Qian Liu1, Jingmeng Wang1, Zhaohai Bai2, Lin Ma2, Oene Oenema1,#
1 Wageningen University, Environmental Sciences, PO Box 47, NL-6700 Wageningen, Netherlands
2 Center for Agricultural Resources Research, Chinese Academy of Sciences, 286 Huaizhong Road, Shijiazhuang 050021, China
# Email: email@example.com
This paper briefly reviews the changes in global animal production during the last 50 years, when total production has roughly tripled. Cattle dominate the world in terms of animal biomass but pigs and poultry increase faster in number and production. Animal production systems are highly diverse across the world, and have a relatively large impact on the environment through emissions of greenhouse gases and ammonia to the atmosphere and nutrients (mainly nitrogen and phosphorus) to water bodies. Losses greatly depend on system, management and regulations. The total amounts of nitrogen and phosphorus in manure produced annually are larger than the global use of synthetic fertilizer annually, but manure nutrients are often not used efficiently. Nitrogen use efficiency (NUE) at animal level ranges from 5 to 45%, depending on animal category, feeding and management. NUE at crop-animal system level may range from 5 to 65% depending on NUE at animal level and the utilization of manure nitrogen and new nitrogen inputs. It is a huge challenge to increase NUE at animal and system levels globally and to diminish the environmental impacts.