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5-Animals: Shrink-proof sheep

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TITLE:  Shrink-proof sheep
SOURCE: CSIRO, Australia, Media Release, Ref 2003/72
DATE:   May 2, 2003

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Shrink-proof sheep

Shrinkage of woolen garments on 'wash-day' could soon be reduced
dramatically following the discovery that wool shrinkage (felting) is a
heritable trait that can be manipulated through selective sheep breeding.

Felting causes significant problems in the manufacture of knitted and
woven wool products - particularly fine wool garments - and is a major
factor in 50 per cent of wool consumers rating woolen garments difficult
to care for.

The finding that felting is a heritable trait - along with other wool
characteristics such as dust content - means sheep can be bred to produce
wool which is less prone to shrinkage.

"It is possible for wool growers to identify and select sheep which
naturally produce low-shrinkage wool," says CSIRO Livestock Industries'
Dr Tony Schlink.

In collaboration with Western Australian Department of Agriculture
geneticist Dr Johan Greeff, Dr Schlink processed over 2000 wool samples
from the Katanning Merino resource flocks for various wool fibre traits
and 'feltball density'.

"To perform the feltball density test, we put one gram of clean, hand-
carded wool in a container with water, then placed the container in a
front-loading tumble drier at 20 degrees for 30 minutes," Dr Schlink says.

"The samples come out as a nice round ball - the smaller the ball, the
greater the felting."

By using pedigree information and removing the effects of fibre diameter,
fibre curvature and yield, the wool's heritability for felting can be

"Altering the ability of wool to felt through conventional breeding may
make a considerable contribution to wool processing," Dr Schlink says.

Studies conducted with CSIRO Textile and Fibre have shown that knitted
fabric made from low-felting wool has reduced pilling and shrinkage. The
studies demonstrate that differences between low and high-felting wools
are preserved through the wool processing chain.

Low-felting wool also produced longer length and less entanglement during
the scouring process, resulting in fewer breakages during spinning.

Dr Schlink says a biological approach to reducing the felting capacity of
wool could also mean a reduction in the quantities of chemicals currently
applied to wool to prevent shrinkage.

"Breeding offers the potential to eventually produce wool that does not
need to be chemically treated to achieve desirable fabric
characteristics," Dr Schlink says.

In a separate study conducted with University of Western Australia
Honours student Melanie Ladyman, and supervised by Dr Schlink, the wool's
ability to hold dust was also found to be a highly heritable trait.

"Some sheep are more susceptible to dust content in their wool than
others," Dr Schlink says.

"As with felting, wool growers in areas where dust is a problem can breed
sheep with a stronger resistance to dust content."

More information:
Dr Tony Schlink, CSIRO Livestock Industries, 08 9333 662 or 08 9445 1727
Dr Johan Greef, Dept Agriculture WA, 08 9821 3215

Media assistance:
Margaret Puls, CSIRO Livestock Industries, 08 9333 6403, mobile: 0419 578 356

See also:

Mr Bill Stephens
Journalist CSIRO Media PO Box 225 Dickson ACT 2602 Phone: +61 2 6276 6152
Fax: +61 2 6276 6821 Email:

Ms Margaret Puls
Communications Officer CSIRO Livestock Industries Private Bag 5 Wembley
WA 6913 Australia Phone: +61 8 9333 6403 Fax: +61 8 9383 7688 Mobile:
0419 578 356 Email: