 samples, using incubations with stable isotopie nitrogen (15N). In these studies, 15N incorporation and gas production were significantly (r = −0.78, p < 0.001) inversely related. An in vitro method is proposed which combines gas volume and substrate degradability measurements to estimate microbial yield and these estimations agreed well (r = 0.82, p < 0.0001) with 15N measurements. Zusammenfassung Die stöchiometrischen Zusammenhänge von Gas ‐und kurzkettiger Fettsäuren ‐ Produktion im Bikarbonat gepufferten in vitro Gastest wurden exemplarisch dargestellt. Es wird gezeigt, daß unterschiedliche molare Anteile von Essig ‐, Propion ‐ und Buttersäure zwar Auswirkungen auf das Gasvolumen haben, die Masse an Kohlen‐, Wasser‐und Sauerstoff, die für 1 ml Gas nötig ist, jedoch für unterschiedliche molare Fettsäurenzusammensetzung (0.748: 0.194: 0.058 oder 0.459: 0.462: 0.079 für C2: C3: C4) mit 2.20 bis 2.34 mg sehr ähnlich ist. Unterschiedliche mikrobielle Biomasse‐Bildung per mol Adenosintriphosphat (ATP) begrenzt jedoch die Aussagefähigkeit des Gastests, da dieser nur die Bildung von kurzkettigen Fettsäuren reflektiert. In vitro Gastests bedürfen der begleitenden Quantifizierung der Menge an wahr abgebauter Substanz, um die Selektion von Substraten zu vermeiden, die eine proportional hohe kurzkettige Fettsäuren‐Produktion aber niedrigere mikrobielle Biomasse‐Bildung aufweisen. Diese Beziehung wurde experimentell für 61 Rauhfuttermittel aufgezeigt. Die gravimetrisch bestimmte mikrobielle Biomasse zeigt, bezogen auf 100 mg wahr abgebaute Substanz, eine hoch negative Beziehung (r = −0.78, p < 0.0001) zwischen diesem Parameter und dem Gasvolumen. Diese Bezieh...

The relationship between in vilro gas prodaction, concomitant in v h apparent and true DM degradability has been examined in forty-two roughages. The partitioning of truly-degraded substrate between gas volume and microbial biomass yield and "N incorporation into cells was also investigated. The relevance of this partitioning for the regulation of DM intake (DMI) was examined for my-four roughages. The results can be summarized as follows. I n vitro gas production and in vifro apparent and true degradability are highly correlated (P

The rate of fermentation of hay was not affected by purified tannins from Quercus incana and Dichostachys cinerea at 0.13 mg ml-' of the in uitro medium whereas a decrease of 4% in the rate was observed for Acioa barmi tannins at this level. At 0.23 mg and 0.47 mg of tannins per ml, the decrease in rate varied from 4 to 13% and 13 to 20%, respectively. The decrease in in uitro true digestibility of dry matter was 3, 6 and 7% for Q incana, D cinerea and A barteri, respectively, at a tannin concentration of 0.47 mg ml-', and 17, 21 and 27%, respectively, at 0.93 mg ml-'. There was no change in the potential extent of digestion up to 0.47 mg ml-' for any of the tannins studied. These results suggested that the rate of digestion is affected to a greater extent than the potential extent of digestion or the in oitro true digestibility and that different tannins even at the same level have different degrees of effect. Tannin-saponin interactions were studied using tannic acid (TA), quebracho tannin (QT) and quillaja saponin (S) at different concentrations (0.2, 0.4 and 0.6 mg ml-') alone and in combination with each other. The decrease in the rate of digestion and true digestibility was additive when both the TA and the S were present. Similar results were obtained when TA was replaced by QT except that the effects with QT were more marked as compared to TA at the same concentration. Saponins had little effect on the potential extent of digestion and true digestibility. These tannins also decreased the production of short-chain fatty acid (SCFA) and their molar proportions (acetate decreased whereas propionate increased). Efficiency of microbial protein synthesis, expressed as the ratio of ' ' N incorporation per unit of SCFA production, was higher with both S and the tannins studied. A substantial amount (71-93%) of tannins soluble in aqueous acetone was released from leaves of some trees and shrubs on incubation in the in oitro medium for 48 h. The rumen liquor was not capable of degrading oligomeric condensed tannins.

As global demand for livestock products (such as meat, milk and eggs) is expected to double by 2050, necessary increases to future production must be reconciled with negative environmental impacts that livestock cause. This paper describes the LivestockPlus concept and demonstrates how the sowing of improved forages can lead to the sustainable intensification of mixed crop-forage-livestock-tree systems in the tropics by producing multiple social, economic and environmental benefits. Sustainable intensification not only improves the productivity of tropical forage-based systems but also reduces the ecological footprint of livestock production and generates a diversity of ecosystem services (ES) such as improved soil quality and reduced erosion, sedimentation and greenhouse gas (GHG) emissions. Integrating improved grass and legume forages into mixed production systems (crop-livestock, tree-livestock, crop-tree-livestock) can restore degraded lands and enhance system resilience to drought and waterlogging associated with climate change. When properly managed tropical forages accumulate large amounts of carbon in soil, fix atmospheric nitrogen (legumes), inhibit nitrification in soil and reduce nitrous oxide emissions (grasses), and reduce GHG emissions per unit livestock product.The LivestockPlus concept is defined as the sustainable intensification of forage-based systems, which is based on 3 interrelated intensification processes: genetic intensification -the development and use of superior grass and legume www.tropicalgrasslands.info cultivars for increased livestock productivity; ecological intensification -the development and application of improved farm and natural resource management practices; and socio-economic intensification -the improvement of local and national institutions and policies, which enable refinements of technologies and support their enduring use. Increases in livestock productivity will require coordinated efforts to develop supportive government, non-government organization and private sector policies that foster investments and fair market compensation for both the products and ES provided. Effective research-for-development efforts that promote agricultural and environmental benefits of foragebased systems can contribute towards implemention of LivestockPlus across a variety of geographic, political and socio-economic contexts. ResumenDe la misma manera que la demanda global de productos pecuarios (carne, leche, huevos) se duplicará para 2050, se espera que las producciones futuras tengan en cuenta los efectos ambientales negativos ocasionados por este sector. En este documento se describe el concepto LivestockPlus y se demuestra cómo en el trópico los forrajes mejorados pueden llevar a la intensificación sostenible de sistemas de producción mixta que integran forrajes/ganadería y cultivos y/o árboles, produciendo múltiples beneficios sociales, económicos y ambientales. La intensificación sostenible no sólo incrementa la productividad de los sistemas tropicales basados en forra...