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

Marquardt (1994) added enzyme preparations to broiler barley rations, which increased broiler weight gain by 46%, apparent metabolic energy by 33%, and fat digestibility by 193%. In contrast, a corn-based diet supplemented with this enzyme had no effect. Annison (1991) added enzymes to broiler barley-based diets and increased daily gain by 10.44%, which was roughly equivalent to that of corn-based diets. Liu Mei reported that the feeding effect of adding 0.05% compound enzyme preparation to the barley-based ration of broilers reached the level of the corn-based ration, and the feed cost was also reduced. Wang Qingji (1997) studied the effect of adding enzyme preparations on the weight gain of chicks in hammer-type basal diets.

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