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A greenhouse gas emissions analysis (carbon footprint) was conducted for cultivation, harvesting, and production of common dairy feeds used for the production of dairy milk in the USA. The goal was to determine the carbon footprint (grams CO2 equivalents (gCO2e)/kg of dry feed) in the USA on a regional basis, identify key inputs, and make r...
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... rates for N reported in California; approximately three times the rates applied in other areas. This is partially offset by larger yields; however, the yield is only 1.5 to 1.7 times that of other regions. Grass has a higher carbon footprint than other forage crops and nearly as high as corn grain. Regional results for each feed analyzed were combined to estimate the national carbon footprint (see Table 6). Overall, processed coproducts like wet mill and dry mill DDGS and soybean meal show higher GHG emissions. Results in Table 6 can be compared to recent literature values, though some of these studies occurred in different geographic contexts. Landis et al. (2007) modeled the agro- system material flows for US corn and soybean by employ- ing the greenhouse gases, regulated emissions, and energy use in transportation (GREET) model. The following results were obtained by Landis et al. (2007): 310 – 680 gCO 2 e/kg of dry corn and 120 – 290 gCO 2 e/kg of dry soybean. The carbon footprint results for corn and soybean at the farm stage from GREET (2010) were 290 and 200 gCO 2 e/kg of dry crop, respectively. Two separate studies by Kim and Dale (2009a — 40 counties in the USA) and Kim et al. (2009b — eight counties in the USA) estimated 360±100 and 540±290 gCO 2 e/kg of dry corn grain, respectively, for US corn-producing counties. In our study, the national carbon footprint of corn grain was estimated to be 390 gCO 2 e/ kg of dry corn grain, with upper and lower bounds of 270 and 560 gCO 2 e/kg of dry corn grain. Additionally, a value of 300 gCO 2 e was estimated for 1 kg dry corn at field using the United States Life Cycle Inventory database in SimaPro (PRé Consultants 2009). The GHG emissions of 1 kg corn silage at the farm gate for the Swiss production processes using Ecoinvent Database was 190 gCO 2 e/kg of dry corn silage, a value close to corn silage for our study in Table 6. A value of 620 gCO 2 e/kg dry soybean was obtained from the Denmark LCA food database in SimaPro (Denmark LCA Food 2011 and PRé Consultants 2009). Dalgaard et al. (2008), using the EDIP 97 database (a Danish LCA methodology) in SimaPro (PRé Consultants 2009), analyzed the GWP of 1 kg (dry) of soybean meal to be 721gCO 2 e while Pelletier (2008) in the study of the environmental performance in the US broiler poultry sector estimated 297 gCO 2 e. Finally, another European study by Van der Werf et al. (2005) estimated the GHG emissions for the production of 1 kg of wheat and barley to be 375 and 400 gCO 2 e/kg of dry crop, respectively, while the Denmark LCA food database (PRé Consultants 2009) estimates 710 and 570 gCO 2 e for 1 kg of dry wheat and oats, respectively. Taking into account the differences in modeling tools, study scope, and geographical context for the different studies, results from the literature are generally com- parable to those obtained in this study. The following sections will display the results in more detail with regard to the relative importance of specific crop life cycle stages and inputs. Soybean showed a lower carbon footprint than some crops due to lower inorganic nitrogen fertilizer application, and this was largely due to the fact that it is a nitrogen-fixing crop. However, significant contributors to the various regional results are: lime application, gasoline, diesel, and N 2 O emissions from soybean residues, as shown in Fig. 3. Together, they contributed about 70 – 86% of the overall GHG emissions in each productive dairy region. Interesting was the relative impact of lime input on the overall regional footprints. Lime input data for regions 2 and 3 for the soybean-producing states were relatively comprehensive (60% and 100% of states reporting, respectively). For region 4, data for lime application were available for just two states out of the six soybean-producing states. Another probable reason could have been the acidic nature of soils in regions 2 and 3 requiring more lime to increase soil pH for plant growth. Emissions of N 2 O from crop residues were large compared to N 2 O released from the application of N fertilizers for soybeans, a distinctly different feature compared to other crops. Approximately 65% of GHG emissions from N fertilizers were due to field application, with about 35% from manufacture, as also seen from the data in Table 5. Although it was not exactly clear why the states in the midwest (region 3) used relatively lower amounts of diesel, one possible reason was the effect of the Midwest Clean Initiative Diesel (EPA 2011) which encourages operational changes, technological improvements, and use of cleaner fuels for powering equipment. Finally, using the pedigree matrix, the standard deviation with 95% confidence interval for inorganic fertilizer, crop protection chemicals, and energy inputs was estimated to be 1.51, 1.21, and 1.57, respectively (see Appendix G-11 of the Electronic Supplementary Material). The major