Genetic variability of methane production and concentration measured in the breath of polish holstein-friesian cattle

Abstract

The genetic architecture of methane (CH4) production remains largely unknown. We aimed to estimate its heritability and to perform genome-wide association studies (GWAS) for the identification of candidate genes associated with two phenotypes: CH4 in parts per million/day (CH4 ppm/d) and CH4 in grams/day (CH4 g/d). We studied 483 Polish Holstein-Friesian cows kept on two commercial farms in Poland. Measurements of CH4 and carbon dioxide (CO2 ) concentrations exhaled by cows during milking were obtained using gas analyzers installed in the automated milking system on the farms. Genomic analyses were performed using a single-step BLUP approach. The percentage of genetic variance explained by SNPs was calculated for each SNP separately and then for the windows of neighbouring SNPs. The heritability of CH4 ppm/d ranged from 0 to 0.14, with an average of 0.085. The heritability of CH4 g/d ranged from 0.13 to 0.26, with an average of 0.22. The GWAS detected potential candidate SNPs on BTA 14 which explained ~0.9% of genetic variance for CH4 ppm/d and ~1% of genetic variance for CH4 g/d. All identified SNPs were located in the TRPS1 gene. We showed that methane traits are partially controlled by genes; however, the detected SNPs explained only a small part of genetic variation—implying that both CH4 ppm/d and CH4 g/d are highly polygenic traits.