ASBVS & INDEXES EXPLAINED

Australian Sheep Breeding Values (ASBVs)

ASBVs are the genetic values of the various traits:

Birth Weight (Bwt)

All lambs are weighed and identified at birth. Big heavy lambs have a higher ASBV. BWT ASBVs above 0.3 have an increasing risk of slow lambings with stillbirths or brain damaged non surviving lambs. Our birth weight ASBVs for White Suffolks are consistently below 0.3 and for Poll Dorsets below 0.35. Our rams get more live lambs with easier ewe lambings.

Weaning Weight (Wwt)

All weaners are weighed, adjusted for singles, twins or triplets and given a growth ASBV.

Post Weaning Weight (Pwt)

At 200 days all lambs are weighed by an independent operator (Trevor Pearce) and a growth ASBV is calculated. Good growth rates with higher growth ASBV figures are much more profitable than slow growth rates with lower growth ASBV figures.

Yearling Weight (Ywt)

Growth ASBV at yearling age. With the change in teeth rules and the strong heavy lamb market the yearling ASBV has assumed more importance.

Post Weaning Fat (Pfat)

At 200 days all lambs are independently assessed by ultrasound and a fat EBV is calculated. For rams over Merino ewes an ideal fat ASBV is -0.5 to 0 or even positive. For rams over first cross ewes a leaner fat ASBV of -0.5 to -1 is more desirable. The desirable fat ASBVs may change with the introduction of abattoir DEXA technology, IMF measurement and associated price grids.

Post Weaning Eye Muscle Depth (Pemd)

At 200 days all lambs are independently assessed by ultrasound for loin eye muscle size and a muscle ASBV is calculated. Our sheep are well above the terminal average for muscling (Pemd). Abattoir DEXA technology emphasising carcase yield will highlight the importance of Pemd. Price grids may be based on carcase yield.

Post Weaning Faecal Egg Count (Pwec)

We collect faeces from every lamb for worm egg counts. Resistance to worms is inherited. The greater the minus figure the more resistance to worms the lamb has. We will continue to increase the worm resistance in our flock so the rams our clients will produce lambs that need less drenching.


 

Indexes

Lamb eating quality is deteriorating under the present genetic programs.
As a consequence, the industry has proactively designed measurements and indexes to maintain or improve eating quality:

Eating Quality (EQ)

Measured by blood test genomics mostly on the stud sires. A measure of the progeny’s potential eating quality.

Lamb Eating Quality (LEQ)

A combination index of the performance traits and eating quality designed to improve eating quality.

Total Carcase Performance (TCP)

A combination index of the performance traits and eating quality designed to maintain current eating quality.

Carcase Plus (C+)

A combination of the performance traits. Growth 65%, Fat 5% and EMD 30%. This index will be phased out over the next 12 months.