Animal breeding and climate change, mitigation and adaptation
Martino Cassandro
Abstract
The future of livestock will be driven by the continued increase in the global human population, by unequal distribution of wealth and by the continued increase in demand for livestock products that are highly nutritious and socially sustainable. High competition with other uses of land and water resources is expected and hence more socially acceptable, efficient and sustainable livestock production will be needed. Climate change, environmental mitigation and animals adaptation are emerging topics in the sector of animal breeding and they impose new breeding goals and new research. Global average temperature has increased by about 0.7°C in the last century. The Intergovernmental Panel on Climate Change (IPCC) reported that anthropogenic greenhouse gases (GHG), including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and halocarbons, have been responsible for most of the observed temperature increase. Agriculture, particularly livestock, is increasingly being recognized as both a contributor to the process and a potential victim of it. Policy interventions and technical solutions are required to address both the impact of livestock production on climate change and the effects of climate change on livestock production. The Food and Agriculture Organization (FAO) declared that within 2050, farmers will be called upon to produce more food than has been produced in the past 10,000 years, and to do so in environmentally sustainable way. Therefore, the GHG reduction has to be treated as a public good. The United States Congress is prospecting to define a price on GHG emissions, and the Australian government introduced a carbon pricing scheme or "carbon tax" through the Clean Energy Act 2011. However, although Australia has achieved a reduction in the country's carbon emissions, the initiative faced significant challenges from the opposition and the public, as it resulted in increased energy prices for both households and industry and was finally repealed in 2014. Recently, a climate movement, as the Global Climate Movement led by Greta Thunberg, are a clear example of how hundreds of thousands of young people ask the global leaders for environmental actions, shaking the consciences of citizens in various countries around the world. Limiting the concentration of GHG in the Earth's atmosphere requires a technological, social and economic revolution. A cost-effective way is genetic improvement which produces permanent and cumulative changes in livestock performance. Animal variation of enteric CH4 emission has been reported in the literature, providing potential for improvement through genetic selection. Livestock contributes to climate change by emitting GHG, either directly from enteric fermentation or indirectly through, for example, feed-production activities, deforestation and manure. Greenhouse gas emissions can arise from all the main steps of the livestock production cycle, but the amount emitted varies with animal species. Johnson and Johnson (1995) estimated the contribution of cattle to global warming that may occur in the next 50 to 100 years to be approximately 2%. Emissions from feed-crop production and pastures are linked to the production and application of chemical fertilizers and pesticides, to soil organic-matter losses and to transport. When good management practices are implemented on degraded land, pasture and cropland can turn into net carbon sinks, sequestering carbon from the atmosphere. Recent conclusions, discussed at the 3rd Agriculture and Climate Change Conference 2019 in Budapest (Hungary), reported that the CO2 subtracted from the atmosphere by the vegetables cultivated to feed livestock is about four times higher than the sum of CO2 equivalents emitted by agricultural processing, physiological ruminal fermentations and dejection management (De Vivo and Zicarelli, 2019). Each country, region and farming system in the future will need to estimate its balance between carbon emission and carbon sink. Understanding adaptive ability of livestock is a key factor in the context of global climate change and becomes a crucial factor in conservation and management for a sustainable farming in a changing environment. One way to better understand adaptive ability is to identify genes underlying adaptation phenotypes. This goal can be achieved by genetically characterizing livestock species and detecting footprints of selection in the animal genome. Several recent investigations on the genetic regions with a potential adaptive role in high productive specialized breeds and several autochthonous populations reared in different environments have been published. Also, a number of analyses have been performed to detect footprints of selection and genomic regions associated with climate variables. Clear footprints of cattle selection detected on BTA6 and BTA18 are pointing out several candidate genes (LCORL, PDGFRA, KDR and SPG7); moreover, different genomic regions on BTA6, BTA10, BTA19 and BTA20 are associated with annual mean radiation. Ongoing and future research will specify candidate regions and genes involved in adaptation in different rearing environments. In conclusion, the livestock sector has tremendous potential to contribute to climate change mitigation and adaptation. Realizing this potential will require new and extensive initiatives at the international level including the promotion of research on and development of new mitigation technologies; effective and enhanced means for financing livestock activities; deploying, diffusing and transferring technologies to mitigate GHG emissions; and enhancing capacities to monitor, report and verify emissions from livestock production. The new goals of livestock sector should account for environment safeguard and climate changes, as limitation of GHG. The application of technologies that improve the efficiency of land and feed use can mitigate the negative effects of livestock production on biodiversity, ecosystems and global warming. Hence, genetic improvement of livestock population is a cost-effective strategy to mitigate climate change and improve the adaptive ability of livestock animals to new environments. The community of animal breeders must be able to drive the livestock population to conjugate quality and efficiency of production in different challenging environments under continuous evolution by using modern tools such as artificial intelligence, epigenomics, and possibly genome editing, in a holistic and cost-effective approach.