The undeniable benefit of ASBVs

18 February 2016

Lynley Anderson has followed in father Alan’s footsteps by embracing Australian Sheep Breeding Values (ASBVs) to determine an animal’s breeding value, based on pedigree and performance recordings. Alan was a pioneer of objective measurement in the 1960s, selecting rams based on clean fleece weight, fibre diameter and body weight, at a time when selection by visual assessment was the norm.

It's this long term commitment which Lynley believes will stand the enterprise in good stead to capture some of the benefits to be had from the growing demand for sheep out of Western Australia.

The Anderson's breeding objective is to produce robust, productive, low maintenance and fertile sheep. It starts with a nucleus flock of 450-500 Merino ewes and 120 Poll Dorset ewes.

While the Andersons found it difficult to quantify the financial gain of using ASBVs, Lynley said the benefit was undeniable.

“As a result, we’re running more stock, our lambing percentage has increased, we rarely drench and sheep maintain condition much more easily,” Lynley said.

Here is how the Andersons do it:


When Lynley joined the enterprise in the early 2000s, she was keen to take the sheep breeding to the next level. Despite the advances in key traits across their flock, the Andersons became concerned their selection strategy was “discounting” the potential of progeny from maiden ewes and twin bearers because they were lighter and cut less.

In 2002 the Andersons jumped at the chance to contribute to a pilot project for Sheep Genetics in the development of genetic breeding values.

“We could see great advantages in using genetic information to select animals because it removed the environmental influences on an animal’s appearance and its objective measurements,” Lynley said.

“We would be able to select the best rams regardless of the circumstances of their birth or upbringing.

“It was also a great opportunity to be able to breed for other traits like worm resistance, fast early growth and a meatier carcase which would enable us to turn off our wether lambs earlier.”


Lambs are tagged at birth in order to record their pedigree, birthweight, birth date and whether they are born a single or twins.

More than 50 visual and objective traits are measured and recorded for each animal from birth to hogget age to refine selection and provide accurate ASBVs for each sheep.

Objective measurements include clean fleece weight, fibre diameter, coefficient of fibre diameter, comfort factor, staple strength, worm egg count, eye muscle depth, carcass fat, birth weight and growth rates.

The visual traits assessed include body and breech wrinkle, wool colour, face cover, dags and temperament.

Of the meat traits, from 2003 to 2013, the average yearling weight has improved by 4kg and eye muscle depth has improved by 5mm, making the flock genetically more muscular and robust.

The average dual purpose index value of the flock is now 170 units, which is nearly 32 index points higher than the Merino ram breeding industry average, and about 34 index points higher than it was 10 years ago.

Low maintenance

The Andersons decided early on to focus on producing low maintenance sheep and started selecting for low faecal worm egg counts.

“It was clear that the effectiveness of drenches was fast declining and that any new drenches were going to be expensive so we wanted to do away with drenching altogether,” Lynley said. said.

To assist the process, the Andersons sourced semen from the Department of Agriculture and Food’s Rylington Merino Flock, which was dedicated to breeding sheep with resistance to worms.

The Andersons now have some of the most worm resistant sheep in the country, with many ranking in the top 1% in the MERINOSELECT database for this trait. 

The Andersons haven’t drenched their adult sheep for six years and only about 10% of weaners now require a drench.

Selecting for worm resistance is one trait Ms Anderson does not compromise on.

“An ASBV of -50 is my benchmark,” she said.

“When selecting rams there is always a compromise, as there is no such thing as a perfect ram, however, I won’t compromise on the worm egg count as it can limit the overall performance of the animal.”

More information

Lynley Anderson E:

 Sheep Genetics and MERINOSELECT

Read Module 9: Gain from Genetics from

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