Get the wrinkles out at lamb marking

Breech wrinkle is one of the important factors determining how susceptible a sheep will be to breech strike. Lamb marking provides an ideal time to determine how wrinkly your sheep are and identify those lambs that need to be culled or kept out of the breeding flock.

Breech wrinkle is scored on a scale from 1 to 5. Score 1 is a plain breech lamb with no wrinkle whilst a Score 5 has extensive wrinkling and heavy folds of skin at the tail set and hind legs. A ‘Visual Score Guide’ has been developed (see diagram). A full version is available on the Flyboss website.

Aiming for a flock with an average breech wrinkle of less than Score 3 will reduce the incidence of breech strike. Use coloured ear tags to help identify the wrinkle score groups. Cull and/or keep the higher wrinkle score lambs out of the breeding flock. Some consideration may be given to not mulesing lambs with breech wrinkle, Score 1 & 2.

Environmental effects also need to be taken into consideration when scoring lambs and setting a ‘cull’ level. Average scores may differ within a mob and across years. An environmental effect example is where twin born lambs on average are 0.3 to 0.5 of a score plainer than a single born lamb. Other effects include lambs from maiden ewes are 0.2 to 0.3 score plainer compared to lambs from older ewes, and lambs born in a drought/restricted feed are 0.5 to 1.0 score plainer compared to those born in good feed conditions.

Breech wrinkle and body and neck wrinkle are closely related and highly heritable. Other traits that are also have an impact on flystrike include dags, breech cover, tail cover and wool colour. Dags, breech cover and wool colour are also moderately to highly heritable. This provides an opportunity to select and breed sheep that are more flystrike resistant. If breech wrinkle scores or breeding values are not available from your ram breeder you can assess neck wrinkles to identify low breech wrinkle rams.

Whilst there is a slightly negative relationship between wrinkle score and clean fleece weight it is less than the negative relationship between fibre diameter and clean fleece weight. Despite this, there are plain bodied sheep with high fleece weights out there in the industry.

Whilst the issue of ceasing mulesing is relatively quiet in the media at the moment, the issue has not gone away. Pressure from minority groups will continue until the practice ceases. Scoring breech wrinkle at lamb marking now will give producers a distinct advantage in the future.

For further information refer to FlyBoss.

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