The sheep genome has finally made it on to the international genome sequencing research agenda. Traditionally, the small size of the international market for sheep products has limited investment in sheep genetic and genomic resources. Commercial sheep genomic resources have developed at a slower pace and to lower specifications than for other species of domesticated livestock.
However, the formation of the International Sheep Genomics Consortium (ISGC) heralds a new era in sheep genomic research, says Dr Orla Keane in TResearch, Teagasc's Research and Innovation magazine. Thanks to DNA Chip technology much progress has already been made. "The ISGC has used a newly developed chip to genotype approximately 3,000 sheep of 74 breeds from around the world in the Sheep HapMap and breed diversity project. The sheep genotyped included approximately 50 each of the Galway and Suffolk breeds sourced from Teagasc and University College Dublin flocks" explains Dr Keane.
"The technology also makes mapping the gene responsible for a single gene recessive trait relatively straightforward. Since the chip was released, the technology has been successfully used to map and identify the gene responsible for microphthalmia (a recessive disorder causing blindness) and chondroplasia (a disease resulting in dwarfism and deformity of the limbs) in the Texel breed, yellow fat in the Perendale breed, and the gene responsible for polledness. As part of the EU Seventh Framework Programme 3SR project (Sustainable Solutions for Small Ruminants), the technology is currently being utilised by Teagasc researchers, in collaboration with the ISGC, to map the gene responsible for increased ovulation rate in the highly prolific Cambridge flock at the Teagasc Animal & Grassland Research and Innovation Centre, Athenry," says Dr Keane.
Such examples of gene identification can have an immediate impact on the sheep breeding industry by allowing sheep breeders to screen animals for the genes and select replacement stock, cull or avoid at-risk matings based on the results. The technology is also currently being utilised by Teagasc and collaborators to identify genes underpinning polygenic traits, such as production traits and parasite resistance. Furthermore, the technology is a fundamental tool required for genomic selection, where animals are selected on genomic rather than phenotypic characteristics.
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