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This paper aimed to review the nitrogen emissions from the agriculture and livestock sector and their impact on the environment in the light of the actual global climate change picture. Emissions of ammonia, nitrogen oxide and nitrous oxide contribute to air pollution and global warming, while nitrates contribute to soil and water pollution. The agriculture and livestock sector is responsible for ammonia emissions representing approximately 80-90% of total anthropogenic emissions. Approximately 52% of total nitrous oxide emissions are coming from agriculture, and there is a strong correlation with the application rates of synthetic fertilizers. The nitrogen lost in the soil and water through leaching represents an important nitrate emission with negative effects on the environment due to acidification and eutrophication. As a result of human activity in recent decades, significant amounts of reactive nitrogen were released into the environment, disrupting the natural nitrogen cycle. The main causes of nitrogen emissions in the agriculture and livestock sector are represented by the excessive and inefficient use of synthetic fertilizers, manure management, including the low efficiency of nitrogen conversion into milk, meat and eggs by animals. [ABSTRACT FROM AUTHOR]

This paper aimed to review the literature concerning nitrogen metabolism and excretion in dairy cows in the light of actual global climate change picture. Nutritional factors like dietary crude protein or dietary carbohydrate concentration have a significant effect on nitrogen balance, through the decreasing capacity of the total N excretion and improving the milk nitrogen efficiency. At the same time, the protein and carbohydrate degradability rates as well as dietary minerals will impact the excretion routes, urinary and faecal. Shifting between urinary to faecal pathway could benefit to the mitigation of air pollution as the faecal nitrogen content is less prone to volatilisation compared to the urine nitrogen. Feed additives such as direct feed microbial, plant secondary metabolites and rumenprotected amino acids can mitigate and shift the N excretion from the urinary to the faecal pathway. Finally, breeding animals for lower MUN traits could also be considered as an efficient approach for a longer-term strategy to reduce N emissions. [ABSTRACT FROM AUTHOR]