川西北高原阿坝州有一种牛犊，藏语叫做“杜勒”。这种牛犊是公犏牛和母牦牛或者母犏牛和公牦牛交配所生的下一代，其成活率非常低，大约只有千分之一左右。由于这种牛犊很难养活，所以它一生下来，往往都被当地人扔掉喂老鸹。 １９５８年我在阿坝州阿坝县麦尔玛牧区工作，当时 There is a calf in Aba prefecture in the northwestern Sichuan Plateau, called “Dürer” in Tibetan. This calf is the next generation of male and female yaks or maternal and yak crosses, with a very low survival rate of only about one in a thousand. Because of this calf is very difficult to feed, so it is born, are often thrown away by the locals to feed the elderly. In 1958 I was working in the pastoral area of ​​Myerma, Aba County, Aba Prefecture, at that time