Predicted metabolizable energy density and amino acid profile of the crop contents of free-living scarlet macaw chicks (Ara macao)


J. Cornejo, The Schubot Center, Department Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4467 TAMU, College Station, TX 77843-4467, USA. Tel: 979 458 0904; Fax: 979 845 9231; E-mail:


Hand rearing of neonates is a common practice for the propagation of psittacines. However, nutritional requirements for their growth and development are not well understood, and malnutrition is common. We analysed the amino acid (AA) profile of the crop contents of 19 free-living scarlet macaw (Ara macao) chicks, 19–59 days old. Predicted metabolizable energy (PME) density was 16.9 MJ/kg DM and true protein (total AA protein) 8.3 g/MJ PME. Crude protein (CP) was 10.0 g/MJ PME, lower than the requirements of 0- to 12-week-old leghorn chicks but not different than the requirements of growing budgerigars (Melopsittacus undulatus) and lovebirds (Agapornis spp.). The mean concentrations of leucine, isoleucine, threonine, lysine (Lys) and methionine on a PME basis were below the minimum requirements of 0- to 12–week-old leghorn-type chicks. The calculated PME density of the samples did not vary with age. However, there was a significant negative correlation between the average age of the chicks and the Lys concentration. We conclude that the lower CP and AA densities compared with poultry could result from a combination of (i) differences in the essential AA composition of the body tissues, (ii) adaptations that allow the birds to grow on low-protein food sources and (iii) suboptimal nutrition of these free-ranging chicks.