Twins, maiden ewes key to genetic study

Are we classing young sheep progeny wrong?

That was the question Murdoch University researcher Bronwyn Clarke asked the neXtgen Head Shepherd Virtual Conference last Thursday.

Dr Clarke said her “thought-provoking” anomaly was directed at the classing of progeny from maiden ewes and twin lambs.

“These lambs are typically lighter, up to 6kg, and carry less clean fleece weight, up of 0.2kg, than single-born lambs, but they could theoretically provide genetic improvement,” she said.

Dr Clarke discovered the potential oversight from data collected from her work as WA site manager of the national Merino Lifetime Productivity project.

The $12.7 million national MLP project, to span from 2015 to 2025, was designed to understand and maximise lifetime performance of Merino sheep critical for productivity and profits.

It includes five Merino sire evaluation sites across the country, involving 135 different sires, with WA collecting data on 29 sires at the University of WA’s Ridgefield farm at Pingelly.

The MLP project was initiated on the back of industry changes, including more reliance on the classing of younger sheep.

Dr Clarke said relevance to maiden and twin lambs was essential.

“If were not accounting for this, there may be a problem that will be seen as a reduced rate of genetic gain,” she said.

Dr Clarke said the solution was for commercial producers to cull or select by classing from within single and twin mobs, and class lambs from maiden ewes separately from lamb mobs of older ewes.

“Ram breeders would also follow this procedure using Australian Sheep Breeding Values in conjunction with classing and recording of all different management groups,” she said.

“Classing off the bottom 20 per cent, rather than of all animals combined, would ensure genetic potential of twins and lambs born to maidens wasn’t lost.”

The MLP is backed by Australian Wool Innovation and Australian Merino Sire Evaluation Association.

The project is designed to capture lifetime data across diverse environments and Merino types in a bid to improve sheep understanding and deliver Merino ewe lifetime performance.

It also aims to underpin current breeding value technology across sheep types and environments.