contributors to the oats carbon footprint in the USA (Fig. 4) were identified to be inorganic nitrogen and phosphate fertilizers, manure, lime application, diesel, and the impact of N 2 O emissions from oat residues, which together makes up approximately 72 – 92% of the overall footprint in each region. The regional variation in carbon footprint was due to the impact of fertilizer application rate. For example, dairy region 5 shows an unusually high carbon footprint of 1,100 gCO 2 e/kg of oats harvested, due to high fertilizer N application. Furthermore, results from California in region 5 may not be representative of the other states in this region. About 65% of inorganic N fertilizer GHG emissions was from field application and 35% was due to manufacture. The impact of crop residues remains fairly constant across the various regions for oats, contributing about 9% on national average towards the carbon footprints reported. However, the use of manure to supplement inorganic fertilizers in regions 1 and 3 contributed 21% and 26%, respectively, towards the regional footprints. Finally, in the case of oats, the standard deviation with 95% confidence for inorganic fertilizer, chemical protection, and energy inputs was estimated to be 1.51, 1.24, and 1.36, respectively (see Appendix G-11 of the Electronic Supplementary Material). Inorganic fertilizers, manure, phosphates, lime, diesel as well as the impacts of grain drying and N 2 O emissions due to residues contributed approximately 80 – 90% towards the regional C footprint of corn grain (Fig. 5). In the corn silage analysis in Fig. 6, inorganic fertilizers, manure, phosphates, lime, diesel as well as the impacts of drying and N 2 O emissions due to residues contributed about 73 – 90% towards the corn silage footprint for each dairy region. The contribution of the MMS to the GHG emissions for both crops was small (always <2%). Generally, the GHG emissions for corn grain with respect to the various dairy regions were about two times greater than for the corn silage. The comparatively larger emissions for corn grain compared to silage were mainly due to the allocation method applied from Section 3.1, under “ Corn ” . Figure 5 shows high contributions of inorganic fertilizer from region 2, as this is the reason why additional manure was not added to supplement plant growth in this region. Interestingly, Fig. 6 shows a relatively high contribution for the use of natural gas for region 4 and this was primarily due to extremely high level of energy requirements from corn farms in Texas. In the final analysis, the standard deviation with 95% confidence for fertilizer, chemical protection, and energy inputs was estimated to be 1.51, 1.21, and 1.26, respectively, (see Appendix G-11 of the Electronic Supplementary Material) using the pedigree matrix. Regions 3 and 4 showed the highest carbon footprint (Fig. 7), largely due to the high rate of application of inorganic nitrogen fertilizers by farmers. Inorganic nitrogen and phosphate fertilizers, diesel, and the impact of N 2 O releases contributed 93 – 95% of the overall GHG emissions in each dairy region. As in other crops, about 65% of inorganic N fertilizer GHG emissions was from field application and 35% was due to fertilizer manufacture. On the whole, the carbon footprints for all dairy feed crops analyzed in this study were within the range 160 – 1140 gCO 2 e/kg of dry feed. Various contributions of different farm inputs varied on a regional basis and this was mainly due to the different fertilizer, liming, and energy requirements depending on location, soil properties, and climate. The major contributors towards the regional footprints for both alfalfa hay and silage were identified to be due to crop residue, phosphate, lime, diesel, and electricity. In all regions, these factors contributed between 80% and 90% toward the overall regional footprint. However, impacts due to the application of potash, boron, crop protection chemicals, and use of gasoline were minimal ranging between 4% and 14% toward the carbon footprint for both alfalfa hay and silage. Contributions to carbon (GHG) footprint due to the application of inorganic fertilizer for both alfalfa hay and silage was less than 10% in all dairy production regions for which input data were available, and this low result was not surprising given that alfalfa is a nitrogen-fixing crop. Grass showed a higher carbon footprint than other forage crops and nearly as high as the corn grain. Grass typically requires less maintenance and inputs, but produces lower yields than many other crops. In addition, there is much higher variability and uncertainty in actual yield than for other commodity crops. Region 2, which has the highest carbon footprint for grass and hay production, also had higher fuel, lime, and nitrogen use based on the available budget information. In all the different types of grass analyzed, inorganic fertilizers were the major contributors ranging from 34% to as high as 90% toward the footprint in ...
Citations
... Ultimately, the difference between digestible and resistant starch plays an important role in the microbial composition in the hindgut [59], the pig body composition, and subsequent growth [57]. It also plays an important role in the carbon footprint of feed production, as drying consumes more energy than ensiling [60]. ...
