The demand for animal protein is expected to rise by 70-80% between 2012 and 2050, while the current animal production sector already causes major environmental degradation. Edible insects are ...suggested as a more sustainable source of animal protein. However, few experimental data regarding environmental impact of insect production are available. Therefore, a lifecycle assessment for mealworm production was conducted, in which greenhouse gas production, energy use and land use were quantified and compared to conventional sources of animal protein. Production of one kg of edible protein from milk, chicken, pork or beef result in higher greenhouse gas emissions, require similar amounts of energy and require much more land. This study demonstrates that mealworms should be considered a more sustainable source of edible protein.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The need for more sustainable production and consumption of animal source food (ASF) is central to the achievement of the sustainable development goals: within this context, wise use of land is a ...core challenge and concern. A key question in feeding the future world is: how much ASF should we eat? We demonstrate that livestock raised under the circular economy concept could provide a significant, nonnegligible part (9–23 g/per capita) of our daily protein needs (~50–60 g/per capita). This livestock then would not consume human‐edible biomass, such as grains, but mainly convert leftovers from arable land and grass resources into valuable food, implying that production of livestock feed is largely decoupled from arable land. The availability of these biomass streams for livestock then determines the boundaries for livestock production and consumption. Under this concept, the competition for land for feed or food would be minimized and compared to no ASF, including some ASF in the human diet could free up about one quarter of global arable land. Our results also demonstrate that restricted growth in consumption of ASF in Africa and Asia would be feasible under these boundary conditions, while reductions in the rest of the world would be necessary to meet land use sustainability criteria. Managing this expansion and contraction of future consumption of ASF is essential for achieving sustainable nutrition security.
The need for more sustainable production and consumption of animal source food (ASF) is central to the achievement of the sustainable development goals: within this context, wise use of land is a core concern. We demonstrate that livestock reared solely on biomass unsuited to human consumption could provide up‐to a third of our daily protein needs. Furthermore, we demonstrate that ASF consumption in Africa and Asia is within the planet's land boundary, while reductions in the rest of the world are needed. Managing this expansion and contraction of future ASF consumption, therefore, is an essential component of achieving sustainable nutrition security.
PURPOSE: Livestock already use most global agricultural land, whereas the demand for animal-source food (ASF) is expected to increase. To address the contribution of livestock to global food supply, ...we need a measure for land use efficiency of livestock systems. METHODS: Existing measures capture different aspects of the debate about land use efficiency of livestock systems, such as plant productivity and the efficiency of converting feed, especially human-inedible feed, into animal products. So far, the suitability of land for cultivation of food crops has not been accounted for. Our land use ratio (LUR) includes all above-mentioned aspects and yields a realistic insight into land use efficiency of livestock systems. LUR is defined as the maximum amount of human-digestible protein (HDP) derived from food crops on all land used to cultivate feed required to produce 1Â kg ASF over the amount of HDP in that 1Â kg ASF. We illustrated our concept for three case systems. RESULTS AND DISCUSSION: The LUR for the case of laying hens equaled 2.08, implying that land required to produce 1Â kg HDP from laying hens could directly yield 2.08Â kg HDP from human food crops. For dairy cows, the LUR was 2.10 when kept on sandy soils and 0.67 when kept on peat soils. The LUR for dairy cows on peat soils was lower compared to cows on sandy soils because land used to grow grass and grass silage for cows on peats was unsuitable for direct production of food crops. A LUR <1.0 is considered efficient in terms of global food supply and implies that animals produce more HDP per square metre than crops. CONCLUSIONS: Values <1.0 demonstrate that livestock produce HDP more efficiently than crops. Such livestock systems (with a LURâ
For design of healthy and sustainable diets and food systems, it is important to consider not only the quantity but also the quality of nutrients. This is particularly important for proteins, given ...the large variability in amino acid composition and digestibility between dietary proteins. This article reviews measurements and metrics in relation to protein quality, but also their application. Protein quality methods based on concentrations and digestibility of individual amino acids are preferred, because they do not only allow ranking of proteins, but also assessment of complementarity of protein sources, although this should be considered only at a meal level and not a diet level. Measurements based on ileal digestibility are preferred over those on faecal digestibility to overcome the risk of overestimation of protein quality. Integration of protein quality on a dietary level should also be done based on measurements on an individual amino acid basis. Effects of processing, which is applied to all foods, should be considered as it can also affect protein quality through effects on digestibility and amino acid modification. Overall, protein quality data are crucial for integration into healthy and sustainable diets, but care is needed in data selection, interpretation and integration.
