Abstract
Understanding a comparative approach to protein and amino acid requirements necessitates information on: (1) the animals' natural food preferences; (2) differences in digestive anatomy and physiology; (3) differences in protein and amino acid metabolism; and (4) details on the experimental design that has been used to investigate protein and amino acid requirements. This review specifically discusses potential differences in protein and amino acid metabolism and requirements, as well as details on experimental design. Details of the experimental design include such factors as: the technique used to quantify the requirement or effect, the diet composition and the species, breed and anthropometric details of the animals studied. Also, this review focuses on the broad base of knowledge available on rabbits (herbivores), dogs (omnivores) and cats (obligate carnivores).