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Lethal sheep genes targeted in full genome sequencing

Monday 20th of October 2014

Full sequence genotype testing of a select research flock is hoped to deliver significant improvements to the reproductive performance of the national ewe flock through the identification of lethal genetic mutations.

Gene mutations can prevent an embryo from fully forming and therefore reduce conception rates in a flock.

Through its genomic sequencing research, the Cooperative Research Centre for Sheep Industry Innovation (Sheep CRC) aims to enhance DNA testing so that breeders can identify breeding stock carrying high-risk recessive genes.

Sheep CRC Chief Executive James Rowe said this would enable breeders to remove these rams from their breeding programs and thereby breed the recessive gene out of their flock make up.

“An embryo carrying a double recessive gene will not fully form, and as a result breeders do not ever see progeny on the ground with this gene combination – they are often none the wiser as to the true cause of lower conception rates in their ewe flock,” Prof. Rowe said.

“A DNA test identifying sheep with potentially lethal gene mutations would allow breeders to intervene early and join their ewe flock with a more appropriate ram. This could lead to a five per cent increase in reproductive efficiency.”

Operating as part of the Federal Department of Industry’s CRC program, the Sheep CRC is a collaboration of 38 Participants from industry, government and the commercial sector. It is working to increase the productivity and profitability of the industry through adoption of new technologies in both the meat and wool supply chains.

Previous genetic research has already identified potential lethal mutations in Border Leicester, Polled Dorset and Merino breeds.

Dr Hans Daetwyler, Senior Research Scientist at Victoria’s Department of Environment and Primary Industries, said these findings would be validated and fine-mapped using a high density DNA test and full genome sequence data as part of the new Sheep CRC research project.

"An early success story from dairy cattle sequencing has been the identification of several mutations affecting recessive disorders including embryonic lethals,” Dr Daetwyler said. “We expect a similar impact of whole-genome sequence data for the Australian sheep breeds through the Sheep CRC extension.”

The Sheep CRC will have the advantage of working closely with the Dairy Futures CRC, and applying the lessons it learned when obtaining similar findings from the full genome sequencing of a select herd of 250 dairy bulls.

Between 250 and 500 rams from the Industry Resource Flock will be tested, providing new data for a range of genetic traits which will contribute over coming years to enhanced accuracy in breeding values.

“Having a large range of traits already available to us from the Sheep CRC’s Information Nucleus research really does improve our ability to track down the variants in the sequence that can cause the differences between animals for a number of traits,” Dr Daetwyler said.

“This has also been demonstrated in dairy cattle data and it bodes well that the industry’s investment in trait recording will be relevant for many years to come.”

More information on DNA testing of sheep is available from www.sheepcrc.org.au

Media contact: Michael Thomson on 07 4927 0805 / 0408 819 666

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