Protein requirements of rainbow lorikeets, Trichoglossus haematodus

Abstract

The natural diet of rainbow lorikeets is low in protein but in captivity their diets contain relatively high concentrations of protein. A nitrogen (N) balance study was carried out to determine the protein requirements of lorikeets for maintenance. Five lorikeets were fed each of three diets, containing 3, 7 or 11 g egg white protein (100 g powdered diet)^–1 (‘as is’ basis). After 10 days on a diet, lorikeets were placed in metabolism cages and N intakes and N excretion determined over three days. From the regression of N excretion on N intake (y = 0.8664x+ 0.032) endogenous nitrogen loss (ENL) was calculated as 32 mg N (kg body mass)^–0.75 day^–1 and the maintenance N requirement as 240 mg N kg^–0.75 day^–1. The ENL is lower than that of other nectarivores but maintenance requirement is greater, indicating an unusually low digestibility for egg white protein (13.3%). Using a conservatively low digestibility of 4.5% for pollen, it can be calculated that 5–6 g pollen (dry matter) per day would provide the 8 mg N day^–1 required by a 150-g lorikeet to replace ENL. By eating 150–200 mL nectar, about 30% of requirement could be obtained.