This review aimed to present the main environmental impacts related to livestock, especially as regards the emissions of greenhouse gases (GHGs) and the possible ways to mitigate these externalities. The creation of ruminants in Brazil comes mainly extensively, often in areas of degraded pasture and hence low productivity. This fact enables the activity a great opportunity to reduce the impact to the environment, since actions taken to improve animal performance should result in a lower consumption of natural resources (land and water) and greater efficiency of the digestive system animal. The main problems identified by researchers in relation to cattle production are the methane emitted from enteric fermentation of ruminants, nitrous oxide emitted by feces of grazing animals and carbon dioxide exchanged by soil and vegetation. Many factors influence the production of CH4 from enteric ruminants, including the type of carbohydrate fermentation, the animal's digestive system, and the amount and type of food consumed. In this light, researchers have been working technologies to reduce methane emissions through improved food handling practices, manipulation of rumen by supplementation with monensin, lipids, organic acids and plant compounds. Other strategies to reduce methane that were investigated are defaunation and vaccines, which seek to inhibit methanogens and methanogenesis. Thus, the search for more efficient production systems has been one of the prospects of livestock worldwide, aiming to reduce emissions and increase animal production.
global warming; mitigation; rumen manipulation; ruminants