Feed use and nitrogen excretion of livestock in EU-27

Livestock excreta is a large source of nitrogen (N) in the European Union (EU), used to fertilize crops, and also a main source of ammonia (NH₃), nitrous oxide (N₂O) and nitrate (NO₃^-) losses to the environment. The amount of N in excreta mainly depends on the animal category and productivity, and on feed use and management. National inventories of emissions to the environment are often based on different methodologies for the estimation of N excretion. Here, we present a transparent and uniform methodology for estimating annual feed use and N excretion per animal category for all countries of the EU-27, based on the energy and protein requirements of the animals and statistics of feed use and composition, animal number and productivity.The calculated total feed use in the EU-27 was 506Tg dry mass in 2010. Dairy cows used 29%, other cattle 34%, pigs 17%, chicken 9%, sheep and goats 8%, and other animal categories 3% of the total feed use. Grass and annual forages were mainly used by dairy cows (30 and 49%, respectively) and other cattle (55 and 44%); pigs used most of the feed cereals (53%); protein-rich feed (e.g., soybean meal) were mostly used by pigs (34%) and chicken (24%). Differences between countries in feed use were large, mainly related to variations in national feed supply and animal productivity. Total N excretion of the animals amounted to 9.7Tg in 2010, and varied between countries from 14 to 291kgha^-1 of utilized agricultural land. The present study provides a uniform and transparent approach for evaluating feed use and N excretion in all countries of the EU-27. Our results underline the significant differences in N excretions between EU countries as a result of feed use variations, suggesting the need for basing N excretion estimations on feed use data. The dataset present in this study may serve as a basis for such efforts, also to improve national inventories of N emissions.