Understanding MERINOSELECT ASBVs
Rams with a higher greasy fleece weight (GFWT) will produce progeny that cut more wool. A ram with an ASBV of 20% will produce progeny that cut 10% more wool than the progeny of a ram with an ASBV of 0. 
Animals with lower fibre diameter coefficient of variation (FDCV) ASBVs will genetically have a lower variation in fibre diameter. A higher CV% is often associated with lower staple strength. 
Animals with more positive staple strength (SS) ASBVs will, on average, have genetically stronger wool. This ram will, on average, sire progeny with 7.5 N/Kt stronger wool than an average sire. 
Rams with a more positive ASBV for eye muscle depth (EMD) produce lambs that have a higher lean meat yield. A ram with an ASBV of 1.0 will breed lambs with 0.5mm more EMD than a ram with an ASBV of 0. 
Worm egg count (WEC) ASBVs estimate an animal’s genetic potential for worm burden. More negative FEC ASBVs are desirable. This ram will, on average, sire progeny that will have 10% fewer eggs/gram than a ram with an ASBV of 0. 










WT (kg) 
GFWT (%) 
FD (μm) 
FDCV (%) 
SS (N/Kt) 
SL (mm) 
EMD (mm) 
NLW (%) 
WEC (%) 
INDEX 
4.0 65* 
20 68 
0.80 75 
1.24 70 
15 53 
10 56 
1.0 58 
10 35 
20 45 
138.6 










Animals with a more positive ASBV for weight (WT) will produce lambs that grow faster and therefore reach target weights in a shorter period of time. 
More negative fibre diameter (FD) ASBVs are generally desirable. A ram that has an ASBV of –0.8 will produce progeny that are genetically 0.4 microns finer than a ram with an ASBV of 0. 
Animals with more positive staple length (SL) ASBVs will, on average, have greater genetic potential for longer fibre length. This ram will sire progeny that grow, on average, 5mm longer wool than progeny of a ram with a 0 ASBV for SL. 
Rams with a more positive number of lambs weaned (NLW) ASBV will sire daughters that wean a higher percentage of lambs. A ram with an ASBV of 10 will sire daughters who on average will wean 5% more lambs than daughters of a ram with an ASBV of 0. 
An index is a guide to the value of a ram for a particular market. Rams with higher indexes will produce sheep that are more suited to that particular breeding objective. 
Note: A useful rule of thumb for converting ram ASBVs into sheep and wool production differences is to simply halve the ASBV (as rams contribute half the genetics of the lamb). * Accuracy: published as a percentage, is a reflection of the amount of effective information that is available to calculate the ASBV. All ASBVs are now published with accuracies. The higher the percentage, the closer the ASBV is to the true breeding value of the animal. An ASBV of 0 is the average of the 1990 drop. Breeding values without accuracies are Flock Breeding Values (FBVs) and can only be compared within flock.
Understanding LAMBPLAN ASBVs
Rams with lower ASBVs for birth weight (BWT) produce lambs with lower birth weight. Both low (lamb survival) and high (lambing difficulties) birth weights should be avoided. 
Rams with more positive ASBVs for post weaning weight (PWWT) produce lambs that grow quicker and reach target weights in a shorter time. This ram will produce lambs that are, on average, 3kg heavier at post weaning age (7.5 months) than a ram with an ASBV of 0. 
Worm egg count (WEC) ASBVs estimate an animals genetic potential for worm burden. More negative WEC ASBVs are desirable. This ram will, on average, sire progeny that will have 5% fewer eggs/gram than a ram with an ASBV of 0. 







