Is Your Sheep Stressed? Just Ask It

　　Stressed-out sheep bleat out their anguish, U.S. researchers reported. They found that,like humans, sheep communicate stress by changing the timbre of their voices. Mark Feinstein of Hampshire College in Amherst,Massachusetts, said his findings could help farmers and, of course, the sheep they herd. An expert in bioacoustics*, Feinstein did his work at Teagasc, an Irish government agricultural research organization. He isolated sheep and separated

　　lambs from their mothers as part of his experiments ?then recorded their bleats. His recordings suggest that sheep express stress by altering the timbre of their vocalizations, or the overall quality of sounds, rather than by changing pitch or loudness. Stress can be measured by taking an animal's blood, but it would be much easier, cheaper and, yes, less stressful to simply listen, Feinstein said.

　　* bioacoustics：生物声学，研究对象为生物发出的声音及影响生物的声音，尤其是与生物间沟通有关的声音。