The aim of the present study was to determine the in vitro starch digestibility kinetics of rehydrated maize grain silages in pigs and to investigate the relationship between the in vitro starch digestibility rate and the physical properties of the mature grain. Grains of seven commercial maize hybrids were harvested at physiological maturity, rehydrated, and ensiled with a commercial inoculant during different ensiling periods (0, 21, and 95 days) in five replicates using a completely randomized design. The starch digestibility rate was determined using first-order kinetics following an in vitro digestibility procedure mimicking the stomach and small intestine of pigs. The tested hybrids differed in their physical properties (test weight, kernel size, and density and hardness), digestion coefficients, and starch digestibility rate (p < 0.05). The starch digestibility rate increased with an increasing ensiling period, with average values of 0.588, 1.013, and 1.179 1/h for 0, 21, and 95 days of ensiling period, respectively. However, the effect of ensiling was more pronounced in hybrids with higher grain hardness, reaching a rate of 1.272 1/h in hybrids with higher grain hardness compared to 1.110 1/h in hybrids with lower grain hardness. In conclusion, ensiling results in higher availability of starch to digestive enzymes, and the duration of ensiling and hardness of the maize hybrid should be considered when formulating the pig diet.
... In terms of grain production, the GWPs of grain maize and silage maize were estimated to be 1.67 kg CO 2 eq/kg DM and 0.29 kg CO 2 eq/kg DM, respectively. The GWP of silage maize in our study closely aligns with that reported in previous studies conducted in the United States, Denmark, and China, which noted findings ranging between 0.2 and 0.24 (Adom et al., 2012;Liu et al., 2017). Our GWP results for maize were higher than those in prevailing assessments, which ranged from 0.37 to 1.21 kg CO 2 eq Wang et al., 2016;Yan et al., 2015). ...
Significant efforts are underway in developing countries to shift cropping systems with the purpose of alleviating forage supply–demand conflicts. However, few studies have comprehensively evaluated cropping system adaptation strategies at a regional scale. This study established a systematic framework for designing and performing integrated assessments of cropping system transitions, incorporating analyses of forage supply–demand balance and multiperspective performance evaluations. Through a case study in Chengde, China, the results revealed a significant forage supply–demand imbalance in 2020. Forage production could support only approximately 31% of the region's livestock population, resulting in a deficit of 5.18 billion kg. Addressing this forage deficit requires shifting 12,299.62 ha from grain maize cultivation to silage maize cultivation. An economic analysis indicated that this shift could increase total profit by 15.74 for Chengde's farmers. With respect to the environment, a life cycle assessment revealed a 53.63% reduction in global warming potential, equivalent to 5.03 × 10⁴ t CO2 eq. These results highlight that shifting cropping systems can effectively address forage deficits while achieving economic profitability and environmental sustainability. Our study suggests that the transition of cropping systems in agropastoral regions facing similar challenges to achieve sustainable agro-pastoral development should be encouraged.
Graphical abstract
... [9][10][11] but is not detailed here. In agriculture, Adom et al. (2012) reported greenhouse gas emissions from common dairy feeds in the United States (US) [12]. In public health, Okeke (2022) examined the impact of human carbon footprints, with an emphasis on Africa [13]. ...
... [9][10][11] but is not detailed here. In agriculture, Adom et al. (2012) reported greenhouse gas emissions from common dairy feeds in the United States (US) [12]. In public health, Okeke (2022) examined the impact of human carbon footprints, with an emphasis on Africa [13]. ...
Turbulent flow physics regulates the aerodynamic properties of lifting surfaces, the thermodynamic efficiency of vapor power systems, and exchanges of natural and anthropogenic quantities between the atmosphere and ocean, to name just a few applications. The dynamics of turbulent flows are described via numerical integration of the non-linear Navier-Stokes equation -- a procedure known as computational fluid dynamics (CFD). At the dawn of scientific computing in the late 1950s, it would be many decades before terms such as ``carbon footprint'' or ``sustainability'' entered the lexicon, and longer still before these themes attained national priority throughout advanced economies. This paper introduces a framework designed to calculate the carbon footprint of CFD and its contribution to carbon emission reduction strategies. We will distinguish between "hero" and "routine" calculations, noting that the carbon footprint of hero calculations is largely determined by the energy source mix utilized. We will also review CFD of flows where turbulence effects are modeled, thus reducing the degrees of freedom. Estimates of the carbon footprint are presented for such fully- and partially-resolved simulations as functions of turbulence activity and calculation year, demonstrating a reduction in carbon emissions by two to five orders of magnitude at practical conditions. Beyond analyzing CO2 emissions, we quantify the benefits of applying CFD towards overall carbon emission reduction. The community's effort to avoid redundant calculations via turbulence databases merits particular attention, with estimates indicating that a single database could potentially reduce CO2 emissions by approximately O(1) million metric tons. Additionally, implementing CFD in the fluids industry has markedly decreased dependence on wind tunnel testing, which is anticipated to lead to CO2 emission reduction.
