Relationships between Feed Efficiency and Gas Emissions in Beef Cows Managed in Drylot and on Pasture

Abstract

Estimating feed efficiency and greenhouse gas emissions for mature beef cows on pasture faces technical challenges, along with little information on the consistency of enteric emissions between dry lot and pasture. This research examined relationships amongst feed efficiency, enteric methane (CH4), and carbon dioxide (CO2) for beef cows in drylot and on pasture. The trial first monitored feed intake, CH4 and CO2 production, weight, and backfat depth every 28 days for 10 weeks for 64 pregnant multiparous beef cows in drylot. Post-calving, cows were randomly assigned to paddocks, and enteric emissions and performance were measured over the grazing season. Results demonstrated animals with low RFI and RFI adjusted for backfat depths had lower intake per kg BW, CH4 and HP calculated from the respiratory quotient in drylot. There were moderate correlations between gas emissions in drylot and on pasture, demonstrating that drylot emissions could be predictive of emissions on pasture.