In this study, crude protein and digestible crude protein production (kg/da) of barley, wheat, rye, triticale and oat were measured at booting and dough stages of maturity and their protein fractions were determined according to Cornell Net Carbohydrate and Protein System. The average crude protein contents of cereal forages were 42% lower (P<0.05) at dough stage than booting stage while crude protein production decreased (P<0.05) by only 10% from dough stage to booting stage of maturity. However, digestible crude protein production was similar (P>0.05) in both periods. The crude protein quality of wheat and oat was higher than other cereal forages at the booting stage. These results suggest that time of harvest can be arranged according to cereal forages with desired protein properties that change with maturity stage.