Seventy male, wether and female crossbred lambs of Borderdale(♂) × Mongolia sheep (♀), Poll Dorset(♂) × Mongolia sheep (♀) were selected to evaluate the fattening method and effect of high-quality mutton lambs. Local lambs(Mongolia lamb,♂) were selected as control group. Single factor design was adopted. (ⅰ) One feeding experiment was conducted using 10 of each crossbred lambs which were 5-month and 3-month old to compare the growing performance under barn feeding condition and grazing plus supplement feed...