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Beyond the Bale : Feb 07 - Mar 07 Supplement
GENETICS opted to mules all ewe lambs to minimise breech stain and leave the wether portion untreated. This will allow the organisers to assess what impact the 13 different sires in the trial had on the development of breech bareness before the wethers are sold as one-year-olds.The progeny will also be measured for their productive characteristics such as fleece weight and micron. "No one really has a handle on the link between selecting for a bare breech and productivity, so hopefully these trials will give us some results," Mr Toland says. "The most important thing for woolgrowers is to have productive sheep and there is a real concern that selecting for bareness will drop wool productivity. "If sheep with bare breeches Breech score guide available A pocket guide on visual breech scores is available free from AWI to help woolgrowers identify and breed sheep that are less susceptible to breech flystrike. The Visual Breech Scores guide, the first of its kind in Australia, has been developed by AWI as part of its support for research into alternatives to conventional mulesing. The new guide focuses on breech characteristics known to reduce susceptibility to breech flystrike -- breech wrinkle, bare breech area and dag score. The new scoring system is being used in AWI- funded research flocks to determine the heritability of these traits and measure their impact, if any, on important production traits such as fleece weight, fibre diameter and body weight. The fit-in-your-back- pocket guide includes full- colour photographs of the traits and corresponding scores, and is printed on durable, weatherproof paper to ensure its robustness.The guide has been developed in consultation with the nation's leading sheep researchers and woolgrowers and is designed for day-to-day use on-farm. The Visual Breech Scores have also been developed with the aim of generating sufficient data to help Sheep Genetics Australia develop Australian Sheep Breeding Values (ASBVs) for each breech trait. More information: copies of the Visual Breech Scores guide can be ordered via the AWI Helpline 1800 070 099 or by visiting www.wool.com.au Breeding bare-breech sheep is another industry initiative to beat the blowfly. breech area is defined as the area around the anus and vulva, with the goal of a bare breech being to naturally mimic the effect of conventional mulesing. "People presume that if they have sheep with a bare crutch then they'll get a sheep with a bare breech, but this doesn't necessarily happen," Mr Toland says. "It's only early days, but it appears crutch bareness may not be linked to breech bareness, and the heritability of breech bareness may not be quite as high as we'd like. "All the lambs in the trials have been breech- scored, and in the Dookie trial the lambs by our ram were only marginally barer than the average. In fact, another of our rams that was used in the Balmoral sire evaluation trial had lambs with higher breech scores. "Some sheep tend to bare off more as they mature, but we really want bareness to appear in the first year, because it is weaners that tend to have the most challenges in terms of stain and flystrike." In the Dookie trial, the management committee cut 10 to 15 per cent less wool, then people won't want them. "We also need to look at the impact of bare breeches on wool value because these sheep may cut a higher portion of fleece wool and produce less skirtings." Mr Toland admits that any attempt to breed productive sheep with a naturally bare breech is going to take considerable time. "I'm keeping an open mind, but there is no way we can use breeding to provide an alternative to conventional mulesing for woolgrowers by 2010. "Genetic change is very slow to achieve because it involves generations of animals, and this is compounded if the heritability of the trait we're selecting for is moderate to low." -- FIONA CONROY the bare-breech trait is under way at the Falkiner Research Station, NSW, as part of the sheep gene mapping project. Cojak is one of 20 rams being used to generate 5000 progeny for the project, all of which are being measured for more than 100 traits including breech score, wool and meat characteristics and parasite resistance. "The project is the largest sheep gene-mapping project in the world," Dr Fischer says. "Every lamb in the project has been blood-sampled and will be genotyped to help identify which DNA markers explain variation in which traits. "Ultimately this could result in information that would allow breeders to blood-test their animals to identify which ones were carrying genes for characteristics such as bareness, which may not express themselves until later in the animal's life." This technology could speed up sheep breeding where progress has traditionally been slow. "Genetics is a long-term approach, but it could offer the wool industry a long-term solution," Dr Fischer says. "In the future, woolgrowers will be able to select rams using Australian Sheep Breeding Values for resistance to breech strike." ú Phil Toland PHOTOS: UNIVERSITY OF ADELAIDE;'CALCOOKARA STUD', COWELL, SA BLOWFLY SUPPLEMENT BEYOND THE BALE 5
Apr 07 - May 07
Feb 07 - Mar 07