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Beyond the Bale : December 2010
21 December 2010 BEYOND THE BALE ON-FARM FAST FACTS l Sheep Genetics has released breeding values, including ASBVs for dags and breech cover. l Dags and wrinkle are the indicator traits most strongly associated with risk of flystrike. l Adoption of the early breech wrinkle ASBVs has been rapid by MERINOSELECT members. Sheep Genetics has released breeding values (BV) for: l dags (ASBV) l breech cover (ASBV) l greasy wool colour (research BV) l fleece rot (research BV); and l wool character (research BV). These add to breech wrinkle ASBV that was released in 2009. Breech wrinkle, dags, breech cover and greasy wool colour have all been shown to be associated with risk of flystrike in AWI's 'Breeding for Breech Flystrike Resistance' trial sites at Mt Barker, WA (run by the Department of Agriculture and Food, Western Australia) and Armidale, NSW (run by CSIRO) - see bar graphs to the right. Dags and wrinkle are most strongly associated with risk of flystrike. Their relative importance depends on the sheep and the country in which they are run. In high dag regions, dags are likely to be the most important risk; in low dag regions, wrinkle is likely to be the most important. The effect of these traits on flystrike risk is more pronounced when a sheep has a combination of them. Unmulesed sheep that are wrinkle 2 score and less, dags 2 score and less, and breech cover 3 score and less, have similar low risks of flystrike to mulesed "controls" at Mt Barker and Armidale. ASBVs released by Sheep Genetics for MERINOSELECT enable growers to achieve the right balance between selecting for improved flystrike resistance and the core production traits such as fleece weight, fertility, fibre diameter, staple strength and carcass. The ASBVs encourage the 'fastest' gain possible. Negative ASBVs for wrinkle, dag and breech cover will result in sheep with lower wrinkle, lower dag and lower breech cover. These traits need to be balanced with other visual traits and productive traits, some of which are included in the table below for four AI sires. Results for all animals with sufficient data and linkage are published on the Sheep Genetics website and will soon be included in breeders' reports to members. Adoption of the early breech wrinkle ASBVs by MERINOSELECT members has been rapid. Sixty six per cent of the 2009 drop animals have been assessed for early breech wrinkle. Breeding for low dags will be challenging because the incidence of dags is strongly associated with the environment, which can quickly swamp "genetic merit" particularly in high dag country (high winter rainfall Mediterranean climates). It will take a considerable amount of time to breed low dag sheep (2 score or less) in high dag country, but breeders now have the tools to head in this direction much faster. In the meantime, dag reduction in these high dag regions can be achieved by good worm control, breech modification, timing of shearing and crutching, and grazing management. Dags can also be caused erratically by larval hypersensitivity (immune response reaction when worm numbers are low and larval intake is increasing coming into winter) however there are limited management options to reduce dags due to hypersensitivity. Australian Merino Sire Evaluation Association, AWI's 'Breeding for Breech Flystrike Resistance' trial sites and the eight Sheep CRC Information Nucleus sites have contributed most of the data for the newly released traits and the analysis methodology has been created by the Sheep Genetics Technical Committee with major inputs from the Animal Genetics Breeding Unit (AGBU). More information: www.sheepgenetics.org.au www.wool.com/flystrike New breeding values released ARMIDALE FLYSTRIKE RISK AN EXAMPLE OF ASBV RESULTS ON THE MERINOSELECT WEBSITE: FLOCK/ PROGENY YCF W YFD YSS NLW YEMD Y FAT YWEC EBWR LCOVER LDAG 7% INDEX RAM 154 22/1059 14 -1.9 0.0 +3% -0.7 -0.1 -34 -1.2 -0.6 -0.6 159 RAM 420 13/1217 13 -1.9 3.6 +3% +0.8 +0.6 -75 -0.1 -0.1 +0.2 166 RAM 400 15/487 22 -0.7 -5.0 +2% +0.5 -0.4 +1 -0.7 -0.1 -0.1 149 RAM 351 40/3404 32 -0.2 2.1 +26% +0.9 0.6 -51 0.0 -0.6 -0.2 206 AVE 09 DROP 8 -1.1 0.2 +2% +0.3 +0.3 -11 -0.1 0.0 0.0 129 TOP 20% 09 DROP 15 -1.9 2.4 +5% +1.1 - -34 -0.4 -0.2 -0.2 143 YCFW (Yearling Clean Fleece Weight), YFD (Yearling Fibre Diameter), YSS (Yearling Staple Strength), NLW (Number of Lambs Weaned), YEMD (Yearling Eye Muscle Depth), YFAT (Yearling Fat Depth), YWEC (Yearling Worm Egg Count), EBWR (Early Breech Wrinkle), LDAG (Late Dags) and LCOVER (Late Breech Cover). MULESED UN-MULESED 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1 2 3 4 5 BREECH STRIKE PREVALANCE POST-WEANING BREECH WRINKLE SCORE 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1 2 3 4 5 BREECH STRIKE PREVALANCE POST-WEANING DAG SCORE Dags -- 2006-09 drop weaners Breach wrinkle -- 2006-09 drop weaners