No quick fixes in breeding for bare breech
Victorian stud breeder Phil Toland (pictured) is the first to admit that breeding for a bare breech in Merinos is not going to give the wool industry results overnight.
The Violet Town producer joins about 2000 Merino ewes a year and has more than 10 years' involvement in the assessment of Merino sires through the National Sire Evaluation Program.
When the call went out from AWI for growers to watch out for any rams in their flock with a bare breech, one ram caught Mr Toland's eye. The ram was the result of an outcross sire used in an AI (artificial insemination) program at Toland Merinos and was extremely bare in the breech area.
The ram was sent for semen collection and is one of the sires being used by Tim Dyall at CSIRO Livestock Industries in New England, NSW, and by the Department of Agriculture and Food, Western Australia, in Mount Barker, to investigate bare-breech heritability.
Mr Toland has been chairman of the local North East Dookie sire evaluation committee for more than 10 years. The ram's semen was also used in the Dookie sire evaluation, effectively linking all three sites.
"It seemed like a good opportunity to put the ram in the trial and see what he could do," Mr Toland says.
"It also meant we could trial this approach in Victoria alongside NSW and WA."
The lambs sired by the ram were born at the various sites during winter and spring 2006, and have since been weaned and scored for bareness in the breech and crutch as well as for wrinkle.
The crutch area assessed in the scoring system is the area between the back legs and the back of the udder in ewes, which is subject to urine stain. The 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 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 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."
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