Abstract: In the herbivore breeding in Bayannaoer City of Inner Mongolia,there are unreasonable proportion of roughage,feeding animals mainly with straws,serious shortage of high-quality forages and other issues.To solve these problems,weight gain of lambs was determined after they were fed roughage with different formulas.This study will provide reference for scientific and rational adjustment and optimization of the structure of roughage,transformation of growth mode of animal husbandry,effective promotion of the development of forage and upgrade of forage quality,and increasing proportion of high-quality forage or dedicated pasture,which further increases livestock breeding efficiency.