... Charles, et al. 2005 No Region Listed Good agricultural practices used, based on Swiss regulations. Pathak, et al. 2010 India Conventional preparation practices Pathak, et al. 2010 India Conventional processing practices Pathak, et al. 2010India Conventional producing practice Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product Adom, et al. 2012 NE USA Conventional USA growing practices Adom, et al. 2012 S USA Conventional USA growing practices Adom, et al. 2012 Midwest USA Conventional USA growing practices Adom, et al. 2012 Rockies USA Conventional USA growing practices Noya, et al. 2015 Italy Conventional growing practices Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product/ Per kg of crushed grain Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product/ Per kg of flour Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product Adom, et al. 2012 NE USA Conventional USA growing practices Adom, et al. 2012 Midwest USA Conventional USA growing practices Adom, et al. 2012 Rockies USA Conventional USA growing practices Adom, et al. 2012 Pacific Coast Conventional USA growing practices Gonzá lez- Garcí a, et al. 2016 USA Fertilized with 170 kg of cattle slurry/ ha Gonzá lez- Garcí a, et al. 2016Finland Conventional production practices Hess, et al. 2014 Italy Produced in integrated process plants having an average productivity of 1,000 tons of pasta/day. Cancino-Espinoza, et al. 2018 Peru/ Bolivia Conventional production practices for a 500 g packet of quinoa Pathak, et al. 2010India Conventional Growing Practices Pathak, et al. 2010 India Total emission of CO2 was calculated from the amount of diesel used for transport and processing, and liquid petroleum gas (LPG) for preparation of food. ...
... Charles, et al. 2005 No Region Listed Good agricultural practices used, based on Swiss regulations. Pathak, et al. 2010 India Conventional preparation practices Pathak, et al. 2010 India Conventional processing practices Pathak, et al. 2010India Conventional producing practice Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product Adom, et al. 2012 NE USA Conventional USA growing practices Adom, et al. 2012 S USA Conventional USA growing practices Adom, et al. 2012 Midwest USA Conventional USA growing practices Adom, et al. 2012 Rockies USA Conventional USA growing practices Noya, et al. 2015 Italy Conventional growing practices Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product/ Per kg of crushed grain Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product/ Per kg of flour Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product Adom, et al. 2012 NE USA Conventional USA growing practices Adom, et al. 2012 Midwest USA Conventional USA growing practices Adom, et al. 2012 Rockies USA Conventional USA growing practices Adom, et al. 2012 Pacific Coast Conventional USA growing practices Gonzá lez- Garcí a, et al. 2016 USA Fertilized with 170 kg of cattle slurry/ ha Gonzá lez- Garcí a, et al. 2016Finland Conventional production practices Hess, et al. 2014 Italy Produced in integrated process plants having an average productivity of 1,000 tons of pasta/day. Cancino-Espinoza, et al. 2018 Peru/ Bolivia Conventional production practices for a 500 g packet of quinoa Pathak, et al. 2010India Conventional Growing Practices Pathak, et al. 2010 India Total emission of CO2 was calculated from the amount of diesel used for transport and processing, and liquid petroleum gas (LPG) for preparation of food. ...
... Charles, et al. 2005 No Region Listed Good agricultural practices used, based on Swiss regulations. Pathak, et al. 2010 India Conventional preparation practices Pathak, et al. 2010 India Conventional processing practices Pathak, et al. 2010India Conventional producing practice Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product Adom, et al. 2012 NE USA Conventional USA growing practices Adom, et al. 2012 S USA Conventional USA growing practices Adom, et al. 2012 Midwest USA Conventional USA growing practices Adom, et al. 2012 Rockies USA Conventional USA growing practices Noya, et al. 2015 Italy Conventional growing practices Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product/ Per kg of crushed grain Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product/ Per kg of flour Xu, et al. 2017 China Medium-scale mill and crusher were used to produce product Adom, et al. 2012 NE USA Conventional USA growing practices Adom, et al. 2012 Midwest USA Conventional USA growing practices Adom, et al. 2012 Rockies USA Conventional USA growing practices Adom, et al. 2012 Pacific Coast Conventional USA growing practices Gonzá lez- Garcí a, et al. 2016 USA Fertilized with 170 kg of cattle slurry/ ha Gonzá lez- Garcí a, et al. 2016Finland Conventional production practices Hess, et al. 2014 Italy Produced in integrated process plants having an average productivity of 1,000 tons of pasta/day. Cancino-Espinoza, et al. 2018 Peru/ Bolivia Conventional production practices for a 500 g packet of quinoa Pathak, et al. 2010India Conventional Growing Practices Pathak, et al. 2010 India Total emission of CO2 was calculated from the amount of diesel used for transport and processing, and liquid petroleum gas (LPG) for preparation of food. ...
