Tool 9.1 ASBV explanations and examples
ASBV explanations and examples
Sheep Genetics analyses and reports over 90 traits between the MERINOSELECT, DOHNE, LAMBPLAN Maternal and LAMBPLAN Terminal databases, which are reported as Australian Sheep Breeding Values (ASBVs).
ASBVs are a prediction of an animal’s genetic merit for a particular trait and an indication of how an animal’s progeny will perform based on the genes they will pass on. ASBVs are generated from the data, pedigree and genomic information collected by Sheep Genetics members to provide a prediction of genetic merit, accounting for heritability and correlations, as well as non-genetic factors (known environmental factors), to determine an animal’s genetic merit for a range of important traits.
ASBVs are comparable across flocks, though an ASBV may be different to the animal's actual performance, as actual performance is a combination of both genetic and environmental influences.
Most ASBVs are reported and displayed with the same units used to measure the trait. For example, the ASBV for fibre diameter (FD) is reported in microns, the ASBV for weight (WT) is reported in kilograms, and the ASBVs for traits that are measured in visual scores are reported using scores. Some traits, like clean fleece weight (CFW) and fibre diameter coefficient of variation (DCV) are provided as percentages.
There are ASBVs for many different traits that impact the performance and profitability of sheep enterprises. These include:
- reproduction
- growth
- carcase
- eating quality
- wool
- health and welfare.
Examples of traits from each of these categories follows, with an explanation of the trait, correlations and associated information.
Reproduction traits
|
Trait |
Reproduction trait group |
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|
Conception |
Scrotal Circumference |
Condition Score |
Litter Size |
Gestation Length |
Lambing Ease |
Ewe Rearing Ability |
Weaning Rate |
||||||||
|
ASBV trait code |
YCON |
CON |
PSC |
YSC |
CS |
YLS |
LS |
GL DIR |
GL DTR |
LE DIR |
LE DTR |
YERA |
ERA |
YWR |
WR |
|
Example ASBV |
0.32 |
0.09 |
6.38 |
4.96 |
0.67 |
0.26 |
0.41 |
0.62 |
-0.41 |
1.22 |
0.31 |
0.05 |
0.03 |
0.48 |
0.15 |
|
Example Acc (%) |
58 |
46 |
59 |
54 |
54 |
48 |
51 |
64 |
64 |
48 |
50 |
38 |
44 |
51 |
57 |
|
Example Av |
0.24 |
0.03 |
3.77 |
2.95 |
0.12 |
0.14 |
0.15 |
-0.2 |
-0.26 |
-1.29 |
-3 |
0.03 |
0.01 |
0.37 |
0.15 |
|
Age stages available |
Yearling |
Adult |
Post-weaning |
Yearling |
Adult |
Yearling |
Adult |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
N/A |
|
Definition |
The genetic difference between sires to produce daughters that in turn conceive more lambs. |
The genetic difference in scrotal circumference measured either at post-weaning or yearling. |
The condition of the ewe at joining. |
The genetic difference between rams to sire daughters who have larger litters. |
The difference between sires for the gestation length of their progeny. |
The difference between sires for the gestation length of their daughters’ subsequent pregnancies. |
The genetic difference between rams in the ease of their progeny to be born. |
The genetic difference between rams or the ease of their daughters during lambing. |
The genetic difference between animals for rearing ability |
The genetic difference between animals for the number of lambs weaned per ewe joined, as a yearling. |
The genetic difference between animals for the number of lambs weaned per ewe joined, as an adult. |
||||
|
Unit |
Number of lambs per ewe joined |
Centimetres (cm) |
Body condition score |
Number of lambs per ewe lambing |
Percentage (%) |
Percentage (%) |
