Tool 3.3 Fat scoring lambs and sheep
Tool 3.3 Fat scoring lambs and sheep
Fat score (FS) is used for assessing live animals for slaughter.
GR measurement site
Scores are based on the tissue thickness (both fat and lean tissue) at the GR site. The GR measurement site is 110 mm from the carcase midline over the 12th rib. This site is used as a reference point because it is easy to measure on both the live animal (by manual palpation) and the hot carcase, and provides a good indication of the overall fatness and yield of the whole carcase.
On the slaughter floor, GR is usually measured with a ‘cut and measure’ knife or AUS-MEAT probe.
For MSA sheepmeat processing, the fat score is also determined on the depth of tissue at the GR site.
Fat scoring explained
The table describes the fat score, the coverage of tissue at the GR site and what you will feel over the long ribs during fat scoring. To achieve a reliable score, have the sheep or lamb standing in a race or on liveweight scales. The scorer must work fingers through the wool to skin level before feeling for fat cover over the rib bones.
Fat scoring guide
|
Fat Score |
1 |
2 |
3 |
4 |
5 |
|
GR tissue |
0 to 5 mm |
6 to 10 mm |
11 to 15 mm |
16 to 20 mm |
20 mm and over |
|
Feel at the |
Individual ribs felt easily. Cannot feel any tissue over |
Individual ribs easily felt but some tissue |
Individual ribs can still be felt. |
Can only just feel ribs. |
Ribs cannot be felt. |
Locating the GR site on the live animal and the carcase
Source: MLA
Recording the score
Randomly score 25-50 sheep from the middle of the mob. Record the fat score of each sheep with an X on the chart. The middle score of the distribution is close to the average.
In this example with 25 sheep, the median value is 3.0 but by using the chart you can see the average is just less than 3.0.
Download a blank Fat score recording sheet (52 KB)
Fat score and dressing percentage
Higher fat score animals have a higher dressing percentage, as shown below.
Dressing percentages related to fat score
|
|
Lambs |
Sheep |
||
|
Fat score |
Unweaned |
Weaned |
Wethers |
Ewes |
|
1 |
43% |
41% |
39% |
38% |
|
2 |
45% |
43% |
41% |
40% |
|
3 |
47% |
45% |
43% |
42% |
|
4 |
49% |
47% |
45% |
44% |
|
5 |
51% |
49% |
47% |
46% |
Source: MLA Live assessment yard book – sheep and lamb, adapted by AWI and MLA
Time off feed
When sheep and lambs are held off feed prior to sale or assessment, add the following to the dressing percentage figures above:
|
Time off feed |
% added to dressing percentage |
|
0-3 hours |
0 |
|
4-5 hours |
+1% |
|
6-8 hours |
+2% |
|
9-12 hours |
+2-3% |
|
13-24 hours |
+3.5-4.5% |
Source: MLA Live assessment yard book – sheep and lamb, adapted by AWI and MLA
