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Beyond the Bale : June 2017
Wrinkle and Dags are the main causes of breech strike followed by Breech Cover and Urine Stain. AWI-funded research conducted at Armidale NSW (CSIRO) and Mt Barker WA (DAFWA) shows that every 0.1 reduction in breech trait scores, lowers the risk of lifetime breech strike for both mulesed and un-mulesed animals. Table 1 opposite is a summary of the Australian Sheep Breeding Values (ASBVs) of 158 AI sires from 27 Merino studs, from the MERINOSELECT website, listed in increasing Breech Wrinkle order. The variation in AI sire stud averages are large for Wrinkle, Cover and the key production indexes; Breech Wrinkle averages ranges from -1.2 to +0.9, Breech Cover from -1.3 to 0.3 and the indexes around 60 index points. The Wrinkle ASBV required to move to a non- mules operation without a large increase in chemical control, varies with factors such as climate, management systems, the size of the commercial property and nutritional value of the pastures. Wrinkle ASBVs can be higher for sheep raised on low protein and low energy country as the sheep 'express' less wrinkle when run in these environments. In production systems with high nutritional levels, more emphasis needs to be placed on lower Wrinkle ASBVs. There are 5 non-mules studs listed in the table with differing wrinkle scores; Studs Nine and Ten have an AI sire average Wrinkle ASBVs of -0.3, Stud Five averages -0.8 and Studs Two and One average -1.0 and -1.2. However, for sheep that are moderate or high in the key breech trait scores, any reduction in Wrinkle, Dag and Cover will reduce the lifetime risk of breech strike. The lower the score pre-mulesing, the lower the score post- mulesing. Breeding for good productivity as well as welfare is important for the commercial viability of the stud and its clients. There is a trend in the table that shows the lower Wrinkle studs have lower Adult Fleece Weight. But some studs buck the trend. Stud Seven has the highest Adult Fleece Weight at +24 with a relatively low Wrinkle at -0.4 showing the extent to which some studs and sires are bending the curve. and thereby reducing lifetime welfare risks and not sacrificing fleece weight. Studs with similar Adult Fleece Weight and Fibre Diameter can have considerable variation in Wrinkle. Studs Eight, Fourteen, Nineteen and Twenty Three have reasonably similar Adult Fleece Weights (+17, +15, +15 and +14) and Fibre Diameter (-0.8, -1.1, -1.1 and -0.7) but large variation in Wrinkle (-0.3, 0.0, +0.1, +0.4). There is also considerable variation between the studs' AI sires for dags and worm resistance. These traits can be important in high worm and dag country and not important in low dag and low worm country. There is a trend for lower Fertility with increasing Wrinkle and Fleece Weight. However Studs Thirteen, Seventeen and Twenty Two have similar NLW (5%, 4% and 3%) and Fleece Weights (9, 7, 11) but have reasonable differences in Fibre Diameter (-0.2, -2.0 and -1.1) and Wrinkle (0.0, 0.1 and 0.4), which again shows there are curve bending sires. Studs Twenty Four, Twenty Six and Twenty Seven have low Fibre Diameter (-3.0, -3.0 and -2.5) and high Wrinkle +0.5, +0.6 and +0.9. The path to non-mules without a high reliance on chemicals and other Dag reduction tools is a long one for most low Fibre Diameter Fine and Super Fine studs, but every 0.1 reduction improves lifetime welfare. As ASBVs become more robust with increasing data being collected by breeders (particularly Adult Fleece Weight, Breech traits and Fertility, at joining, scanning, lambing and weaning) and with the outcomes of the AWI Merino Lifetime Productivity project, the confidence and speed which breeders will be able to improve productivity as well as welfare traits will increase. Knowing how genetics and environment interact to create an animal's phenotype on a commercial property is an important step in knowing what targets to set, to maximise lifetime productivity and welfare. Breech Wrinkle and Dags are the key breech strike risk traits. Every 0.1 reduction reduces the lifetime risk of breech strike. As there is a general unfavourable relationship between fleece weight and wrinkle, it is important to pursue sires that are good for both (as well as fertility, growth, structure and the other resilience/welfare traits, in a balanced approach). There are sires and studs that bend this relationship; these "curve benders" are relatively higher in fleece weight and lower in wrinkle. REDUCE THE RISK OF BREECH STRIKE LOWER WRINKLE AND DAGS 40 ON FARM