According to the United Nations (UN 2017), the world population is increasing of about 83 million people annually. Due to this inevitable population growth the demand for livestock is also increasing. The livestock sector calls for a significant sum of natural resources and is responsible for anthropogenic greenhouse gas emissions. Modifying and adapting mitigation strategies to lessen emissions of this sector are needed to limit the environmental burden from food production.
The top greenhouse gases from animal agriculture are methane and nitrous oxide. Methane is a gas which has an effect on global warming 28 times higher than carbon dioxide and is mainly produced by enteric fermentation and manure storage. Nitrous oxide, is a molecule with a global warming potential 265 times higher than carbon dioxide arising from manure storage and the use of organic/inorganic fertilizers The carbon dioxide equivalent is a standard unit used to account for the global warming potential was adapted from the Global Livestock Environmental Assessment Model and shows in carbon dioxide equivalents the greenhouse gas incidences that enteric fermentation and manure storage have across the main livestock species raised worldwide.
In line with this, feed production together with the related soil carbon dioxide and nitrous oxide emissions is another important hot spot for the livestock sector. Soil carbon dioxide emissions are due to soil carbon dynamics, the manufacturing of synthetic fertilizers and pesticides, and from fossil fuel use in on-farm agricultural operations. Nitrous oxide emissions are emitted when organic and inorganic fertilizers are applied to the soil. Feed production and processing contribute about 45% of the whole sector. Enteric fermentation producing about 2.8 Gigatonnes (39%) is the second largest source of emissions. Manure storage with 0.71 Gigatonnes accounts for about 10% of the total. The remaining 6% (0.42 Gigatonnes of carbon dioxide equivalents) is attributable to the processing and transportation of animal products. Feed productionincludes all the greenhouse gas emission arising from a) land use change, b) manufacturing and use of fertilizers and pesticides, c) manure excreted and applied to fields, d) agricultural operations, e) feed processing, and f) feed transport.
The extreme heterogeneity of the agricultural sector needs to be taken into account when defining the overall sustainability of a mitigation strategy, which can vary across different livestock systems, species, and climates. Mitigations for Enteric Fermentation includes Improving Diet Digestibility by increasing concentrate feeding which reduces 15% of methane emission per unit of fat protein corrected milk, Addition of Fats or Fatty Acids to the diets of ruminants which decrease enteric methane emissions by both decreasing the proportion of energy supplied from fermentable carbohydrates and changes in the microbial population of the rumen, and lastly, Feed Additives. Mitigations under Manure Storage are frequent removal of manure, Solid-liquid Separation, Anaerobic digestion, balanced diet for amino acids for all animal species. Under Feed Production, mitigations devised are timing, quantity, and method of fertilizer applications. In Animal Management, improving cattle health is an effective way to reduce greenhouse gas emissions.
In conclusion, livestock production adds to global warming through emissions of methane and nitrous oxide. To supply the needs of the world, animal productivity will need to increase and seeks for greenhouse gas emission intensity per unit of product to decrease. Adopting an effective mitigation strategy is a must in order to achieve environmental standard. To increase the effectiveness of these strategies, complex interactions among the components of livestock production systems must be taken into account to avoid environmental trade-offs. Unfortunately, there is not a standard procedure to follow. Mitigation practices should not be evaluated individually, but as a component of the entire livestock production system. The majority of these strategies aim to increase productivity (unit of product per animal), which in most cases cannot be achieved without good standards of animal health and welfare. Optimizing animal productivity has a powerful mitigating effect in both developed and developing countries; however, the size of the effect will also depend on factors such as the genetic potential of the animal and adoption of management technologies.
Reference:
Giampiero G. (2018).LIVESTOCK AND CLIMATE CHANGE: Impact of Livestock on Climate and Mitigation Strategies. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7015462/
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Studies have shown that dietary manipulation with use of feed additives such as medicinal plants and essential oils have shown great prospects in mitigating enteric methane emissions in ruminant livestock.