Genome-wide association study for mid-infrared methane predictions in Walloon dairy cows

This study aimed to identify genomic regions associated with two mid infrared-based CH4 traits [predicted daily CH4 emission (PME, g/d), and log-transformed predicted CH4 intensity (LMI)] in Walloon dairy cows. The data consisted of 1,529,282 test-day records from 229,465 cows distributed in 1,530 herds collected from 2006 to 2021. Random regression test-day models were used to estimate variance components. The proportion of genetic variance explained by windows of 50 consecutive SNPs was calculated and regions accounting for at least 1.0% of the total genetic variance were identified. Mean (SD) daily h2 estimated for PME and LMI were 0.14 (0.05) and 0.24 (0.05), respectively. Two regions on BTA14 (positions 1.86 to 2.12, and 1.48 to 1.68 Mb) were associated with both PME and LMI. A region between 144.38 to 144.46 Mb on BTA1 was associated with PME; and the region between 2.68 and 2.94 Mb on BTA14 was associated with LMI. Results showed potential for genome-enhanced advisory systems to reduce methane emissions.