Number of lambs per ewe lambing |
Number of lambs per ewe joined |
Number of lambs per ewe joined |
||||||
|
Favourable correlation |
Better lifetime reproductive success |
Improved reproductive rate |
Improved conception rates |
Better lifetime reproductive success |
N/A |
N/A |
Higher lamb survival |
N/A |
N/A |
||||||
|
Unfavourable correlation |
N/A |
N/A |
N/A |
Higher adult weights |
Lower muscle |
N/A |
N/A |
N/A |
N/A |
N/A |
|||||
Growth traits
|
|
Growth trait group |
||||
|
Trait |
Birth Liveweight |
Weaning Liveweight |
Post-weaning Liveweight |
Yearling Liveweight |
Adult Liveweight |
|
ASBV trait code |
BWT |
WWT |
PWT |
YWT |
AWT |
|
Example ASBV |
0.2 |
10.51 |
19.5 |
15.78 |
18 |
|
Example Acc (%) |
63 |
65 |
60 |
59 |
55 |
|
Example Av |
0.34 |
9.56 |
14.56 |
14.92 |
17.46 |
|
Age stages available |
Birth, weaning, post-weaning, yearling, hogget, adult |
||||
|
Definition |
The genetic difference in liveweight measured at birth. |
The genetic difference in liveweight measured at weaning. |
The genetic difference in liveweight measured at post weaning. |
The genetic difference in liveweight measured at yearling. |
The genetic difference in liveweight measured at adult |
|
Unit |
Kilograms (kg) |
Kilograms (kg) |
Kilograms (kg) |
Kilograms (kg) |
Kilograms (kg) |
|
Favourable correlation |
Higher lifetime growth |
Marketable at earlier ages, higher reproductive output, higher lean meat yield, higher fleece weight |
Marketable at earlier ages, higher reproductive output, higher lean meat yield, higher fleece weight |
Marketable at earlier ages, higher reproductive output, higher lean meat yield, higher fleece weight |
Marketable at earlier ages, higher reproductive output, higher lean meat yield, higher fleece weight |
|
Unfavourable correlation |
too low – lower lamb survival |
increase in adult weight, lamb birthweight increases, fibre diameter goes up |
increase in adult weight, lamb birthweight increases, fibre diameter goes up |
increase in adult weight, lamb birthweight increases, fibre diameter goes up |
increase in adult weight, lamb birthweight increases, fibre diameter goes up |
Carcase traits
|
|
Carcase trait group |
||
|
Trait |
Eye Muscle Depth |
Fat |
Carcase Weight |
|
ASBV trait code |
EMD |
FAT |
CWT |
|
Example ASBV |
3.32 |
0.14 |
6.02 |
|
Example Acc (%) |
64 |
64 |
59 |
|
Example Av |
1.87 |
-0.39 |
5.08 |
|
Age stages available |
Post-weaning, yearling, |
N/A |
|
|
Definition |
The genetic difference between animals for eye muscle depth at the C site. |
The genetic variation of fat depth at the C site. |
The genetic difference in weight measured on the carcase. |
|
Unit |
Millimetres (mm) |
Kilograms (kg) |
|
|
Favourable correlation |
Lean meat yield, dressing percentage, worm resistance |
Improved reproductive rate, CV of Fibre diameter goes down, intramuscular fat improves, eating quality improves |
Marketable at earlier ages, higher reproductive output, higher lean meat yield, higher fleece weight |
|
Unfavourable correlation |
Growth, eating quality |
Carcase fatness goes up and fleece weight goes down |
Increase in adult weight, birth weight increases, eating quality |
Eating quality traits
|
|
Eating quality trait group |
|||
|
Trait |
Lean Meat Yield |
Intramuscular Fat |
Shear Force |
Dressing Percentage |
|
ASBV trait code |
LMY |
IMF |
SHEARF5 |
DRESS |
|
Example ASBV |
4.37 |
-0.55 |
5.26 |
2.86 |
|
Example Acc (%) |
53 |
48 |
52 |
55 |
|
Example Av |
3.24 |
-0.46 |
2.42 |
2.12 |
|
Age stages available |
N/A |
N/A |
N/A |
N/A |
|
Definition |
The genetic difference between animals for the amount of lean meat yield derived from the carcase. |
