中文摘要：

对阿拉善荒漠草地38种优势牧草氨基酸总量、必需氨基酸、含硫氨基酸、限制性氨基酸含量及必需氨基酸指数（EAAI）的组成特点进行了研究。结果表明，氨基酸总含量为2．47％～22．50％；各科牧草氨基酸总含量顺序为：百合科〉豆科〉蒺藜科〉菊科〉禾本科〉藜科〉蔷薇科〉柽柳科〉蓼科；必需氨基酸含量为0．97％～8．92％，同时满足EAA／NEAA〉60％，EAA／TAA〉40％的牧草有23种；各科牧草必需氨基酸含量占氨基酸总量比值依次为：蔷薇科〉菊科〉藜科〉豆科〉蓼科〉禾本科〉百合科〉柽柳科〉蒺藜科；含硫氨基酸含量为0．28％～1．40％，含硫氨基酸占氨基酸总量比值从高到低依次为柽柳科、藜科、蓼科、豆科、蔷薇科、蒺藜科、禾本科、菊科、百合科；内蒙古白绒山羊限制性氨基酸总含量为0．70％～3．22％；38种牧草的EAAI值，对羊肉为0．914～1．010，对山羊绒为0．976～1．250，对山羊毛为0．951～1．219。阿拉善荒漠草地牧草是当地白绒山羊和绵羊优良的饲料来源，对山羊毛和羊绒的产量和品质有重要的作用。

英文摘要：

The characteristics of total amino acids, essential amino acids, sulfur amino acids, limited amino acids and essential amino acid index （EAAI）of 38 forages in the Alxa desert grassland were studied. The total amino acid content ranged from 2.47% to 22.50% and declined in the order： Liliaceae〉Leguminosae〉Zygo- phyllaceae〉Asteraceae〉Gramineae〉Chenopodiaceae〉Rosaceae〉Tamaricaceae〉Poygonaceae. The essential amino acid content ranged from 0.97% to 8.92%. There were 23 forages with EAA/NEAA〉60% and EAA/ TAA〉40%. The content ratio of essential amino acid to total amino acid declined in the order. Rosaceae〉Asteraceae〉 Chenopodiaceae〉Leguminosae〉Polygonaceae〉 Gramineae〉 Liliaceae〉 Tamaricaceae〉 Zygophyllaceae. The sulfur amino acid content ranged from 0.28G to 1.40%, the content ratio of sulfur amino acid to total amino acid followed the order ： Tamaricaceae〉 Chenopodiaceae〉 Polygonaceae〉 Leguminosae〉 Rosaeeae〉 Zygophyllaceae〉Gramineae〉Asteraceae〉Liliaceae. The total content of limited amino acids in Inner Mongolian White Cashmere Goats ranged from 0.70% to 3.22%. The EAAI value of 38 forages to mutton, cashmere and hair ranged from 0. 914--1. 010, 0. 976--1. 250 and 0. 951--1. 219 respectively. Forages in the Alxa desert grasslands play an important role in yield and quality of cashmere and hair. They are an excellent feed resource for local Cashmere Goats and sheep.