This refers to the protein content in the feed ration (food) eaten by livestock or poultry. Feed that contains “ideal protein” contains protein(s) that (when digested by the animal) yields all the essential amino acids, in proper proportions, for the growth and/or maintenance needs of that animal.
“Ideal protein” varies for different species (e.g., pigs require different amino acids/rations than chickens do). “Ideal protein” varies for different stages in the life of a given animal (e.g., poultry requires more sulfurcontaining amino acids, such as methionine, during stages when feather growth is at a comparatively high rate).
The animal’s requirement for one essential amino acid is proportionally linked to the animal’s requirement for another. Increasing the supply of one essential amino acid in the animal’s diet would improve that animal’s (growth) performance if no other amino acid(s) were limiting.