VARIATION in wool quality often shows up between differing rainfall zones, and now one Central West sheep and wool producer is having a crack at discovering why.
While sheep breeders have largely dealt with this by knowing the right "type" and selecting from studs known to perform in a particular climate, Mark Mortimer wants to take it a step further.
He wants to discover which aspects of "nourishment" - a term used to describe the wax and suint in wool - impact wool quality, including colour and character, plus whether it's possible to select sheep with less nourishment which maintain high quality wool regardless of their environment.
Mr Mortimer, "Devondale", Tullamore, is the Centre Plus Merino group's geneticist, a performance breeding group which he leads with his father Robert.
He has taken on this challenge after seeing variances in colour in a client's flock when moved from Tullamore to the Central Table- lands.
If factors of nourishment are responsible, he believes he will be able to develop a method of selection for wools which perform uniformly across different rainfall zones, while also increasing yield.
One aspect he believes is at play is the tendency of suint, at the right moisture levels, to act like a detergent and wash the wax from the wool, allowing colouring in higher rainfall environments and exposing the fibre to dust and other elements that can impact crimping, alignment and bundling.
The catalyst for the study was a Centre Plus member's flock which had grown six months of white wool at Tullamore, then grew six months of creamy wool after moving to a new property between Mudgee and Lake Burrendong.
"You could see the line in the fleece," Mark Mortimer said.
He kicked off his project when scanning the Centre Plus nucleus flock at "Devondale" in May this year by drafting 1200 ewes into three groups, including dark tip, light tip and the rest in the middle.
"Sub-sets drafted were 44 ewes with really dark tip and 189 with really light tip," he said.
Mr Mortimer has also been studying pedigrees and production records of the main flock of 1200 ewes since the member flagged his observation.
Each year the Centre Plus ewes are side sampled, not just for fibre diameter, but also for measuring yield and clean fleece weight.
The average greasy fleece weight Australian sheep breeding value (ASBV) for the light tipped group was 15.3pc and the greasy fleece weight figure for the dark tipped ewes was 17.3pc - 2pc higher.
However, the average clean fleece weight figure for the light tipped group was 14pc, while the clean fleece weight for the dark tipped ewes was 15pc, almost identical.
"This showed a genetic link for the dark tipped ewes back to their yield - dark tip is displaying in more grease and lower yield," he said.
However, yield didn't affect the monetary gain per kilogram.
"So the economist in me says you need more of a reason to change yield," he said.
This is where nourishment and its potential impacts on colour came into play.
Mr Mortimer said if he looked at the Merino Production Plus index of the dark tipped and light tipped groups of ewes, one was 163 and the other 162.4.
"Which in money terms means the fleece groups are identical, so neither is making more money than the other," he said.
"But genetically, the dark tipped ewes (appear to have) fractionally more colour in the wool than the light tipped ewes."
And colour can bring a discount.
Mr Mortimer said in Tullamore's dry environment the darker tipped ewes' wool had better style (crimp, bundles and alignment).
"It's a nice visual style, but when dark tipped ewes go to other environments they are possibly a lot more creamy," he said.
On the first run through the numbers Mr Mortimer said nourishment and dry environment had benefits in style and appearance, and showing lower levels of dust penetration.
While these well-nourished ewes performed well in the dry Tulla- more environment, he wanted to find a type that performed as well in terms of quality in wetter zones.
He is therefore seeking the exceptions among the nucleus flock which have less nourishment, but maintain quality, so when they go to wetter climates they are less likely to yellow.
In drier climates they would have a lighter tip and better yield.
"We are looking for wools that are not carrying a lot of grease, but are still well protected and have a nice structure."