Enteric methane (CH
4) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH
4 is complex, expensive, and impractical at large scales; therefore, models are commonly used to predict CH
4 production. However, building robust prediction models requires extensive data from animals under different management systems worldwide. The objectives of this study were to (1) collate a global database of enteric CH
4 production from individual lactating dairy cattle; (2) determine the availability of key variables for predicting enteric CH
4 production (g/day per cow), yield [g/kg dry matter intake (DMI)], and intensity (g/kg energy corrected milk) and their respective relationships; (3) develop intercontinental and regional models and cross‐validate their performance; and (4) assess the trade‐off between availability of on‐farm inputs and CH
4 prediction accuracy. The intercontinental database covered Europe (EU), the United States (US), and Australia (AU). A sequential approach was taken by incrementally adding key variables to develop models with increasing complexity. Methane emissions were predicted by fitting linear mixed models. Within model categories, an intercontinental model with the most available independent variables performed best with root mean square prediction error (RMSPE) as a percentage of mean observed value of 16.6%, 14.7%, and 19.8% for intercontinental, EU, and United States regions, respectively. Less complex models requiring only DMI had predictive ability comparable to complex models. Enteric CH
4 production, yield, and intensity prediction models developed on an intercontinental basis had similar performance across regions, however, intercepts and slopes were different with implications for prediction. Revised CH
4 emission conversion factors for specific regions are required to improve CH
4 production estimates in national inventories. In conclusion, information on DMI is required for good prediction, and other factors such as dietary neutral detergent fiber (NDF) concentration, improve the prediction. For enteric CH
4 yield and intensity prediction, information on milk yield and composition is required for better estimation.
Common buckwheat is a health-care crop, and continuous cropping is one of the main factors restricting its high-yielding. In order to clarify the mechanism of continuous cropping of buckwheat, 4, 5and 6 years continuous cropping treatments were set up. We obtained the following results. The available nutrients content in rhizosphere soil, soil enzyme activity, leaf area, chlorophyll and soluble protein content, the peroxidase(POD) activity of leaves, agronomic traits, root index (except average diameter) of Fengtian1(FT1) decreased significantly with the increase of continuous cropping years. While, soil pH and the number of fungi in rhizosphere soil increased significantly, the number of bacteria in rhizosphere soil and the activity of catalase (CAT) and superoxide dismutase(SOD) in leaves first increased and then decreased. The yields of continuous cropping for 6 years were 12 times lower than the control crop. In conclusion, continuous cropping has certain effects on growth and yields of buckwheat.
Ruminant livestock enteric fermentation contributes approximately one-third of the global anthropogenic methane (CH4) emissions and is projected to increase significantly to meet the increasing demand for animal-sourced protein. Methane, a short-lived greenhouse gas, needs to be reduced -24 to -47% by 2050 relative to 2010 to meet the 2.0°C target. This study describes the results of a comprehensive meta-analysis to determine effective mitigation strategies. The database included findings from 425 peer-reviewed studies (1963 to 2018). Mitigation strategies were classified into three main categories [animal and feed management, diet formulation, and rumen manipulation (additives and methods used to modify the rumen)] and up to five subcategories (98 total mitigation strategy combinations). A random-effects meta-analysis weighted by inverse variance was carried out (Comprehensive Meta-Analysis, V3.3.070). Five feeding strategies, namely CH4 inhibitors, oils and fats, oilseeds, electron sinks, and tanniferous forages, decreased absolute CH4 emissions by on average -21% (range -12 to -35%) and CH4 emissions per unit of product (CH4I; meat or milk) by on average -17% (range -12 to -32%) without negatively affecting animal production (weight gain or milk yield). Furthermore, three strategies, namely decreasing dietary forage-to-concentrate ratio, increasing feeding level, and decreasing grass maturity, decreased CH4I by on average -12% (range -9 to -17%) and increased animal production by on average 45% (range 9 to 162%). The latter strategies are central to meeting the increasing demand for animal-sourced food. All strategies, but CH4 inhibitors, can be implemented now and offer immediate approaches for combating global warming.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.