*'''Essential amino acids''' are those that are required pre-formed in the diet as the animal either lacks the metabolic pathway to synthesise the given amino acid or is unable to make sufficient quantities for growth and normal physiologic/biochemical functions. | *'''Essential amino acids''' are those that are required pre-formed in the diet as the animal either lacks the metabolic pathway to synthesise the given amino acid or is unable to make sufficient quantities for growth and normal physiologic/biochemical functions. |