Table 1.
Definition of traits
| Trait name | Abbreviation | Unit | Definition |
|---|---|---|---|
| Test period weight | TWT | kg | Weight at time of emissions test |
| Dry matter intake | DMI | kg/d | Dry matter intake during the emission test |
| Carbon dioxide production rate | CPR | g/d | Carbon dioxide produced |
| Methane production rate | MPR | g/d | Methane produced |
| Carbon dioxide yield | CY | g/kg | CPR per unit DMI (CPR/DMI) |
| Carbon dioxide to methane ratio | CM | Ratio of carbon dioxide produced to methane produced | |
| Residual carbon dioxide production | RCP | g/d | CPR net of expected CPR (expCPR) from the DMI, with expCPR obtained by regression of CPR on DMI |
| Residual methane production | RMP | g/d | MPR net of expected MPR (expMPR) from the DMI, with expMPR obtained by regression of MPR on DMI |
| Birth weight | BWT | kg | Weight at birth |
| Weaning weight | WWT | kg | Weight at weaning (~200 d of age) |
| Yearling weight | YWT | kg | Weight at yearling age (~400 d of age) |
| Final weight | FWT | kg | Weight close to maturity (~600 d of age) |
| Rib fat thickness | RIBFAT | mm | Subcutaneous 12/13 rib fat depth measured by ultrasound scanning |
| P8 rump fat thickness | P8FAT | mm | Subcutaneous rump fat depth measured by ultrasound scanning |
| Eye muscle area | EMA | cm2 | Cross-sectional area of the M. longissimus dorsi between the 12th and 13th ribs measured by ultrasound scanning |
| Intramuscular fat | IMF | % | Intramuscular fat measured by ultrasound scanning |