The global reliance upon cereal grains, not only for domestic consumption, but also for export in international markets continues to be critical to many countries’ economies. The ecological impacts of the various steps along the supply chain required to get product to the consumer, whether it be fuel, feed, or food, have significant environmental impacts. Ecological assessments have focused historically upon carbon footprints, but by considering other measures of life cycle assessments (LCA), we can come to a better understanding of the environmental significance that some of the most critical crops in our world have. The goal of this study was to compile environmental impact data from published literature and conduct synthesis to determine ecological trends. Published data was compiled and analyzed to determine where critical environmental shortcomings were in the cereal grain industry. Analysis of these data will enable recommendations to be made concerning the weaker spots in supply chains (i.e., more environmentally impactful). In addition, by expanding the geographic locations to an international scale, this study will allow for environmental impacts to be assessed based on various approaches found across the globe. As long as our world continues to place significant emphasis on cereal grains as foundations for societies, we need to better understand the ramifications of these critical crops' ecological impacts and how best to address them.
... The remaining model inputs were feedlot-and pen-level data from the trial. Impacts of feed were included based on the production of individual ingredients and associated CO 2 , N 2 O, and CH 4 emissions from cultivation, planting, fertilization, pesticide use, and harvesting using published carbon footprint values for feed ingredients [37,38]. Individual dietary components for each formulation (Table 1) and the total dry feed delivered of each (to pens) were part of this estimate. ...
Simple Summary
Bovine respiratory disease (BRD) is the most impactful health disorder in the cattle industry. Metaphylaxis, administration of an antimicrobial to a group of animals at risk for BRD, is a proven method for reducing morbidity and mortality in at-risk populations. However, judicious antimicrobial use is warranted. Medium-risk cattle are a lesser studied population (versus high-risk), where advantages and disadvantages of metaphylaxis are less known, and thus there is more uncertainty on whether or not it should be used. Our objectives were to evaluate the effects of metaphylaxis in a medium-risk population on a comprehensive set of outcomes of value to stakeholders, to estimate the costs and benefits of using or not using metaphylaxis. Using a pull-and-treat program in lieu of metaphylaxis for BRD resulted in substantially less antimicrobial use. However, metaphylaxis improved animal health, performance, and estimated greenhouse gas emissions. While antimicrobial metaphylaxis could be removed from medium-risk populations, there are likely costs associated with such an action that would have negative impacts on animal wellbeing, beef production, economics, and emissions. The framework of values discussed herein should be fully considered by stakeholders considering antimicrobial use decisions.
Abstract
The objectives were to evaluate the effects of metaphylaxis (META) and pull-and-treat (PT) programs on health, antimicrobial use, beef production, economics, and greenhouse gas emissions in cattle at medium risk for bovine respiratory disease (BRD). A randomized complete block design was used at two US commercial feedlots. Steers and heifers [2366 total; 261 (±11.0) kg initial weight] were blocked by sex and feedlot arrival, and allocated to one of two pens within a block (16 pens total, eight blocks). Pens were randomly assigned to treatment: META, tulathromycin injection at initial processing; or PT, tulathromycin injection only for first clinical BRD treatment. Data were analyzed with linear and generalized linear mixed models. There was greater BRD morbidity in PT than META cattle (17.2% vs. 7.3% respectively; p < 0.01), and greater total mortality (2.5% vs. 1.1% respectively; p = 0.03). Per animal enrolled, 1.1 antimicrobial doses were used for META compared to 0.2 for PT (p < 0.01). Per animal enrolled, final live (p = 0.04) and carcass (p = 0.08) weights were greater for META than PT; however, net returns ($/animal) were not significantly different (p = 0.71). Compared to PT, total lifetime estimated CO2 equivalent emissions from production were reduced by 2% per unit of live weight for META (p = 0.09). While antimicrobial use was reduced with PT, there may be substantial negative impacts on other outcomes if META was not used in this type of cattle population.
... Although the present work is focused solely on emissions from silage fermentation, the outcomes are relevant to broader carbon footprint analysis efforts at the level of animal production and farm operations. Quantitative sustainability and CO 2 e footprint efforts have been advancing for well over a decade in dairy (Del Prado et al., 2011;Adom et al., 2012;Henriksson et al., 2014) and beef production (Rotz et al., 2013). Holistic farm carbon footprint assessments have not been limited to feedstuffs, but have also considered the roles of feeds, nutrients, and additives on enteric methane emissions (Little et al., 2017;Meller et al., 2019;Bannink et al., 2020). ...
... With GWP 20 of 1.9 ± 5.6% of silage dry matter calculated in the present work, corn silage fermentation is projected to account for 791 kt of CO 2 e on a 20 year horizon. On a 100 year horizon (GWP 100 of 0.2 ± 5.5%), CO 2 e emissions total approximately 83 kt, although the 95% confidence interval demonstrates that this value is not significantly different from 0. For additional perspective, the CO 2 e footprint of corn silage production has been estimated at approximately 200 g CO 2 e per kg dry matter, or approximately 20% by mass (Adom et al., 2012). ...
