Protein requirements of three species of parrots with distinct dietary specializations
Dietary protein deficiency is considered a major obstacle in the evolution of highly specialized nectarivorous and frugivorous birds. Proposed physiological mechanisms that enable such specialists to subsist on low-protein diets....
include minimized endogenous protein losses, which contribute to reduced protein requirements. These traits were compared among nectarivorous red lories (Eos bornea), frugivorous Pesquet's parrots (Psittrichas fulgidus), and granivorous budgerigars (Melopsittacus undulatus). The results of this trial suggest that, relative to budgerigars, red lories and Pesquet's parrots have low endogenous protein losses and reduced crude protein (CP) requirements. Based on nitrogen balance analyses, diets containing 1.0%, 3.2%, and 8.2% CP (on a dry matter (DM) basis) would meet the minimal protein requirements for maintenance for red lories, Pesquet's parrots, and budgerigars, respectively. Low endogenous protein losses and reduced protein requirements are effective physiological adaptations that allow birds such as red lories and Pesquet's parrots to specialize on low-protein foods.
Title: Protein requirements of three species of parrots with distinct dietary specializations
Author: Gregory S. Pryor