The T13 project aimed to reduce Merino wool fibre diameter to 13 microns through selective breeding while avoiding negative impacts on other traits like fleece weight. Over seven years, the average fibre diameter of ewes in the T13 flock was reduced by 0.3 microns per year to around 15 microns, demonstrating fibre finer than previously thought possible. No detrimental effects on style or staple strength were observed. The involvement of commercial breeders helped validate the research for industry application and the ultrafine wool sold successfully.

1. 6
GENETICS
BEYOND THE BALE
PHOTOS: CSIRO
T13 – ‘towards 13 microns’ – ewes Bales of T13 wool.
and hoggets involved in a study of
grazing management effects on
staple strength.
Dr Jen Smith with the T13
wool broker at the sale lots at
Newcastle, NSW.
How low can fibre diameter go?
With the genetic data unequivocally saying it was possible, CSIRO’s Dr Ian Purvis set
out to prove that a correctly weighted selection index could take a Merino flock into the
ultrafine range, without adversely affecting production or conformation characteristics
CSIRO’s Dr Ian Purvis (far right) with T13 consortium
By Gio Braidotti performance measurements, with fibre diameter, fleece members (from left) Alistair Lade of ‘Glenrannoch’
(Victoria), Grant Nivison of ‘Yalgoo’ (NSW), Peter
he project aim was simple: take pasture-based weight and a whole suite of other characteristics recorded
T Merino flocks from across the country, apply a
breeding objective set to reduce fibre diameter to
13 microns, and then breed for ultrafine wool while avoiding
for every animal, every year,” Dr Smith says. “Records were
deposited in Sheep Genetics where the public can search the
animals from the T13 flock.”
McNeill of ‘Europambela’ (NSW), Barry Walker of
‘Ledgerton’ (NSW), Hugh Nivison of ‘Mirani’ (NSW)
and Roland Ritson of ‘Grindon’ (WA).
detrimental effects on fleece weight or physical traits. At the outset, the ewes screened into the starting T13 year by Dr Smith herself. In addition to being a registered
Called T13 (towards 13 microns), the project set out flock measured between 17.5 and 18 microns. To genetically woolclasser, she and her husband are ultrafine woolgrowers
to test long-standing assumptions on the degree of genetic link the participating flocks on different properties, who run their flock along similar lines to T13, but with
linkage between commercially valuable wool traits. To pull consortium members used at least one common sire each greater emphasis on style traits, such as crimp and colour.
the project off, CSIRO’s Dr Ian Purvis formed a consortium year. The strategic inclusion of a few outside sires – including Her flock has achieved similar rates of gain to the T13
with six commercial stud breeders willing to put industry some from consortium members – saw the flock genetically nucleus flock.
assumptions to the test. With Phase I now completed, the linked to the national Merino database. “A commitment to sticking to the breeding objective is
T13 consortium achieved average fibre diameter reductions After seven years of consistently applying the T13 what makes it possible, and with that comes a requirement
of 0.3 micron per year during the seven-year project, without selection index, flock average fibre diameter was reduced for precise pedigree and production data recording,”
altering the look of the animals or staple strength. to about 15 microns for ewes and 14 microns and lower in Dr Smith says.
“It was a unique achievement in two ways,” Dr Purvis hoggets. A small increase in staple strength was also observed Interestingly, the T13 flock that ran on basalt soils and
says. “It demonstrated that entire flocks can go finer than and annual classing detected no detrimental effects on style. improved pastures coincided with widespread drought
thought possible. In every year of the project, T13 wool from the CSIRO conditions, which strained pasture conditions and made
“But additionally, having commercial breeders in the flock was sold as a commercial brand. Consortium members some supplementary feeding necessary. That substantial
project meant that the research outcomes were embedded had the option to contribute wool from their own T13 progress was nonetheless achieved stresses the genetic basis
and automatically delivered to the wider stud breeding and flocks. However, prices fetched fluctuated considerably due of the observed changes on wool diameter. That is, the team
wool-growing community.” to market volatility. is confident that the T13 animals are genetically predisposed
From its inception, T13 was structured to run on a The best prices were achieved in 2006 when the average to produce ultrafine wool and can do so under a range of
commercial basis. That requirement saw CSIRO registering fleece value of hoggets was $240 per head. In that year the environmental conditions.
as a Merino stud and the team sell wool under the T13 top bales of T13 wool sold for $375 and $345 per kilo. In Since dissolving the consortium, CSIRO has retained
brand following shearing of their 400-ewe flock at Chiswick, 2007, the average fleece value was $143 a head. Over the its flock for research purposes. The consortium members
near Armidale, NSW. Additionally, six commercial stud past two years of the project, T13 sold five bales of hogget have either maintained a separate ultrafine line on their
breeders from Western Australia, Victoria and NSW wool testing between 13.5 and 14.2 microns for more than properties or fully integrated the T13 regime. As a registered
were invited to join the project by buying into the T13 $100 a kilo. Merino stud, CSIRO makes T13 semen, but not rams,
consortium. Their involvement saw a further six flocks test “There was a strong belief in the industry that losses in available commercially. However, T13 rams are available
the breeding objective in different environmental zones. fleece weight and style – the primary determinants of price through some consortium participants.
T13 operational manager Dr Jen Smith says that – accompany reductions in wool diameter,” Dr Purvis says. In all, Dr Smith is well pleased with the project: “I think
although the project used a custom selection index, a “T13 showed that the existing micron dogma is not true. we have proven pretty well that you can have fine animals
similarly weighted index is available through the Sheep Given the right weighting between traits during selective with good fleece weight without sacrificing style, staple
Genetics suite of database and software services (the so- breeding, you can reduce wool diameter with no adverse strength or conformation characteristics.” ú
called ‘20 per cent plus staple strength’ index). effects on quality.”
“Selection was based on pedigree records and Indeed, CSIRO’s sheep flock and wool were classed each More information: Dr Jen Smith, jen.smith@csiro.au