Sheep genes reveal room for improvement

Sheep are among the most genetically diverse domesticated animals, and further breeding could yield more meat and wool, according to a new US study. The study, published Tuesday in the online journal PLoS Biology, maps out the ancestry of sheep going back 11,000 years, to the origins of animal husbandry, and shows that there may still be room for improvement. "Most modern sheep breeds have maintained high levels of genetic diversity, in contrast to some breeds of dogs and cattle that generally have higher levels of inbreeding," lead author James Kijas of Australia's national science agency, CSIRO, said in a statement. The study documents the rich history of sheep breeding, including the selection for genes controlling coat color, body size, reproduction and the lack of horns -- one of the earliest innovations. Kijas said the high level of genetic diversity means that there is still room for further selection -- the breeding of sheep that produce more meat, for example, or that are resistant to certain diseases. The team traced the relatedness of nearly 3,000 sheep from 74 breeds by comparing 50,000 DNA sites across the genome.