Balanço de gases de efeito estufa em sistemas de produção de bovinos de corte.

This simulation was develop aiming to estimate the emission of greenhouse gas (GHG) in different production systems, as well as the uptake by the pasture areas. Four hypothetical scenarios for beef cattle breeding systems were developed. The first system occurred in areas of degraded pastures, with production rates similar to Brazilian average (SMB), the second occurred in areas of well-managed pastures (SMP), the third occurred in a life-cycle raising systems, in which the first part of the raising took place in areas of well-managed pastures and the termination part was in feedlot (SMC), and the forth occurred in areas of well-managed pastures with protein and energy supplementation (SIP). The GHG sources considered were enteric and fecal methane, nitrous oxide from the wastes and carbon dioxide from agricultural and the animals' supplementation activities. The equations used to estimate the GHG production were based on the diet quality, animal performance and the duration of each cycle, using the Intergovernmental Panel on Climate Change (IPCC) method, level 2. The SMP showed higher emission with 199.748.72, followed by SMB, SMC and SIP with 151.012.17; 125.356.63 and 102.418.01 t CO2eq per production cycle, and their duration of 42, 30, 24 and 18 months, respectively. However, the individual CO2eq emission was higher in SMB, with 259.23 t CO2eq / animal. The relationship between CO2 emissions and carcass production was also lower for the more intensified systems. The adoption of more intensive production systems, the adoption of feedlot systems or supplementation through the entire cycle, proved to be more efficient both productive and environmentally, by reducing GHG emissions and increasing production per area. [ABSTRACT FROM AUTHOR]