1 Introduction
2 Methods
2.1 Goal and scope
2.2 Case study descriptions
Production system characteristics | CS 1 | CS 2 | CS 3 | CS 4 |
---|---|---|---|---|
Country | United Kingdom | New Zealand | Australia | Australia |
Sheep breed | Lleyn and Cheviot | Romney dominant | Merino, Meat Merino | Merino |
Wool and meat characteristics | ||||
Diameter (μm) |
c.30 | 32 | 21 | 17 |
Typical use | Interior textiles | Interior textiles | Outer garment | ‘near skin’ garment |
Typical lamb carcase weight (kg) | <20 kg dressed | <20 kg dressed | 20–24 kg dressed | <18 kg dressed |
Production details | ||||
Stocking rate (DSEa/ha) | 14.7 | 15.1 | 0.4 | 7.4 |
Ewe standard reference weight (kg) | 68 | 60 | 60 | 45 |
Lambing % (at marking) | 145 | 127 | 98.3 | 86.4 |
Annual wool clip (total kg greasy) | 3410 | 8236 | 10,619 | 6,219 |
Annual sheep sales (total kg LW) | 56,812 | 47,858 | 50,100 | 36,125 |
Total farm-gate production (greasy wool + LW) (kg) | 60,222 | 56,094 | 60,719 | 42,344 |
Whole flock wool production per breeding ewe (kg greasy) | 3.4 | 8.2 | 10.6 | 6.2 |
Resources and emissions | ||||
Arable land occupation (cultivated)—ha | 3.6 | 3.1 | 0.1 | 9.2 |
Arable land occupation (pasture)—ha | 3.6 | 24.6 | 0.0 | 16.2 |
Non-arable land occupation)—ha | 135 | 193 | 9,305 | 332 |
Total fossil fuel energy demand)—MJ oil-e b
| 457,668 | 310,734 | 290,376 | 259,475 |
GHG)—kg CO2-eb
| 581,796 | 477,384 | 525,089 | 442,889 |
Methane)—% of GHG | 72 | 77 | 88 | 84 |
Nitrous oxide)—% of GHG | 21 | 18 | 9 | 10 |
Carbon dioxide)—% of GHG | 7 | 5 | 3 | 6 |
2.2.1 Case study 1 (CS 1)
2.2.2 Case study 2 (CS 2)
2.2.3 Case studies 3 and 4 (CS 3, CS 4)
2.3 Inventory and impact assessment
2.3.1 Modelling feed intake and greenhouse gas emissions from livestock systems
Emission source | Unit | Sheep systems)—UK & NZ | Sheep systems)—Australia |
---|---|---|---|
Key parameters/model (Reference) | Key parameters/model (reference) | ||
Enteric methane | Methane (CH4) emitted by adult sheep | 0.0209 kg CH4/kg (DMI, MfE 2010) | |
Methane (CH4) emitted by young sheep (<1 year) | 0.0168 kg CH4/kg DMI (MfE 2010) | ||
Excreta methane | Kilograms CH4 emitted per kilogram faecal dry matter (DM) | 6.9 × 10−4 kg CH4/kg faecal DM (MfE 2010) | 5.4 × 10−5 kg CH4/kg faecal DM (DCCEE 2012) |
Excreta nitrous oxide | Kilograms of N2O-N emitted per kilogram of N due to urine deposited during grazing (EF3) | Urinary N—0.01 kg N2O-N/kg N in urine (MfE 2010) | Urinary N—0.004 kg N2O-N/kg N in urine (DCCEE 2012) |
Kilograms of N2O-N emitted per kilogram of N due to dung deposited during grazing (EF3) | Faecal N—0.0025 kg N2O-N/kg N in faeces (MfE 2010) | Faecal N—0.005 kg N2O-N/kg N in faeces (DCCEE 2012) | |
Nitrous oxide from stored manure | Kilograms of N2O-N emitted per kilogram of N due to manure storage | Manure N—0.02 kg N2O-N/kg N in stored manure (IPCC 2006) | n.a |
Excreta ammonia | Kilograms of NH3-N emitted per kilogram of N excreted (FRACGASM) | 0.1 kg NH3-N/kg N of excreted (MfE 2010) | 0.2 kg NH3-N/kg N of excreted (DCCEE 2012) |
Ammonia from stored manure | Kilograms of NH3-N emitted per kilogram of N in manure (FRACGASM) | 0.12 kg NH3-N/kg N in stored manure (IPCC 2006) | n.a |
Indirect nitrous oxide from ammonia losses | Kilograms of N2O-N emitted per kilogram of N due to atmospheric deposition of NH3 (EF4) | 0.01 kg N2O-N/kg NH3-N volatilised (IPCC 2006) | 0.01 kg N2O-N/kg NH3-N volatilised (DCCEE 2012) |
Excreta nitrate | Kilograms of NO3-N emitted per kilogram of N excreted or N fertiliser applied (FRACLEACH) | 0.07 kg NO3-N/kg N of excreted (Thomas et al. 2005) | ‘Drylands’ with the ratio of evapotranspiration to precipitation is outside the range where leaching is assumed to occur (i.e. Et/P <0.8 or Et/P > 1) (DCCEE 2012) |
Indirect nitrous oxide from nitrate losses | Kilograms of N2O-N emitted per kilogram of N due to leaching and runoff of NO3 (EF5) | 0.0075 kg N2O-N/kg NO3-N leached (IPCC 2006) | n.a (see above) |
2.3.2 Land occupation
2.3.3 Fossil fuel energy demand
2.4 Handling co-production
-
Clear subdivision of the system; or
-
System expansion (SE) (expanding the product system to include the additional functions related to the co-products to avoid allocation).
