Short communication: Genetic correlations between methane and milk production, conformation, and functional traits.

Livestock produce CH, contributing to the global warming effect. One of the currently investigated solutions to reduce CH production is selective breeding. The goal of this study was to estimate the genetic correlations between CH and milk production, conformation, and functional traits used in the selection index for Polish-Holstein cows. In total, 34,429 daily CH production observations collected from 483 cows were available, out of which 281 cows were genotyped. The CH was measured using a so-called sniffer device installed in an automated milking system. Breeding values for CH were estimated with the use of single-step genomic BLUP, and breeding values for remaining traits were obtained from the Polish national genomic evaluation. Genetic correlations between CH production and remaining traits were estimated using bivariate analyses. The estimated genetic correlations were in general low. The highest values were estimated for fat yield (0.21), milk yield (0.15), chest width (0.15), size (0.15), dairy strength (0.11), and somatic cell count (0.11). These estimates, as opposed to estimates for the remaining traits, were significantly different from zero.