A named protein identifies the source species: "chicken," "salmon," "lamb," "beef," "duck." Unnamed protein sources hide the species: "meat," "poultry," "animal," "fish." Named sources are the strongest single signal of ingredient quality because they imply traceable supply chains and consistent formulation. Generic protein sources can change batch to batch depending on what's cheapest, which causes problems for pets with allergies and reflects poorly on manufacturing rigor.