The European Climate Law recently codified the goal for European climate neutrality by 2050, highlighting the need for sustainable farming practices within a robust and transparent carbon dioxide equivalent (CO 2 e) accounting system. In the present study, a series of equations were proposed for the estimation of CO 2 e emissions from corn silage fermentation. Systematic review of previous meta-analyses of corn silage fermentation identified the mean and standard deviation statistics for key model inputs of acetic acid, ethanol, lactic acid, ammonia, and volatile-corrected dry matter loss. Estimates of CO 2 e emissions were determined for a mock dataset comprising 1,000 iterations of randomly-generated values for each metric in accordance with mean and variance statistics of the source data. Estimates for CO 2 e emissions of corn silage based on meta-analysis review of laboratory experiments were 1.9 ± 5.6% (GWP 20 ) and 0.2 ± 5.5% (GWP 100 ) of silage dry matter. Furthermore, model results demonstrated a precedent for CO 2 recycling by silage microorganisms, which was supported by genome annotation of strains belonging to common silage species. Linear model equations for GWP 20 and GWP 100 with inputs and outputs in mg kg ⁻¹ silage dry matter were developed, where inputs are acetic acid (A), ethanol (E), lactic acid (L), and volatile corrected dry matter loss (D V ). Linear equations are (for GWP 20 ; Eq. 11):
GWP 20 = − 3626.1 − 0.04343 A + 0.8011 E − 0.03173 L + 1.46573 D V
and for GWP 100 ; Eq. 12:
GWP 100 = − 8526.10 − 0.22403 A − 0.11963 E − 0.03173 L + 1.46573 D V .
... Further, Liu et al. [60] stated that improving N fertilizer use efficiency can lower the carbon footprints of field crops as N fertilizer contributes 36 to 52% of the total emissions. Even in the USA, the application of both synthetic fertilizers and lime were identified as major contributors to carbon footprint in dairy feeds such as soybeans, alfalfa, corn and others [61]. Thus, GHG emissions can be effectively minimized by optimizing the N application rate, N form and fertilizer application method, and further using biochar, nitrification or urease inhibitors, as well as by adopting measures such as crop mulching, use of organic manures, green manuring crops and irrigation scheduling management [8,62,63]. ...
Efficient use of available resources in agricultural production is important to minimize carbon footprint considering the state of climate change. In this context, the current research was conducted to identify carbon and energy-efficient fodder cropping systems for sustainable livestock production. Annual monocropping, perennial monocropping, annual cereal + legume intercropping and perennial cereal + legume intercropping systems were evaluated by employing a randomized complete block design with three replications under field conditions. The lucerne (Medicago sativa L.) monocropping system recorded significantly lower carbon input (274 kg-CE ha⁻¹ year⁻¹) and showed higher carbon indices viz., carbon sustainability index (165.8), the carbon efficiency ratio (166.8) and carbon efficiency (347.5 kg kg-CE⁻¹) over other systems. However, higher green fodder biomass led to statistically higher carbon output (78,542 kg-CE ha⁻¹ year⁻¹) in the Bajra–Napier hybrid (Pennisetum glaucum × Pennisetum purpureum) + lucerne perennial system. Similar to carbon input, lower input energy requirement (16,106 MJ ha⁻¹ year⁻¹) and nutrient energy ratio (25.7) were estimated with the lucerne perennial system. However, significantly higher energy output (376,345 and 357,011 MJ ha⁻¹ year⁻¹) and energy indices viz., energy use efficiency (13.3 and 12.2), energy productivity (5.8 and 5.3 kg MJ⁻¹), net energy (327,811 and 347,961 MJ ha⁻¹ year⁻¹) and energy use efficiency (12.3 and 11.2) were recorded with Bajra–Napier hybrid + legume [lucerne and cowpea (Vigna unguiculata (L.) Walp.)] cropping systems, respectively. However, these systems were on par with the lucerne monocropping system. Additionally, Bajra–Napier hybrid + legume [cowpea, sesbania (Sesbania grandiflora (L.) Pers.) and lucerne] cropping systems also showed higher human energy profitability. Concerning various inputs’ contribution to total carbon and energy input, chemical fertilizers were identified as the major contributors (73 and 47%), followed by farmyard manure (20 and 22%) used to cultivate crops, respectively, across the cropping systems. Extensive use of indirect (82%) and non-renewable energy sources (69%) was noticed compared to direct (18%) and renewable energy sources (31%). Overall, perennial monocropping and cereal + legume cropping systems performed well in terms of carbon and energy efficiency. However, in green biomass production and carbon and energy efficiency, Bajra–Napier hybrid + legume (lucerne and cowpea) cropping systems were identified as the best systems for climate-smart livestock feed production.
... Most forages are produced on-farm, whereas inclusion of concentrates (grains and by-products) depends on availability in the region (Table 2). Thus, it is important to consider regional emission factors for each feed ingredient, which may vary due to differences in climatic conditions and production systems (Adom et al., 2012). Thus, regional emission factors for each feed ingredient were adopted from recent LCA studies, which determined carbon footprint for each feed in- gredient produced in the regions and accounted for all inputs (e.g., seed, fertilizer, insecticide), outputs, and associated indirect and direct emissions (Adom et al., 2012). ...
