As part of the Master’s in Sustainable Tropical Agriculture program (MATS), Zamorano students conduct applied research with the help of international experts from world-renowned universities.
By: Dikson Marin López, (MATS-ZAMORANO)
Email: [email protected]
Livestock contributes 14.5% of greenhouse gases (GEI) globally. Of this total, emissions of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), represent 27%, 44% and 29% respectively (Gerber et al. 2013). When calculating the carbon dioxide equivalent (CO2-eq), enteric fermentation is the major contributor to this area (39.1%), followed by manure handling, both its application and direct deposit (25.9%), food production (21.1%), land use change (9.2%), post production (2.9%), and use of direct and indirect energy (Gerber et al. 2013). Total emissions of worldwide livestock amount to 7.1 Gt CO2-eq/ per year. The Latin American and Caribbean regions represent the highest levels globally with almost 1.8 Gt CO2-eq. These high emissions from the region are driven largely by specialized meat production which has led to changes in land usage for the expansion of grasslands and agricultural lands for concentrated production (Gerber et al.2013).
Emission rates described above were calculated using the Cycle of Life Analysis methodology (ACV), which is all-encompassing, from product conception straight through to the retail market (Sala et al. 2017). The GEI emissions are calculated to include the production of concentrated livestock products, animal husbandry, processing and transportation to markets (Bakken et al. 2017).
Based on this methodology, Histrov et al. (2013) determined that meat production (41%) and dairy (20%) are the largest contributors to GEI emissions from the livestock sector worldwide. Using the ACV we can determine the carbon footprint (HC) of livestock products. This can be defined as the sum of GEI emissions and removals related to production, the transformation and the marketing of meat and milk.
HC calculations begin with the determination of system limits, which encompass, according to Sala et al (2017), the “cradle-to-grave”. At the same time, the functional units are pre-set, so a comparison can be made between determined results across studies. In dairy system studies, it is common to find functional units such as 1 kilogram (kg) of milk, 1 kg of protein and 1 kg of corrected milk for fat and protein. The International Dairy Federation (IDF) recommends this last unit. Knowing the HC of produced milk in cattle herds of Latin America and the Caribbean affords us a starting point for generating mitigation strategies. This would enable goal-setting for the improvement of animal performance programs in tropical countries to satisfy the demand of animal protein and at the same time achieve a reduction of emissions of GEI thereby realizing efficiencies in the use of natural resources (Rao et al. 2015)
According to Havlik et al (2014) and Herrero et al (2013), the HC of ruminants intended for milk production vary between 12-140 kg CO2-eq/kg of protein. Gerber et al. (2013) calculated that the average worldwide emissions per kg of dairy protein is below 100 kg CO2-eq. We also know that Thoma et al. 2013 determined that the GEI emissions per kg of protein from bovine milk was 61kg CO2-eq. In West Africa Kiggundu et al. (2019) estimated 75.9 kg CO2-eq/kg of protein in bovine milk production systems.
Dairy protein emissions in Honduras
Recently, in Honduras, Marin-Lopez et al. (2020), registered emissions per kg of dairy protein across five different regions in the country, with results spanning 79 to 96 kg CO2-eq. These figures were similar to the ones presented by Gaitan et al. (2016) in Nicaragua who compared three conventional production systems and found that they produced an average of 66-86 kg CO2-eq, compared to 47 kg CO2-eq reported in forest pasture systems with 77% of fodder trees in the rotational grazing area. Also, Vega (2016) measured for double purpose systems in Costa Rica an average of 66.5 kg CO2-eq, while in Colombia, Rivera et al (2016) reported 47.3 and 58.3 kg CO2-eq/kg of protein in forest pasture and conventional systems, respectively.
The studies cited above only calculate the GEI emissions based on the HC of 1 kg of dairy protein. However, diverse studies have shown the importance of including GEI removals, mainly the removal of carbon from soil as well as forest biomass (Stanley et al. 2018; Ramirez-Restrepo et al. 2019). When removals of carbon are considered and subtracted from emissions of GEI, the HC, values obtained are often lower than to the ones reported in studies where only emissions are considered. In some cases, the values can even be negative, indicating that the carbon removed is larger than the carbon emitted (Stanley et al. 2018; Ramírez-Restrepo et al. 2019; Resende et al. 2019).
In Latin America and the Caribbean, livestock systems base their meat and dairy production on the direct use of pastures. 93% of Brazilian cattle is pasture-fed, which means lower feeding costs compared to countries such as the US where stable systems prevail (Ferraz y Felício 2010). You find the same situation in Honduras, where pasture-fed cattle predominates, generally making use of extensive grazing systems (Canu et al. 2018). Taking into consideration the potential that Carbon from soil dedicated to grazing, proper management can be a long term valuable mitigation tool for tropical livestock systems (Stanley et al. 2018).
Thus, future studies in the region must include flow dynamics of Carbon in soil and forestry biomass to obtain, not only a real balance between GEI emissions and the capture of carbon, but also develop a unique HC for each country´s dairy system and their products. Being able to increase the region´s cattle herds in parallel with a decrease in the production of HC must be the goal when designing projects and governmental policies. It is necessary to continue conducting research on environmental impact which on local and worldwide levels generates sustainable and fair rural development and increases opportunities for food security.
To learn more about the Master’s In Sustainable Tropical Agriculture (MATS), and for information regarding registration:
MATS is Zamorano’s flagship program in applied research, aligned with the University’s vision of development and innovation. This Master’s program has afforded the university an opportunity to expand its graduate academic offerings as well as its influence on regenerative agriculture, a pillar of humanity.
MATS is Zamorano’s flagship applied research program, aligned with a vision of development and innovation. This master’s degree has allowed the university to expand its academic offerings to the postgraduate level and influence regenerative agriculture because it is the pillar of humanity.
References:
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