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Beyond the Bale : Aug - Sep 08
12 RoAd to 2010 BeyoNd the Bale Bare-breech trait proving highly heritable A four-year study that began with the bare-breech ram Cojak has proven that a genetic alternative to mulesing is possible as well as practical By Nicole Baxter A University of Adelaide trial has confirmed that the bare-breech trait displayed by animals at the ‘Calcookara’ Merino stud offers a viable genetic alternative to mulesing without adversely impacting on other economically important wool traits. The final report on the trial held on ‘Calcookara’ – Niel, Pat, Brenton and Jane Smith’s property, near Cowell, on South Australia’s Eyre Peninsula – shows that an enlarged, naturally bare and wrinkle-free area around the breech and down the channel through to the scrotum of rams, or mammary glands of ewes, is highly heritable. Report author and trial leader Professor Philip Hynd, director of the University of Adelaide’s Roseworthy Campus, says the results indicates that a genetic replacement for mulesing is not only possible, but could be achieved relatively rapidly in many Australian flocks without detrimental effects on fleece characteristics. The extensive four-year study began in 2004, after Niel and Pat Smith’s chance discovery of bare-breech ram Cojak in 2002, when they were selecting animals for a sheep sale. While at the time the Smiths were confident Cojak would offer a genetic solution to overcoming breech strike for the Merino industry, four years of research by the University of Adelaide’s Natasha Edwards, Michelle Hebart and Professor Hynd, was necessary before breeding could be promoted as a practical and permanent alternative to mulesing. “We needed to answer two important questions,” Professor Hynd says. “First, how heritable is the trait? Second, is bareness associated negatively with fleece weight and other economically important wool traits like micron, staple strength and style?” The first step in answering these questions was to establish a scoring system to identify bare-breech animals at a young age. Researchers developed a numbered (one to five), photo-based bareness scoring system (now included in the AWI Visual Sheep Scores booklet) and used it to score all available ewes, rams and progeny of ‘Calcookara’ sheep. Animals with wool-bearing skin on their breeches and inside back legs were given a score of five, while their wool-free counterparts were given a score of one. The second step was to measure how readily the bareness score was passed on to progeny (heritability). Results showed the trait was moderately heritable at lamb age (0.38) and highly heritable at hogget (0.53) and adult (0.45) scoring ages, with the researchers concluding that rapid progress could be achieved towards breeding a mules-free flock. “Nevertheless we were surprised at just how quickly the bareness scores improved at ‘Calcookara’ under the normal environmental and economic constraints that exist on many studs,” Professor Hynd says. “In just four years the proportion of animals scored from one to three increased from 27 to 67 per cent, while the very bare animals (scores one and two) increased from eight to 25 per cent of the flock.” Scoring at ‘Calcookara’: the University of Adelaide research team (from right) Aniek van diemen, Natasha Edwards and Professor Philip Hynd, with shearer Matt Story (left), scoring animals for bareness. PHoto:UNivERSity of AdElAidE Niel Smith says this was despite stud classer Bill Walker being asked not to put priority selection on the bare-breech trait. Instead, animals had to pass other selection criteria first. These included heavy-cutting, large, plain-bodied, highly fertile animals carrying long, white, soft, crimpy, 19 to 20-micron fleeces free from wool rot and dermatitis. Researchers from the University of Adelaide team are aware that many wool producers are concerned that selection for bare breech and plain-bodied animals will reduce fleece weights and compromise style. “The finding that this is not the case is important,” Professor Hynd says. “ the genetic correlations between bareness score and traits such as fleece weight, micron, co-efficient of variation of micron, comfort factor, staple strength and staple length were very low, which means producers can achieve improvements in all these traits at the same time as heading towards mules-free sheep. “It seems we have blown the myth that large-framed, plain-bodied, bare-breech animals cut less wool of poorer quality,” he says. “Breech score 1 animals are almost crutch-free and have the potential to significantly reduce production costs. Breech wool length is a major contributor to dags, and bare breeches will reduce dags and stain.” But he emphasised that care must be taken to ensure the bare-breech trait used is in fact the same genetic trait as that seen at ‘Calcookara’. “We are aware that there are other animals that become bare over the entire body and we must ensure that these are not mistakenly selected for,” he says. The Smiths are no longer mulesing their animals, indicating their confidence in the bare-breech trait. More information: executive summary of the aWI- funded Calcookara Project,www.wool.com.au; Niel Smith, 08 8629 2384, firstname.lastname@example.org, www.calcookara.com.au; Philip hynd, email@example.com Table 1 Ram wool details from ‘Hilton Heath Stud’, Mount Pleasant, SA ram Poll 101 horn 83 Poll 21 SCore mICroN 1 3 2.5 20.2 17.6 18.2 Sd 3.0 3.2 3.3 CV 17.6 18.3 17.1 CF 99.5 99.6 99.8 Naturally the question will be asked: are these findings consistent with what other woolgrowers have discovered? During 2006, near Katanning, WA, Chris and Eric Patterson of ‘Woolkabin Stud’, decided they wanted to enhance their large, plain-bodied sheep with the bare-breech trait by laproscoping 150 ewes to ‘Calcookara’ sire Garrett. Of the 10 Reserve Show Rams for 2008, four were bred by the bare-breech sire Garrett. The resulting progeny not only displayed the bare-breech trait, but also produced quality wool, allowing the Pattersons to achieve their average fleece weight and prompting the pair to acquire two ‘Calcookara’ sires with 20.7 and 18.4-micron wool. In SA, Trevor and Matt Fiebig of ‘Hilton Heath Stud’, based at Mount Pleasant, reported similar results after buying 50 doses of semen during 2005: 25 each from ‘Calcookara’ sires Garrett and Cojak. Fifty bare-breech ewes with good coverage of belly wool were artificially inseminated and went on to produce three young potential sires, with good bareness scores at an early age (see Table 1). Checking the ewe hoggets at crutching revealed most had a bareness score of two, which Niel Smith says should reduce to a score of one with age without any loss of wool cut or quality. Poll 101 has produced one potential sire rising 12 months, with a bare-breech score of one, and several others showing promise. Anecdotally there may be the added bonus that bare- breech animals are more fertile and that lamb survival may be enhanced in these animals. The Fiebigs have noticed lambing percentages in their bare-breech mob appear five to 10 per cent higher than conventional mobs. “If, as we expect, the results from ‘Calcookara’ stud apply to other bloodlines and environments, the industry now has the genetic tools to enter the post-mulesing era with confidence,” Professor Hynd says. ú Key messages ú Genetic studies have indicated that it is possible to produce bare-breech animals that do not lose fleece weight and produce long-stapled, stylish wools of low micron ú this has been confirmed on large-scale commercial properties and studs ú the bare-breech trait is highly heritable, so rapid changes can be made towards the trait
Jun - July 08
Oct - Nov 08