... Thus, it is important to consider regional emission factors for each feed ingredient, which may vary due to differences in climatic conditions and production systems (Adom et al., 2012). Thus, regional emission factors for each feed ingredient were adopted from recent LCA studies, which determined carbon footprint for each feed in- gredient produced in the regions and accounted for all inputs (e.g., seed, fertilizer, insecticide), outputs, and associated indirect and direct emissions (Adom et al., 2012). If regional emission factors were not available for any feed ingredients, we determined the emission factors as described by Naranjo et al. (2020) or Uddin et al. (2021), which take into account all the inputs (e.g., seed, fertilizer, insecticide), outputs, and associated emissions (indirect and direct) needed to produce those ingredients (Supplemental Table S4; https: / / doi .org/ 10 .17632/ ...
It is estimated that enteric methane (CH 4) contributes about 70% of all livestock greenhouse gas (GHG) emissions. Several studies indicated that feed additives such as 3-nitrooxypropanol (3-NOP) and nitrate have great potential to reduce enteric emissions. The objective of this study was to determine the net effects of 3-NOP and nitrate on farmgate milk carbon footprint across various regions of the United States and to determine the variability of carbon footprint. A cradle-to-farmgate life cycle assessment was performed to determine regional and national carbon footprint to produce 1 kg of fat-and protein-corrected milk (FPCM). Records from 1,355 farms across 37 states included information on herd structure, milk production and composition, cattle diets, manure management , and farm energy. Enteric CH 4 , manure CH 4 , and nitrous oxide were calculated with either the widely used Intergovernmental Panel on Climate Change Tier 2 or region-specific equations available in the literature. Emissions were allocated between milk and meat using a biophysical allocation method. Impacts of nitrate and 3-NOP on baseline regional and national carbon footprint were accounted for using equations adjusted for dry matter intake and neutral detergent fiber. Uncertainty analysis of carbon footprint was performed using Monte Carlo simulations to capture variability due to inputs data. Overall, the milk carbon footprint for the baseline, nitrate, and 3-NOP scenarios were 1.14, 1.09 (4.8% reduction), and 1.01 (12% reduction) kg of CO 2-equivalents (CO 2-eq)/kg of FPCM across US regions. The greatest carbon footprint for the baseline scenario was in the Southeast (1.26 kg of CO 2-eq/kg of FPCM) and lowest for the West region (1.02 kg of CO 2-eq/kg of FPCM). Enteric CH 4 reductions were 12.4 and 31.0% for the nitrate and 3-NOP scenarios, respectively. The uncertainty analysis showed that carbon footprint values ranged widely (0.88-1.52 and 0.56-1.84 kg of CO 2-eq/kg of FPCM within 1 and 2 standard deviations, respectively), suggesting the importance of site-specific estimates of carbon footprint. Considering that 101 billion kilograms of milk was produced by the US dairy industry in 2020, the potential net reductions of GHG from the baseline 117 billion kilograms of CO 2-eq were 5.6 and 13.9 billion kilograms of CO 2-eq for the nitrate and 3-NOP scenarios, respectively.
... For example, cultivating soybean for silage after a mixture of winter cereal and legume forages makes it possible to harvest more than 15 t DM/ ha per year (Tabacco and Comino 2019). GWP obtained for lucerne hay was similar to the one reported by Adom et al. (2012), 170 kg CO 2 eq/ton DM, but lower than the one reported by Fathollahi et al. (2018). This previous study found a value for the GWP of maize silage (329 CO 2 eq/ton DM) similar to the present study. ...
... This previous study found a value for the GWP of maize silage (329 CO 2 eq/ton DM) similar to the present study. On the opposite, GWP of maize silage was slightly higher compared to the result obtained by Xu et al. (2018), 680 kg CO 2 eq/ton AF, as well as to the data of Adom et al. (2012) and Mogensen et al. (2014), 200 and 224 kg CO 2 eq/ton DM, respectively. Compared to the studies mentioned above, the difference can be explained by the organic fertilisation of the maize silage of the present study and subsequent emissions into the air. ...
... In this regard, it is important to apply crop management strategies that can lower the GWP. For example, as Adom et al. (2012) suggested, fertiliser best management practices such as precision application of farm nutrients may significantly reduce maize GWP. Despite the high environmental impact of high moisture ear maize (Table 5), SBS diet, characterised by a higher inclusion of this feed than CON, showed lower GWP than CON. ...
