A lamb grazing system in sainfoin stubble fields was studied from the stand point of view of agricultural energetics. Results from the experiment indicate that the output/input ratio of energy from four treatments of RM, SM, RO and SO were 22.34%, 19.98%, 16.67% and 17.51%, respectively. The ratio of rotational grazing was 1.24 times over that of set stocking. It would be more effective to increase energy input including the input of direct and indirect physiological energy to those Lamb under rotational gr...