Effect of improving Diet Quality by Feeding Supplements on Methane Emission in different Production Systems of Beef Cattle in Brazil

In Brazil, the national inventories on methane emission are carried out using the Tier 2 approach published by the Intergovernmental Panel on Climate Change (IPCC). Although, IPCC recommends the use of a more specific Tier 3 approach, this is hampered by a lack of consolidated data for development, evaluation and application of such a Tier 3 approach. The purpose of this study was to estimate the effect of improving diet quality by feeding supplements on methane emission, calculated by both a Tier 2 and an extant Tier 3 approach, in different production systems of beef cattle in Brazil: (1) high quality diet and feedlot feeding from weaning to slaughter- FSFF - Feedlot finishing (14 mth); (2) energy and protein supplementation - ESPF - Pasture finishing (20 mth); (3) protein supplementation during dry and wet season - PSFF - Feedlot finishing (24 mth); (4) protein supplementation dry at first and second dry seasons combined with ad libitum mineral salt supplementation and protein supplementation wet at first and second wet season, respectively- PSPF - Pasture finishing (30 mth); (5) urea supplementation with mineral salt during the dry season and ad libitum salt during the wet season - USFF - Feedlot finishing (36 mth); (6) urea salt during the dry season and ad libitum mineral salt during the wet season - USPF - Pasture finishing (44 mth). Tier 2 and Tier 3 approaches estimated a profound effect of supplementation on methane emission. Tier 2 estimates ranged from 168 (USPF) to 35 kg per animal (FSFF) while Tier 3 estimates ranged from 145 (USPF) to 32 (FSFF) kg per animal. Using a Tier 3 approach for Brazilian conditions led to lower predictions of enteric methane compared to the IPCC Tier 2 approach. This study is part of the FP7 AnimalChange project (Grant Agreement 266018) and co-financed by the Dutch Ministry of Economic Affairs (KB-12-006.04-003). The first author also acknowledges the financial support of the Capes (Cordena¸c˜ao de Aperfei¸coamento de Pessoal de N´ivel Superior) for granting a graduate scholarship (2013/9820/12-4), besides financial support for training at Wageningen University Research Centre.