PURPOSE: The expected increase in demand for food raises concerns about the expansion of agricultural land worldwide. To avoid expansion, we need to focus on increasing land productivity, reducing ...waste, and shifting human diets. Studies exploring diet shifts so far have ignored competition for land between humans and animals. Our objective was to study the relation between land use, the share of animal protein in the human diet, population size, and land availability and quality. METHODS: We used linear programming to determine minimum land required to feed a population a diet with 0â80Â % of the protein derived from terrestrial domestic animals. Populations ranged from 15 million to the maximum number of people that could be supported by the system. The agricultural system in the Netherlands was used as illustration, assuming no import and export of feed and food. Daily energy and protein requirements of humans were fulfilled by a diet potentially consisting of grain (wheat), root and tuber crops (potato, sugar beet), oil crops (rapeseed), legumes (brown bean), and animal protein from ruminants (milk and meat) and monogastrics (pork). RESULTS AND DISCUSSION: Land is used most efficiently if people would derive 12Â % of dietary protein from animals (% PA), especially milk. The role of animals in such a diet is to convert co-products from crop production and the human food industry into protein-rich milk and meat. Below 12Â % PA, human-inedible products were wasted (i.e., not used for food production), whereas above 12Â % PA, additional crops had to be cultivated to feed livestock. Large populations (40 million or more) could be sustained only if animal protein was consumed. This results from the fact that at high population sizes, land unsuitable for crop production was necessary to meet dietary requirements of the population, and contributed to food production by providing animal protein without competing for land with crops. CONCLUSIONS: A land use optimization model including crop and animal production enables identification of the optimal % PA in the diet. Land use per capita was lowest at 12Â % PA. At this level, animals optimally consume co-products from food production. Larger populations, furthermore, can be sustained only with diets relatively high in % PA, as land unsuitable for crop production is needed to fulfil their food demand. The optimal % PA in the human diet depended on population size and the relative share of land unsuitable for crop production.
Purpose
Input parameters required to quantify environmental impact in life cycle assessment (LCA) can be uncertain due to e.g. temporal variability or unknowns about the true value of emission ...factors. Uncertainty of environmental impact can be analysed by means of a global sensitivity analysis to gain more insight into output variance. This study aimed to (1) give insight into and (2) compare methods for global sensitivity analysis in life cycle assessment, with a focus on the inventory stage.
Methods
Five methods that quantify the contribution to output variance were evaluated: squared standardized regression coefficient, squared Spearman correlation coefficient, key issue analysis, Sobol’ indices and random balance design. To be able to compare the performance of global sensitivity methods, two case studies were constructed: one small hypothetical case study describing electricity production that is sensitive to a small change in the input parameters and a large case study describing a production system of a northeast Atlantic fishery. Input parameters with relative small and large input uncertainties were constructed. The comparison of the sensitivity methods was based on four aspects: (I) sampling design, (II) output variance, (III) explained variance and (IV) contribution to output variance of individual input parameters.
Results and discussion
The evaluation of the sampling design (I) relates to the computational effort of a sensitivity method. Key issue analysis does not make use of sampling and was fastest, whereas the Sobol’ method had to generate two sampling matrices and, therefore, was slowest. The total output variance (II) resulted in approximately the same output variance for each method, except for key issue analysis, which underestimated the variance especially for high input uncertainties. The explained variance (III) and contribution to variance (IV) for small input uncertainties were optimally quantified by the squared standardized regression coefficients and the main Sobol’ index. For large input uncertainties, Spearman correlation coefficients and the Sobol’ indices performed best. The comparison, however, was based on two case studies only.
Conclusions
Most methods for global sensitivity analysis performed equally well, especially for relatively small input uncertainties. When restricted to the assumptions that quantification of environmental impact in LCAs behaves linearly, squared standardized regression coefficients, squared Spearman correlation coefficients, Sobol’ indices or key issue analysis can be used for global sensitivity analysis. The choice for one of the methods depends on the available data, the magnitude of the uncertainties of data and the aim of the study.
Abstract
Carbon sequestration in grasslands has been proposed as an important means to offset greenhouse gas emissions from ruminant systems. To understand the potential and limitations of this ...strategy, we need to acknowledge that soil carbon sequestration is a time-limited benefit, and there are intrinsic differences between short- and long-lived greenhouse gases. Here, our analysis shows that one tonne of carbon sequestrated can offset radiative forcing of a continuous emission of 0.99 kg methane or 0.1 kg nitrous oxide per year over 100 years. About 135 gigatonnes of carbon is required to offset the continuous methane and nitrous oxide emissions from ruminant sector worldwide, nearly twice the current global carbon stock in managed grasslands. For various regions, grassland carbon stocks would need to increase by approximately 25% − 2,000%, indicating that solely relying on carbon sequestration in grasslands to offset warming effect of emissions from current ruminant systems is not feasible.
