The low feed efficiency of barley compared with maize is due to the high content of NSP(non-starch polysaccharide) in barley. The NSP of barley is not only unable to be digested by the endogenous enzymes of the animals, but also reduces the growth performance of the animals by increasing the viscosity of the intestinal contents and reducing the feed intake of the animals, thus reducing the feeding value of barley.

Marquardt(1994) added enzyme preparation to broiler barley-type diet, which increased broiler weight gain by 46%, apparent metabolizable energy by 33%, and fat digestibility by 193%. On the contrary, corn-based diet supplemented with this enzyme had no effect. Annison(1991) added enzyme to the broiler barley-type diet increased daily weight gain by 10.44%, which was approximately equivalent to that of the corn-type diet. Liu Mei reported that the feeding effect of adding 0.05% compound enzyme preparation to broiler barley-type basal diet reached the level of corn basal diet, and the feed cost also decreased. Wang Qingji (1997) studied the effect of adding enzyme preparation to the mallet-type basal diet on chicks' weight gain. 

The results showed that the increase of thyroxine and immunity of chicks aged 7-21 days was higher than that of barley-fed chicks. The level of T3 in the enzyme plus group was higher than that in the barley basal diet group, and the lymphocyte conversion rate was 24.57% higher than that in the barley basal diet group. Classen et al. (1988) added 0.25g/kg NSP enzyme preparation to 9 different barley-based diets, and the experimental results showed that broiler weight increased by 12.3% on average and feed conversion rate increased by 5.5%. Graham(1991) added an avidase preparation to the barley-based diet and showed that the egg production rate of the experimental group was 3% higher than that of the corn-based diet group.