Quantification of ammonia emissions from dairy and beef feedlots in the Jing-Jin-Ji district, China

•NH3 emissions from China’s dairy and beef feedlots were provided in the first time.•Both temperature and wind speed play important role in the diel NH3 variation.•NH3 emission factors for dairy and beef cattle in China were obtained.•Dairy cattle in feedlots tended to have greater NH3 rates than cattle in barns.