Is methane production likely to be a future Merino selection criterion?

Selection index theory was used to model the effects of including feed intake and methane (CH₄) production in the breeding objective and having both, either or none of these traits as selection criteria on genetic responses in Merino production traits. A range of economic values (EV) were assumed for CH₄ production based on expected future prices for CO₂-e ($/tonne). The implicit price of carbon required to achieve desired gains of a reduction in CH₄ of 1% p.a. were calculated. The sensitivity of desired gains to changes in the correlations between production traits and CH₄ production were modeled as these correlations are currently unknown. If the correlations between production traits and CH₄ are positive (as expected) then it is very unlikely that CH₄ production would be used as a selection criterion as an implicit carbon price of over $400/tonne CO₂-e was needed to achieve the desired reductions in CH4 production. However, if the correlations are unexpectedly negative, the carbon price needed to achieve such gains was more likely at ~$30/tonne CO₂-e. The correlations need to be determined from research trials for informed advice about breeding for CH₄ reduction to be given to Merino breeders.