The genetic difference between animals for the amount of intramuscular fat or marbling expressed in the meat. |
A measure of the force required to cut through the loin muscle after 5 days of aging, indicating tenderness. |
The genetic difference between animals for dressing percentage as measured at slaughter. |
|
Unit |
Percentage (%) |
Percentage (%) |
Newton-metre (nM) |
Percentage (%) |
|
Favourable correlation |
Growth increases, higher proportion of saleable meat |
Reduced birth weight, shear force decreases |
IMF increases |
Growth increases, increased lean meat yield |
|
Unfavourable correlation |
Intramuscular fat decreases, shear force increases and birthweight increases |
Growth decreases, carcase decreases and lean meat yield decreases |
Growth decreases, lean meat yield decreases, worm resistance decreases |
Intramuscular fat decreases, shear force increases, birthweight increases |
Wool traits
|
Trait |
Wool trait group |
|||||
|
Greasy Fleece Weight |
Clean Fleece Weight |
Fibre |
Staple Strength |
Fibre |
Staple |
|
|
ASBV trait code |
GFW |
CFW |
FD |
SS |
DCV |
SL |
|
Example ASBV |
24.23 |
11.38 |
-3.76 |
-4.61 |
0.13 |
3.84 |
|
Example Acc (%) |
70 |
66 |
82 |
56 |
72 |
62 |
|
Example Av |
14.06 |
16.67 |
-0.99 |
0.66 |
-0.87 |
8.13 |
|
Age stages available |
Post-weaning, yearling, hogget, adult |
|||||
|
Definition |
The genetic differences between animals for greasy fleece weight. |
The genetic difference a between animals for clean fleece weight. |
The genetic difference between animals for fibre diameter. |
The genetic difference between animals for staple strength. |
The genetic difference between animals for fibre diameter CV. |
The genetic difference between animals for staple length. |
|
Unit |
Percentage (%) |
Percentage (%) |
Micron (µm) |
Newtons per kilotex (N/kt) |
Percentage (%) |
Millimetres (mm) |
|
Favourable correlation |
Body weight, growth and improved staple length |
Body weight, growth and improved staple length |
NA |
Higher fleece weight, lower fibre diameter CV |
Resistance to worms, staple strength, reduced fleece rot, less body strike |
Increased fleece weight, higher growth, less fleece rot |
|
Unfavourable correlation |
Higher fibre diameter, increased wrinkle, reduced fat, reduced reproduction |
Higher fibre diameter, increased wrinkle, reduced fat, reduced reproduction |
Lower fleece weight, lower body weight, reduced staple strength, reduced staple length |
Higher fibre diameter |
Lower fleece weight |
Reduced reproduction, higher fibre diameter |
Health and welfare traits
|
Trait |
Health and welfare trait group |
||||
|
|
Breech Wrinkle |
Dag |
Breech Cover |
Worm Egg Count |
|
|
ASBV trait code |
BWR |
DAG |
BCOV |
WEC |
|
|
Example ASBV |
-2.11 |
-0.19 |
-0.47 |
-53.13 |
|
|
Example Acc (%) |
64 |
66 |
69 |
51 |
|
|
Example Av |
-0.21 |
-0.1 |
-0.1 |
-15.37 |
|
|
Age stages available |
Early |
Late |
Early |
Weaning, post-weaning, yearling, hogget |
|
|
Definition |
The genetic difference between animals for the amount of wrinkle in the breech area. |
The genetic difference between animals for the amount of dag in the breech area. |
Genetic difference between animals for the amount of bare cover in the breech area. |
The genetic difference between animals for worm egg count measured |
|
|
Unit |
Score |
Percentage (%) |
|
||
|
Favourable correlation |
Reduced fly strike susceptibility, higher staple length, improved reproduction |
Reduced fly strike susceptibility, reduced crutching, more saleable wool, less costs due to wool washing etc. |
Reduced flystrike |
Higher muscling, higher staple strength |
|
|
Unfavourable correlation |
Lower fleece weight |
N/A |
N/A |
N/A |
|