BWT (kg) 
WWT (kg) 
PWWT (kg) 
PFAT (mm) 
PEMD (mm) 
WEC (%) 
INDEX 
0.3 43* 
4 63 
6.0 71 
1.5 59 
1.0 69 
10 37 
170 







Rams with a more positive ASBV for weaning weight (WWT) will, on average, produce lambs that grow quicker to weaning. This ram will produce lambs that are 2kg heavier than a ram with a 0 ASBV for WWT. 
Rams with a more negative ASBV for fat will produce lambs that are leaner, at the same weight. This ram will produce lambs that are, on average, 0.75mm leaner at the GR site when compared to a ram with a FAT ASBV of 0. 
Rams with more positive ASBVs for eye muscle depth (EMD) produce lambs that have more muscle, independent of weight, and a higher lean meat yield. This ram will produce lambs that have, on average, a 0.5mm deeper eye muscle than a ram with a 0 EMD ASBV. 
An index is a guide to the value of a ram for a particular market. Rams with higher indexes will produce lambs that are more suited to that particular market target. It is important to understand what market the index applies to before using an index. 
Note: A useful rule of thumb for converting ram ASBVs into lamb production differences is to simply halve the ASBV (as rams contribute half the genetics of the lamb). * Accuracy, published as a percentage, is a reflection of the amount of effective information that is available to calculate the ASBV. All ASBVs are now published with accuracies. The higher the percentage, the closer the ASBV is to the true breeding value of the animal. An ASBV of 0 is the average of the 1990 drop. Breeding values without accuracies are Flock Breeding Values (FBVs) and can only be compared within flock.
Understanding LAMBPLAN Maternal ASBVs
Weaning weight (WWT) ASBVs estimate the genetic difference between animals in liveweight at 100 days of age. This ram will produce lambs that are, on average, 0.4kg heavier than a ram with a 0 ASBV for WWT. 
Rams with more positive ASBVs for post weaning weight (PWWT) produce lambs that grow quicker and reach target weights in a shorter time. This ram will produce lambs that are, on average, 1.25kg heavier than a ram with a 0 ASBV for PWWT. 
Rams with more positive ASBVs for eye muscle depth (EMD) produce lambs that have a higher lean meat yield. This ram will produce lambs that have a 0.2mm deeper eye muscle than a ram with a 0 EMD ASBV. 
Rams with a higher greasy fleece weight (GFWT) ASBV will produce progeny that cut more wool. This ram will produce progeny that, on average, cut 2.5% more wool than a ram with an ASBV of 0. 
Worm egg count (WEC) ASBVs estimate an animals genetic potential for worm burden. More negative WEC ASBVs are desirable. This ram will, on average, sire progeny that will have 5% fewer eggs/gram than a ram with an ASBV of 0. 










WWT (kg) 
MWWT (kg) 
PWWT (kg) 
FAT (mm) 
EMD (mm) 
NLW (%) 
GFWT (%) 
SC (cm) 
WEC (%) 
INDEX 
0.8 51* 
1.0 53 
2.5 61 
0.4 45 
0.4 38 
4 33 
5 37 
0.6 44 
10 37 
105.6 










Rams with more positive ASBVs for maternal weaning weight (MWWT) will produce daughters which will wean heavier lambs. This ASBV reflects a combination of the daughter’s ability to milk and provide a better maternal environment. 
Rams with a more negative ASBV for fat produce lambs that are leaner, at the same weight. This ram will produce lambs that are 0.2mm leaner at the GR site when compared to a ram with a FAT ASBV of 0. 
Rams with a more positive number of lambs weaned (NLW) ASBV will sire daughters that wean a higher percentage of lambs. This ram with an ASBV of 4 will sire daughters which, on average, will wean 2% more lambs. 
Rams with higher scrotal circumference (SC) ASBVs will sire daughters that are, on average, more fertile. 
An index is a guide to the value of a ram for a particular market. Rams with higher indexes will produce lambs that are more suited to that particular market target. In many cases the indexes used for maternal breeds are in $ terms. 
Note: A useful rule of thumb for converting ram ASBVs into lamb production differences is to simply halve the ASBV (as rams contribute half the genetics of the lamb). * Accuracy: published as a percentage, is a reflection of the amount of effective information that is available to calculate the ASBV. All ASBVs are now published with accuracies. The higher the percentage, the closer the ASBV is to the true breeding value of the animal. An ASBV of 0 is the average of the 1990 drop. Breeding values without accuracies are Flock Breeding Values (FBVs) and can only be compared within flock. 