Consequences of using different economic selection index methods on greenhouse gas emissions in beef cattle

Abstract

<p>The impacts of using partial (sub) indexes on expected greenhouse gas emissions (GHG) from a self-replacing cow herd producing 120-day grain-finished progeny is compared to selection with a full self-replacing BreedObject index. Sub-indexes only containing post-weaning traits of the slaughter progeny (terminal) and a maternal sub-index were developed using BreedObject. The terminal sub-index is expected to increase mature cow weight (MCW) and milk, resulting in increases in GHG emissions. In contrast, the full self-replacing index is expected to produce slight reductions in MCW and negligible change in milk, which results in decreases in GHG emissions of the cow herd and young animal at pasture. The maternal sub-index is expected to result in larger GHG emission reductions due to larger decreases in MCW as well as negligible change in milk. When constructing partial indexes, the implications on GHG emissions of the cow herd and progeny need to be carefully considered.</p>