Sheep genome tells how they separated from goats

In a landmark discovery, scientists have cracked the genetic code of sheep, revealing how they became a distinct species from goats around four million years ago.

The decoding of the entire genetic make-up of domestic sheep for the first time can aid the development of DNA testing to speed up selective breeding programmes, helping farmers to improve their stocks, a study shows.

"Sheep were one of the first animals to be domesticated for farming and are still an important part of the global agricultural economy. Understanding more about their genetic make-up will help us to breed healthier and more productive flocks," said professor Alan Archibald, head of genetics and genomics at the Roslin Institute at University of Edinburgh.

In the study, researchers identified genes that give sheep their fleece and uncovers features of their digestive system, which makes them so well-suited to a diet of low-quality grass and other plants.

"It also builds the most complete picture yet of sheep's complex biology. Further studies using this resource could reveal new insights to diseases that affect sheep," Archibald added.

The global team, involving 26 research institutions in eight countries under the International Sheep Genomics Consortium, compared the sheep's genes with those of other animals, including humans, cattle, goats and pigs.

The analysis identified several genes that are associated with wool production.

"It also reveals genes that underpin the evolution of the rumen - a specialised chamber of the stomach that breaks down plant material to make it ready for digestion," researchers added in a paper published in the journal Science.