Cornejo, Juan (2012-05). Insights on Psittacine Nutrition through the Study of Free-living Chicks. Doctoral Dissertation.
The Psittacidae is one of the most endangered families of birds in the world. Knowledge of its nutrition is important for understanding their survival and productivity in the wild, as well as for their adequate husbandry in captivity. Hand-rearing is a common practice for this group. However, research on their requirements is limited. Analysis of the crop content of chicks can provide new insights into psittacine nutrition, but it is limited by the small sizes of samples which can be obtained. We sampled the crops from free-living chicks of scarlet macaws and red-and-green macaws from southeastern Peru, Cuban parrots from the Bahamas, lilac-crowned parrots from northwestern Mexico, and thick-billed parrots from northern Mexico. The predicted metabolizable energy, protein, fat, minerals, profile of essential amino acids and profile of fatty acids of the crop samples, as well as from 15 commercial hand-rearing formulas, were analyzed and contrasted. Near Infrared Spectroscopy was shown to be a valid technique for the nondestructive, low cost prediction of a variety of nutritional attributes of crop samples as small as 0.5 g dry weight, expanding the possibilities of wild animal nutrition research. The diets of the five studied species presented remarkable similarities and common patterns. The predicted dietary metabolizable energy and fat concentrations were particularly similar among species, the thick-billed parrot being the one with the most unique nutrient profile. The fatty acid profile of the crop contents differed markedly among genera, with the thick-billed parrot closer to the macaws than to the parrots. In comparison with the crop samples, the hand feeding formulas presented lower fat, Mg, arginine, and valine concentrations. The wide variation in nutrients suggests that there is not yet a consensus among manufacturers concerning the correct nutrition for growing psittacines. It is suggested that a single formulation could be used to hand-rear macaws and parrots from half its nesting time to fledging, and further research should focus on their nutrition during the first half. Our results suggest that manufacturers should evaluate if increasing the concentrations of crude fat, Mg, arginine, and valine in commercial formulas enhances psittacine chick growth and health.