Abstract: Twenty four little-tail sheeps weighing approximately 20.5 kg each ,were used in a 2×2 factorial design experiment to determine the effect of urease inhibitor and roughage diets on growth performance and internal organ in fattening sheep. The four rations containing corn stalk or alfalfa with corn stalk as roughage diets with or without urease inhibitor were fed in feeding trial. The result showed: ①Adding the urease inhibitor or alfalfa to diets can increase the average daily gain of fattening sheep, the sheeps fed the ration containing alfalfa with corn stalk has higher average daily gain than the sheeps fed corn stalk . ②The roughage diets and urease inhibitor both have no effect on internal organ of fateening sheeps. ③Adding the alfalfa to the diets can increase the income of farmer more than urease inhibitor.

Key words: urese inhibitor; roughage; fattening sheep; growth performance; internal organ