Not animals. Lignin is one of the organic substances with the highest content and the most difficult to decompose in plant wastes such as wood, rice husk and wheat straw. Because of its complex structure and high crystallinity, it has high heat and can be used as biomass fuel for power generation, heating and other purposes. According to the research, the combustion calorific value of lignin is 14- 17mj/kg, which is about 25% higher than that of wood, and it can be used as an important alternative energy source in some fields that need high heat, such as industry, air conditioning and heating. In addition, lignin is also used in the field of animals. For example, domestic animals such as donkeys and mules can eat wood fiber instead of refined coarse grains. Especially in rural areas where economic conditions are relatively backward and food resources are scarce, using lignin to enrich the protein content of main grains is beneficial to the growth and development, production performance and immunity improvement of livestock.