Greenhouse gas emissions from the enteric fermentation and manure storage of dairy and beef cattle in China during 1961-2010.

Due to the expanding dairy and beef population in China and their contribution to global CH4 and N2O budgets, a framework considering changes in feed, manure management and herd structure was established to indicate the trends of CH4 and N2O emissions from the enteric formation and manure storage in China׳s beef and dairy production and the underlying driving forces during the period 1961-2010. From 1961 to 2010, annual CH4 and N2O emissions from beef cattle in China increased from 2.18Mt to 5.86Mt and from 7.93kt-29.56kt, respectively, while those from dairy cattle increased from 0.023 to 1.09Mt and 0.12 to 7.90kt, respectively. These increases were attributed to the combined changes in cattle population and management practices in feeds and manure storage. Improvement in cattle genetics during the period increased the bodyweight, required dry matter intake and gross energy and thus resulted in increased enteric CH4 EFs for each category of beef and dairy cattle as well as the overall enteric EFs (i.e., Tier 1 in IPCC). However, for beef cattle, such an impact on the overall enteric EFs was largely offset by the herd structure transition from draft animal-oriented to meat animal-oriented during 1961-2010. Although the CO2-eq of CH4 and N2O from manure storage was less than the enteric emissions during 1961-2010 in China, it tended to increase both in beef and dairy cattle, which was mainly driven by the changes in manure management practices.