Animal protein mainly comes from poultry, livestock and fish meat, eggs, milk. Its protein composition is mainly casein 78 ~ 85%, which can be well absorbed and used by adults. What's more, animal protein has a complete range of essential amino acids in a reasonable proportion, so it is easier to digest, absorb and use than general plant protein, and its nutritional value is relatively high. Generally speaking, protein in meat (such as fish and beef) and protein in milk have amino acid scores ranging from 0.9 to 1.0.