Heritability of methane emission in young Norwegian Red bulls estimated from GreenFeed measures at the test station

Abstract

The aim of this study was to estimate heritability of methane (CH₄) emissions for young Norwegian Red bulls. Measures of CH₄ from a GreenFeed (GF) unit at Geno’s test station for young bull was available. Bull calves arrive the test station 3-4 months old and are grouped in pens with on average 10 calves. Methane is measured the last 1-2 months before they leave the test station, at 11-12 months age. On average each bull had 40 days with CH₄ data. We used data recorded from September 2020 to April 2023 and the final dataset had records from a total of 76 094 GF visits from 212 bulls. The mean (standard deviation) was 218 (50) gram CH₄ per bull per day. The traits analyzed were gram CH₄ per day, measured per GF visit or computed as the average of the bull’s individual visits each day. A linear animal repeatability model with fixed effects of age and group-testday, and random effects of animal and permanent environment were used to estimate variance components. The estimated heritability (standard error) was 0.24 (0.10) for CH₄ per visit and 0.56 (0.20) for CH₄ mean per day, with repeatability of 0.32 and 0.71, respectively. The predicted breeding values for bulls with phenotype varied from -37 to +60, with standard errors ranging from 12 to 15. Results so far are promising, the genetic variation for CH₄ in the Norwegian Red breed indicates that breeding for lower methane emission is feasible.