Breeding for Wool

Genetics offers wool producers the opportunity to make permanent improvements relatively easily in a range of important wool traits.

Sires can be chosen for both measured and visually assessed traits using Australian Sheep Breeding Values (ASBVs) through MERINOSELECT from Sheep Genetics.

The already well-used measurements of fibre diameter and fleece weight can be combined with traits such as staple length and staple strength, as well as traits to improve the Merino’s resistance to worms and flystrike.

ASBVs for a range of visual wool traits, including wool colour and character, are also being developed by Sheep Genetics with data from the Sheep CRC’s Information Nucleus flocks, other research flocks and industry flocks. If you are only recently starting to use ASBVs to aid your selection of rams, use just one or two ASBVs for the traits most important to your breeding program while you become familiar with their use.

Also, use one of the Indexes as a guide to overall performance of a ram—ask your stud breeder which index supplied is most relevant to your production system.

The ASBV values relate to the raw values for a trait—if you want to improve the trait by making it larger, e.g. bigger weights, then a bigger ASBV value is better. If you want the trait to improve by making it smaller, e.g. lower worm egg counts, lower fibre diameter, fewer wrinkles, then you want a lower, more negative ASBV value for that trait. The actual values are less important that the differences between them for each ram.

The Sheep CRC is also developing new industry information for next-to-skin comfort, handle and whiteness in wool garments.

Wool producers should also consider the value of adding meat traits into their selection. As cull lambs are bringing a significant injection of income to the wool operation, rapid growth and good eye muscle depth are important traits. These can be selected by choosing a stud that offers weight and eye muscle ASBVs. For most Merino enterprises, the yearling weight (YWT) ASBV and yearling eye muscel depth (YEMD) ASBV are ideal traits to use. For enterprises with larger framed-Merinos, able to finish surplus sheep at 7–10 months of age, consider using the post weaning weight and eye muscle ASBVs.

To avoid increasing the adult ewe size (that would decrease the number of ewes that can be carried) choose high post weaning weight (PWT) or YWT ASBVs, but moderate adult weight (AWT) ASBVs.

Another important trait to consider for Merinos is fat. The ability of a ewe to store fat to draw on in tougher times adds to her resilience and reproductive performance. When selecting rams, look for a higher yearling fat (YFAT) ASBV.

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