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Beyond the Bale : Jun - July 08
By Gio Braidotti T he project aim was simple: take pasture-based 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 detrimental effects on fleece weight or physical traits. Called T13 (towards 13 microns), the project set out to test long-standing assumptions on the degree of genetic linkage between commercially valuable wool traits. To pull the project off, CSIRO’s Dr Ian Purvis formed a consortium with six commercial stud breeders willing to put industry assumptions to the test. With Phase I now completed, the T13 consortium achieved average fibre diameter reductions of 0.3 micron per year during the seven-year project, without altering the look of the animals or staple strength. “It was a unique achievement in two ways,” Dr Purvis says. “It demonstrated that entire flocks can go finer than thought possible. “But additionally, having commercial breeders in the project meant that the research outcomes were embedded and automatically delivered to the wider stud breeding and wool-growing community.” From its inception, T13 was structured to run on a commercial basis. That requirement saw CSIRO registering as a Merino stud and the team sell wool under the T13 brand following shearing of their 400-ewe flock at Chiswick, near Armidale, NSW. Additionally, six commercial stud breeders from Western Australia, Victoria and NSW were invited to join the project by buying into the T13 consortium. Their involvement saw a further six flocks test the breeding objective in different environmental zones. T13 operational manager Dr Jen Smith says that although the project used a custom selection index, a similarly weighted index is available through the Sheep Genetics suite of database and software services (the so- called ‘20 per cent plus staple strength’ index). “Selection was based on pedigree records and year by Dr Smith herself. In addition to being a registered woolclasser, she and her husband are ultrafine woolgrowers who run their flock along similar lines to T13, but with greater emphasis on style traits, such as crimp and colour. Her flock has achieved similar rates of gain to the T13 nucleus flock. “A commitment to sticking to the breeding objective is what makes it possible, and with that comes a requirement for precise pedigree and production data recording,” Dr Smith says. Interestingly, the T13 flock that ran on basalt soils and improved pastures coincided with widespread drought conditions, which strained pasture conditions and made some supplementary feeding necessary. That substantial progress was nonetheless achieved stresses the genetic basis of the observed changes on wool diameter. That is, the team is confident that the T13 animals are genetically predisposed to produce ultrafine wool and can do so under a range of environmental conditions. Since dissolving the consortium, CSIRO has retained its flock for research purposes. The consortium members have either maintained a separate ultrafine line on their properties or fully integrated the T13 regime. As a registered Merino stud, CSIRO makes T13 semen, but not rams, available commercially. However, T13 rams are available through some consortium participants. In all, Dr Smith is well pleased with the project: “I think we have proven pretty well that you can have fine animals with good fleece weight without sacrificing style, staple strength or conformation characteristics.” ú More information: Dr Jen Smith, firstname.lastname@example.org 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 GenetICS BeyonD the Bale Dr Jen Smith with the t13 wool broker at the sale lots at newcastle, nSW. t13 – ‘towards 13 microns’ – ewes and hoggets involved in a study of grazing management effects on staple strength. CSIRO’s Dr Ian Purvis (far right) with t13 consortium members (from left) Alistair Lade of ‘Glenrannoch’ (Victoria), Grant nivison of ‘Yalgoo’ (nSW), Peter Mcneill of ‘europambela’ (nSW), Barry Walker of ‘Ledgerton’ (nSW), Hugh nivison of ‘Mirani’ (nSW) and Roland Ritson of ‘Grindon’ (WA). Bales of t13 wool. performance measurements, with fibre diameter, fleece weight and a whole suite of other characteristics recorded 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.” At the outset, the ewes screened into the starting T13 flock measured between 17.5 and 18 microns. To genetically link the participating flocks on different properties, consortium members used at least one common sire each year. The strategic inclusion of a few outside sires – including some from consortium members – saw the flock genetically linked to the national Merino database. After seven years of consistently applying the T13 selection index, flock average fibre diameter was reduced to about 15 microns for ewes and 14 microns and lower in hoggets. A small increase in staple strength was also observed and annual classing detected no detrimental effects on style. In every year of the project, T13 wool from the CSIRO flock was sold as a commercial brand. Consortium members had the option to contribute wool from their own T13 flocks. However, prices fetched fluctuated considerably due to market volatility. The best prices were achieved in 2006 when the average fleece value of hoggets was $240 per head. In that year the top bales of T13 wool sold for $375 and $345 per kilo. In 2007, the average fleece value was $143 a head. Over the past two years of the project, T13 sold five bales of hogget wool testing between 13.5 and 14.2 microns for more than $100 a kilo. “There was a strong belief in the industry that losses in fleece weight and style – the primary determinants of price – accompany reductions in wool diameter,” Dr Purvis says. “T13 showed that the existing micron dogma is not true. Given the right weighting between traits during selective breeding, you can reduce wool diameter with no adverse effects on quality.” Indeed, CSIRO’s sheep flock and wool were classed each PHOtOS: CSIRO
Jun - Jul 08 Supplement
Aug - Sep 08