Resumo

MORANTE LOPEZ, Daniela et al. Tier II estimation of enteric methane emission in dairy cow herds in Querétaro, México. Rev. mex. de cienc. pecuarias [online]. 2016, vol.7, n.3, pp.293-308. ISSN 2448-6698.

Methane (CH4) contributes to climatic change and livestock enteric fermentation is the most important anthropogenic source. The Intergovernmental Panel on Climate Change establishes continental default emission factors for enteric methane (Tier I); but decisions and evaluation of mitigation needs more precise estimates. Therefore, the objective was to calculate the enteric emission of Holstein-Friesian herds in Queretaro, México using milk test-day records (Tier II). Lactation curves were modeled using the incomplete gamma function according to lactation number and herd. A total of 11,092 lactations from 2007 had an average 305 d milk yield of 9,985 kg. Lactation curve was different between primiparous and multiparous; average days in milk were 365±21 d. During lactation, the primiparous and multiparous enteric emission at 305 d was 165.7±3.8 and 181.6±8.3 kg CH4 head-1; at 365 d was 201.8±4.6 and 223.7±11.0 kg CH4 head-1 (P<0.0025). Enteric emission intensity was similar between primiparous and multiparous (18 and 19 g CH4 kg-1 milk), similar to reports in the literature for high yielding cows. Test day records were useful to characterize yield, days in milk and parity influencing the estimates of enteric emission intensity.

Palavras-chave : Climatic change; Emission factor; GHG; Mitigation; Methane.