Emission of methane in livestock: cause-effect relationship and modulatory mechanisms

Abstract

Livestock farming has great importance in the Brazilian economic scenario, developed in all states and ecosystems of the country, and the Brazilian sector presents a wide range of production systems. Brazilian beef production is mainly from pasture production systems, with Brazil having an area of 180 million hectares of pasture, where more than half of this total presents some degree of soil degradation and pasture, mainly in stages advanced. The emission of methane by ruminants accounts for 22% of this gas in the atmosphere, making it the third largest source on a global scale. Methane gas (CH4) has a significant participation of 15% in global warming, but Brazil has a great potential to reduce the emission of methane gas by improving the productivity indexes of its livestock. Improvements in animal feeding and genetics result in less CH4 emission during the animal's life cycle. In addition, these improvements result in increased meat production resulting in a double benefit: the environmental and the economic. CH4 is considered to be the second largest contributor to the earth's heating by absorbing infrared radiation into atmosphere behind only carbon dioxide (CO2). The increase in its concentration in the atmosphere is closely linked to the worldwide expansion of the human population, since the main sources of emissions, besides enteric fermentation are landfills, fossil fuel use and agricultural practices. Thus, the objective of this review was to present the scientific literature about the production of methane bound to ruminants and to design modulatory mechanisms that allow the production of these animals with high production levels and low emission of this gas.