-
Allocation on the basis of physical or biological relationship; or
-
Allocation on some other basis, most commonly economic (market) value.
2.4.1 Methods for conducting biophysical allocation
2.4.2 Methods for conducting protein mass and economic allocation
CS 1 | CS 2 | CS 3 | CS 4 | ||
---|---|---|---|---|---|
Protein mass factors | |||||
Protein content of greasy woola
| 70 % | 66.6 % | 57.1 % | 57.1 % | |
Protein content of LW | 18.0 % | 18.0 % | 18.0 % | 18.0 % | |
Economic factors | |||||
Wool valueb
| £ or $/kg greasy | 1.09 | 2.76 | 6.80 | 9.80 |
LW valueb (average of all sales over ≥2 year period) | £ or $/kg LW | 1.56 | 1.98 | 1.63 | 1.57 |
2.4.3 Methods for conducting system expansion
3 Results
3.1 Partitioning of DPLS based on animal function and allocation methods
CS 1 (%) | CS 2 (%) | CS 3 (%) | CS 4 (%) | |
---|---|---|---|---|
Maintenance—flock (excluding lambs sold for slaughter) | 54.7 | 54.1 | 42.5 | 55.0 |
Maintenance—lambs sold for slaughter | 14.3 | 6.0 a
| 12.8 | 11.3 |
Wool | 7.0 | 17.3 | 22.2 | 15.1 |
Conceptus | 2.6 | 2.7 | 3.5 | 2.9 |
LW gain | 21.4 | 19.9 | 19.0 | 15.7 |
Total | 100.0 | 100.0 | 100.0 | 100.0 |
Utilised Digestible Proteinb
| 31.0 | 39.9 | 44.7 | 33.7 |
3.2 Impact of choice of method for handling co-products on greenhouse gas emissions
Allocation method | CS 1 (%) | CS 2 (%) | CS 3 (%) | CS 4 (%) |
---|---|---|---|---|
BA based on the proportion of utilised protein for wool and meat | ||||
Allocation factor for wool)—BA 1 | 22 | 43 | 50 | 45 |
Allocation factor for meat)—BA 1 | 78 | 57 | 50 | 55 |
BA based on allocation to meat of the maintenance requirements for lamb, LW gain and a proportion of flock maintenance | ||||
Allocation factor for wool)—BA 2 | 15 | 38 | 39 | 34 |
Allocation factor for meat)—BA 2 | 85 | 62 | 61 | 66 |
BA based on all maintenance requirements to sheep meat and direct protein requirements to wool only | ||||
Allocation factor for wool)—BA 3 | 7 | 17 | 22 | 15 |
Allocation factor for meat)—BA 3 | 93 | 83 | 78 | 85 |
Allocation based on protein mass | ||||
Allocation factor for wool | 19 | 39 | 40 | 35 |
Allocation factor for meat | 81 | 61 | 60 | 65 |
EA | ||||
Allocation factor for wool | 4 | 19 | 47 | 52 |
Allocation factor for meat | 96 | 81 | 53 | 48 |
3.3 Fossil fuel energy
3.4 Land occupation
CS 1 | CS 2 | CS 3 | CS 4 | |
---|---|---|---|---|
Cultivated land (m2 year/kg greasy wool) | ||||
BA 1 | 2.40 | 0.87 | 0.04 | 7.31 |
BA 2 | 1.64 | 0.76 | 0.03 | 5.68 |
BA 3 | 0.74 | 0.35 | 0.01 | 3.27 |
PMA | 1.87 | 0.78 | 0.03 | 5.92 |
EA | 0.43 | 0.39 | 0.05 | 6.91 |
SE - alt. sheep meat | n.a a
| n.a a
| 0.04 | 13.81 |
SE - beef | n.d b
| 0.16 | 0.03 | 7.31 |
CS 1 | CS 2 | CS 3 | CS 4 | |
---|---|---|---|---|
Cultivated land (m2 year/kg LW) | ||||
BA 1 | 0.497 | 0.195 | 0.010 | 1.276 |
BA 2 | 0.543 | 0.215 | 0.012 | 1.557 |
BA 3 | 0.597 | 0.285 | 0.016 | 1.972 |
PMA | 0.520 | 0.211 | 0.012 | 1.515 |
EA | 0.58 | 0.237 | 0.007 | 1.147 |