When protein in feed is insufficient, it is mainly manifested as slow growth, weakness, dim feathers, decreased disease resistance, susceptibility to infectious diseases and death, emaciation, anemia, edema, bleeding and metabolic disorder. The growth and development of young birds are blocked, and they are afraid of cold and crowding, and their body temperature drops, resulting in a large number of deaths; Adult poultry lose weight, anemia, egg production drops sharply or stops laying eggs, and eggshells become soft and thin, which is easy to cause a series of diseases. Autopsy showed that the blood was thin, the coagulation was slow, the bird was thin, and there was almost no adipose tissue in the whole body. The original adipose tissue became gelatinous infiltration, and hydrops appeared in pericardial sac, chest cavity and abdominal cavity.