Soybean meal, the main protein source for livestock in Italy, is associated with high environmental impact in terms of land use change. Thus alternative protein sources are advisable. The study aimed to evaluate through a Life Cycle Assessment (LCA) approach the environmental impact of milk production systems characterised by different diets of lactating cows including different sources of soybean. Four scenarios were identified: (1) conventional soybean meal (CON), (2) conventional soybean meal and soybean silage (SBS), 3) responsible soybean meal defined by the FEFAC guidelines (CON + RSM), (4) soybean silage and responsible soybean meal (SBS + RSM). Inventory data were derived from a previous in vivo trial on lactating cows and farmer interviews. Secondary data were obtained from the ECOINVENT® and the Agri-footprint databases. The LCA was performed using the SimaPro V 8.3. Soybean silage showed higher global warming potential (GWP), marine eutrophication and human toxicity compared with lucerne hay, the most utilised self-produced protein feed, due to the high contribution of mechanical operations in the field. The GWP of milk (kg CO2eq/kg FPCM) decreased from 1.38 of the CON scenario to 1.17 of SBS and 1.13 of CON + RSM; the best result was obtained by combining soybean silage with responsible soybean meal: 1.01. Furthermore, the scenarios using RSM reduced agricultural land occupation and natural land transformation. The inclusion of SBS and RSM is an interesting option to reduce environmental impact of milk production, maximising yields of DM and CP per hectare and representing an alternative protein source.
• HIGHLIGHTS
• The ration of dairy cows represents one of the main causes of the environmental impact of the livestock sector due to the impact for feed production (forage and concentrate)
• Feeding soybean meal as protein source has high environmental impact since it is linked with deforestation in South America
• Alternative protein sources like soybean silage and soybean meal produced sustainably could reduce the environmental impact of the sector
... Extensive work had been performed to assess the environmental impacts associated with corn ethanol (Hill et al. 2006;Shapouri et al. 2010;Wang 2001) and DDGS production (Hill et al. 2006). As a result of this work, Adom et al. (2012) developed emission factors for energy, mass based, and economic allocation as well as system expansion of DDGS as a by-product of corn ethanol production in the USA. These allocation factors utilized in the present study were 1.6 kg CO 2 e/kg DDGS for energy, 2.3 kg CO 2 e/kg DDGS for mass, 0.91 kg CO 2 e/kg DDGS for economic, and 0.53 kg CO 2 e/kg DDGS for system expansion. ...
... Nitrogen remaining from corn rotation with soybean was assumed to be 18.1 kg N/acre based on data from O' Leary et al. (2013). Nitrogen required to meet the yield was 0.540 kg N/bushel (bu) of corn produced (Adom et al. 2012). The difference between N requirement to meet yield and total N applied to soil was used to determine the amount of N required from manure application. ...
... A detailed list of all emission factors are given in Table 3. Emission factors used were in accordance with LEAP guidelines (FAO 2016a). Factors were sourced primarily from the Ecoinvent™ database in SimaPro 7.1 (SimaPro 2009) and Adom et al. (2012). While the UDSA NASS database provided N fertilizer input data for corn, it did not specify the types of N fertilizer being applied to corn. ...
Purpose
A life cycle assessment was performed for the production of a total mixed ration (TMR) fed to finishing feedlot cattle in California, USA. The goal was to determine the climate change impact of the feed supply chain associated with the production of 1 kg finishing TMR (kg CO2e/kg TMR). A secondary goal was to compare the climate change impact of feed versus finished beef (kg CO2e/kg live weight).
Methods
The TMR was based on feeds commonly fed to finishing cattle in California. The Livestock Environmental Assessment and Performance Partnership (LEAP) guidelines were followed for inventory data collection. System boundaries included the production of crops and feed additives, transportation of TMR components, and compound feed production. Data were sourced from national databases and Ecoinvent™ unit process data. Three scenarios were assessed as a result of allocation at the transportation step: Scenario A (100% empty return load); Scenario B (50% empty return load): and Scenario C (0% empty return load). Energy, mass, and economic allocation, and system expansion of dried distillers grain solubles (DDGS) were assessed for sensitivity analysis. Total feedlot emission data from Stackhouse-Lawson et al. (2012) were used to compare to impacts of TMR production.
Results
Total emissions were determined to be 0.630 kg CO2e/kg TMR for Scenario A, 0.576 kg CO2e/kg TMR for Scenario B, and 0.521 kg CO2e/kg TMR for Scenario C. Corn production, transportation, and liquid premix production were primary contributors to the life cycle impacts of TMR production. Mass-based allocation of DDGS was found to have the most significant effect on overall impacts of the finishing TMR, with a 42% increase in life cycle emissions compared to other allocation methods. For Scenario A, feed used in Angus feedlot production contributed to 76% of total Angus feedlot emissions. Additionally, feed used in Holstein feedlot production contributed to 58% of total Holstein feedlot emissions.
Conclusions and recommendations
The present study demonstrates a need to better assess the feed supply chain of feedlot beef production in order to accurately identify areas that have the most significant impacts on overall emissions. This may aid in minimizing impacts associated with feed production and, by extension, beef production. The present study may also serve to inform future decisions for improvements or alterations of the LEAP guidelines.
