THE long-term use of Australian Sheep Breeding Values (ASBVs), combined with stringent visual assessment, is effectively matching rams to their breeding environment and bolstering productivity in Western Australian flocks.
WA ram breeding group, the Australian Merino Society (AMS) has moved its objective selection from an index based on raw measurements to the use of ASBVs, both in the stud itself and in the selection of rams for its commercial members.
The move has allowed the group to track the changes occurring in different traits from year to year and record progress accurately and without being distorted by seasonal influences.
"We have created our own customised ASBV index which reflects the economic importance of traits to us, called the AMS WP Index (WP stands for Wool Production)," AMS ram breeding member Ashley Hobbs said.
"With the help of the index we aim to increase fleece weight, yield, staple strength, carcase weight and number of lambs weaned, maintain fibre diameter and reduce susceptibility to worms."
Ashley and Lucille Hobbs run the Ingle Merino stud near Brookton, WA, which is one of two AMS studs providing rams to both AMS group members as well as commercial Merino producers.
AMS was established in 1967 by a group of like-minded WA breeders with the common goal of breeding sheep to maximise sheep profits per hectare.
All rams that go back into the stud are selected using the AMS WP index and, as a general rule, they must perform better than their sire in order to replace him.
As a result the use of young rams has contributed to a rapid increased in the rate of genetic gain through shortening the generation interval.
Industry leading sires from other studs are also used in regular artificial insemination (AI) programs, but visual appraisal is equally important as the ASBV numbers in selecting breeding stock, with the combination of tools being essential to achieving defined breeding goals.
"Obvious fleece and body conformation faults are culled and scrotal circumference is measured to assess serving capacity and reproductive potential," Mr Hobbs said.
"The sheep need to be able to operate in the environment that members use them - there's no point having a great indexing ram if he doesn't have the survivability and breaks down in the paddock."
Commercial members of the AMS ram breeding group are allocated rams based on the selection index. All AMS members, which includes the Hobbs' own 1300 ewe commercial flock, are given the chance once a year to put in their ram order.
One such member who has already benefitted from the genetic gains that AMS is making is Brett Whittington, who runs a cropping and sheep enterprise just down the road from the Hobbs'.
Before joining AMS as a member about eight years ago, rams in Mr Whittington's operation were purchased from a private stud.
"We were happy with the rams we were buying and the sheep we were breeding," he said.
"At the time we were just looking for something that might do a little better so we decided to try one of Ashley's rams.
"Twelve months later that ram we bought home was a standout in our ram mob, both he and his progeny had done so well and seemed really suited to our environment."
Since then Mr Whittington has only used AMS rams in his Merino breeding program and contributes some significant genetic gain to the switch.
"Our wool clip has reduced from 21.3 to 20 micron over that time and the wool is so much more consistent with more ending up in the top line," he said.
"Likewise, the sheep themselves are more uniform and there are a lot less culls."
The reduction in micron alone has delivered a permanent financial gain - based on the last 10 years of Australian Wool Exchange average prices, Mr Whittington could expect each ewe to cut an additional $1.25 worth of wool.
"I've also noticed the sheep are now consistently three-quarters of a condition score better than they used to be without any other changes to the management system," he said.
"The extra weight and fat the sheep carry may be one of the reasons why our lambing percentage has increased over the last few years."
Key results from using ASBVs:
Over a 10 year period, selecting rams using the customised Australian Merino Society (AMS) Wool Production ASBV Index, the Hobbs family aim to achieve:
- 0.5kg increase in clean fleece weight
- 20% improvement in number of lambs weaned
- 2kg increase in bodyweight and 5mm increase in eye muscle depth
Commercial producer Brett Whittington has also improved his flock's body score by 0.75 and reduced micron from 21.3 to 20 using the AMS WP ASBV index.
Read the full Hobbs family case study and obtain more information on the use of ASBVs and objective breeding tools at the Sheep CRC website, www.sheepcrc.org.au