•Sustainability assessment tools aim to support sustainable development of farms.•Limited attention is paid to comparing tools in farming practice.•Tools vary widely in scoring methods, ...context-specificity and assumptions.•Assessment results are a starting point for discussion, reflection and learning.
In the past decades a wide variety of tools have been developed to assess the sustainability performance of farms. Although multiple studies have compared tools on a theoretical basis, little attention has been paid to the comparing tools in practice. This research compared indicator-based sustainability assessment tools to gain insight in practical requirements, procedures and complexity involved in applying sustainability assessment tools. In addition, the relevance of the tools, as perceived by farmers, was evaluated. An overview of 48 indicator-based sustainability assessment tools was developed to, subsequently, select tools that address the environmental, social and economic dimension of sustainability, are issued in a scientific publication and suitable for assessing the sustainability performance of livestock and arable farms in Denmark. Only four tools (RISE, SAFA, PG and IDEA) complied with the selection criteria and were used to assess the sustainability performance of five Danish farms. The tools vary widely in their scoring and aggregation method, time requirement and data input. The farmers perceived RISE as the most relevant tool to gain insight in the sustainability performance of their farm. The findings emphasize the importance of context specificity, user-friendliness, complexity of the tool, language use, and a match between value judgements of tool developers and farmers. Even though RISE was considered as the most relevant tool, the farmers expressed a hesitation to apply the outcomes of the four tools in their decision making and management. Furthermore, they identified limitations in their options to improve their sustainability performance. Additional efforts are needed to support farmers in using the outcomes in their decision making. The outcomes of sustainability assessment tools should therefore be considered as a starting point for discussion, reflection and learning.
The assessment of the performance of nutrient use along livestock supply chains can help to identify targeted nutrient management interventions, with a goal to benchmark and to monitor the ...improvement of production practices. It is necessary, therefore, to develop indicators that are capable to describe all nutrient dynamics and management along the chain. This paper proposed a comprehensive framework, based on life-cycle thinking, to assess the sustainability of nitrogen and phosphorus use. The proposed framework represents nutrient flows in typical livestock supply chain from the “cradle-to-primary-processing-gate”, including crop/pasture production, animal production, and primary processing stage as well as the transportation of feed materials, live-animals or animal products. In addition, three indicators, including the life-cycle nutrient use efficiency (life-cycle-NUE), life-cycle net nutrient balance (life-cycle-NNB) and nutrient hotspot index (NHI) were proposed and tested in a case study of mixed dairy supply chains in Europe. Proposed indicators were found to be suitable to describe different aspects of nitrogen and phosphorus dynamics and, therefore, were all needed. Moreover, the disaggregation of life-cycle-NUE and life-cycle-NNB has been investigated and the uncertainties related to the choice of the method used to estimate changes in nutrient soil stock have been discussed. Given these uncertainties, the choice of method to compute the proposed indicators is determined by data availability and by the goal and scope of the exercise.
•We test a framework to assess the performance of nutrient use in livestock systems.•The framework accounts for more nutrient processes, pools and end-uses.•We propose three indicators required to describe nutrient dynamics and performance.•The framework is sensitive to methods selected to estimate nutrient stock change.
Objective: This study was conducted to provide models to accurately predict nitrogen (N) and phosphorus (P) excretion of dairy cows on smallholder farms in Indonesia based on readily available farm ...data.Methods: The generic model in this study is based on the principles of the Lucas equation, describing the relation between dry matter intake (DMI) and faecal N excretion to predict the quantity of faecal N (QFN). Excretion of urinary N and faecal P were calculated based on National Research Council recommendations for dairy cows. A farm survey was conducted to collect input parameters for the models. The data set was used to calibrate the model to predict QFN for the specific case. The model was validated by comparing the predicted quantity of faecal N with the actual quantity of faecal N (QFNACT) based on measurements, and the calibrated model was compared to the Lucas equation. The models were used to predict N and P excretion of all 144 dairy cows in the data set.Results: Our estimate of true N digestibility equalled the standard value of 92% in the original Lucas equation, whereas our estimate of metabolic faecal N was –0.60 g/100 g DMI, with the standard value being –0.61 g/100 g DMI. Results of the model validation showed that the R2 was 0.63, the MAE was 15 g/animal/d (17% from QFNACT), and the RMSE was 20 g/animal/d (22% from QFNACT). We predicted that the total N excretion of dairy cows in Indonesia was on average 197 g/animal/d, whereas P excretion was on average 56 g/animal/d.Conclusion: The proposed models can be used with reasonable accuracy to predict N and P excretion of dairy cattle on smallholder farms in Indonesia, which can contribute to improving manure management and reduce environmental issues related to nutrient losses.
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