PSLBII-20 Estimation of genetic parameters for methane emissions and residual feed intake in Nellore cattle

Abstract

Abstract The objective of this study was to obtain (co)variance components, heritability, and genetic correlation estimates for enteric methane emissions, residual feed intake, growth, carcass and reproductive indicator traits. Data from 43 feed efficiency trials conducted over a 13-yr period on a single purebred Nellore herd in Central Brazil, comprising 3,400 intact males and 2,167 females, were analyzed. Trial data along with diet NDF content were used to estimate the methane emission (g CH4/kg carcass gain) for each individual, using an equation developed by Medeiros et al., 2014: CH4 (g/d) = -0.1011 + 0.02062*DMI (kg/d) + 0.001648*NDF (% of DMI). Other data included pedigree information, body weight (BW), carcass traits, and reproductive indicator traits. Continuous traits were analyzed using a linear animal model, and threshold traits were analyzed using a threshold animal model. Two-trait analyses were performed using the restricted maximum likelihood to estimate the variance components, heritabilities and genetic and phenotypic correlations among traits. The estimated heritability of methane emissions was 0.136 ± 0.0314. The genetic correlations of methane emissions with growth and carcass traits were low and not different from zero: BW at 450 d (0.064 ± 0.140), scrotal circumference at 365 d (0.188 ± 0.155), longissimus muscle area (-0.090 ± 0.132), 12th-13th rib fat (-0.122 ± 0.142), rump fat (0.080 ± 0.119), intramuscular fat % (-0.108 ± 0.152), BW at 210 d (-0.077 ± 0.168). By contrast, there were the low genetic correlation of methane emissions with early calving probability (-0.260; -0.504 – 0.026); moderate genetic correlations of methane emissions with age at first calving (0.519 ± 0.202) and DM intake (0.512 ± 0.116); and the high correlation of methane with residual feed intake (RFI; 0.832 ± 0.073). Thus, selection to improve weaning and yearling weights, and carcass traits would not affect methane emissions. Genetic selection to reduce methane emissions is feasible and would also reduce DMI and RFI, as well as female sexual precocity traits. Conversely, selection to improve RFI can be used to identify animals with decreased methane emissions. Medeiros, S. R, L. G. Baioni, A. Berndt, M. C. Freua, T. Z. Albertini, C. Costa Jr., e G. B. Feltrin (2014) Modeling enteric methane emission from beef cattle in Brazil: A proposed equation performed by principal component analyses and mixed modeling multiple regression. Proceedings, Livestock, Climate Change and Food Security Conference, Madrid.