Table 3.
Estimated enteric fermentation emission factors (EF) for sheep. The ryegrass and permanent pasture values were generated based on measured mean emission rates per day for Welsh Mountain and Texel cross lambs aged 3–4 months old
| EF | Reference | |
|---|---|---|
| Published | ||
| Mature sheep (>1 year old) | 8·0 kg CH4/head/year | Dong et al. (2006) |
| UK Lambs* | 2·2 kg CH4/head/year | Webb et al. (2013) |
| Current study | ||
| Ryegrass (for 12 month period) | 5·9 kg CH4/head/year | |
| Permanent pasture (for 12 month period) | 4·7 kg CH4/head/year | |
| Ryegrass (for 8·1 month lifespan) | 4·0 kg CH4/head/year | |
| Permanent pasture (for 8·1 month lifespan) | 3·2 kg CH4/head/year | |
Methane, CH4
*
Assumes emission factor is 0·4 of that of an adult sheep and the average lifespan of lambs is 8·1 months.