Reference
ASBV glossary
Plain-English definitions of every Australian Sheep Breeding Value (ASBV) trait code we publish. Direction labelled "favourable" indicates whether higher or lower values are generally desirable.
Growth
- PWWTPost-Weaning WeightUnit: kg · Favourable: higher
- Genetic merit for live weight at around 7 months of age, after weaning. Higher ASBVs indicate progeny that grow faster between weaning and post-weaning weighing.
- YWTYearling WeightUnit: kg · Favourable: higher
- Genetic merit for live weight at around 12 months of age. Useful as a later-life indicator of growth potential.
Carcase
- YFATYearling FatUnit: mm · Favourable: depends on system
- Genetic merit for fat depth at the C-site, measured ultrasonically at around 12 months. Direction depends on system: fat cover supports survival and reproduction, excess fat reduces meat yield.
- YEMDYearling Eye Muscle DepthUnit: mm · Favourable: higher
- Genetic merit for the depth of the loin muscle, measured ultrasonically at around 12 months. Higher values predict more lean meat yield.
- CSCarcase StrengthUnit: index · Favourable: higher
- A combined carcase index incorporating weight, eye muscle depth, fat, and meat-quality traits. Higher values indicate stronger overall carcase performance.
- IMFIntramuscular FatUnit: % · Favourable: higher
- Genetic merit for marbling within the loin muscle. Higher IMF is associated with better eating quality (flavour and juiciness).
- SHRF5Shear Force 5 DaysUnit: kg · Favourable: lower
- Genetic merit for meat tenderness after five days of ageing, measured by mechanical shear force. Lower values predict more tender meat.
Wool
- YCFWYearling Clean Fleece WeightUnit: % · Favourable: higher
- Genetic merit for clean fleece weight at around 12 months, expressed as a percentage above or below the industry base. Higher values mean heavier-cutting sheep.
- YFDYearling Fibre DiameterUnit: µm · Favourable: lower
- Genetic merit for average wool fibre diameter at around 12 months. Lower micron is finer wool, generally higher value per kilogram with tradeoffs in fleece weight.
- YFDCVYearling Fibre Diameter CVUnit: % · Favourable: lower
- Genetic merit for variability in fibre diameter (coefficient of variation). Lower values indicate a more uniform fleece, which processes better and resists fibre breakage.
- YSLYearling Staple LengthUnit: mm · Favourable: higher
- Genetic merit for staple length at around 12 months. Higher values mean longer wool staples, generally more valuable for combing.
- LCOLLate Fleece ColourUnit: score · Favourable: lower
- Genetic merit for fleece colour at adult age, scored visually. Lower values indicate whiter, brighter wool, which is more valuable.
- LCHARLate CharacterUnit: score · Favourable: higher
- Genetic merit for fleece crimp definition and overall fleece character at adult age. Higher scores indicate a more clearly defined crimp pattern.
Health
- YFECYearling Faecal Egg CountUnit: % · Favourable: lower
- Genetic merit for resistance to internal parasites, measured as worm egg count in faeces at around 12 months. Lower values indicate sheep more resistant to worms, reducing drench reliance.
- EBWREarly Breech WrinkleUnit: score · Favourable: lower
- Genetic merit for skin wrinkle around the breech at weaning, scored 1 to 5. Lower scores mean smoother breech skin and reduced flystrike risk.
- EBCOVEarly Breech CoverUnit: score · Favourable: lower
- Genetic merit for the amount of wool around the breech at weaning, scored 1 to 5. Lower scores mean less wool cover, reducing flystrike risk and crutching cost.
- LDAGLate DagUnit: score · Favourable: lower
- Genetic merit for dag accumulation at adult age, scored 1 to 5. Lower scores indicate cleaner sheep that require less crutching.
- LFROTLate Fleece RotUnit: score · Favourable: lower
- Genetic merit for fleece rot susceptibility scored on adult animals. Lower values indicate sheep more resistant to fleece rot in wet conditions.
Reproduction
- WRWeaning RateUnit: % · Favourable: higher
- Genetic merit for the proportion of lambs weaned per ewe joined, combining fertility, fecundity, and lamb survival. Higher values indicate ewes more likely to wean a lamb.
- ERAEarly Reproductive AbilityUnit: index · Favourable: higher
- A composite ASBV summarising reproductive performance traits expressed at the first joining. Higher values indicate earlier and more reliable reproductive outcomes.
ASBV definitions sourced from Sheep Genetics. Direction guidance reflects the typical Australian commercial Merino objective. For more detail, see sheepgenetics.org.au.