Protein requirements for Blue-fronted Amazon (Amazona aestiva) growth

Nutrition of free-living Neotropical psittacine nestlings and implications for hand-feeding formulas

Psittacidae is one of the most endangered families of birds in the world. Knowledge of their nutrition is important for understanding their survival and productivity in the wild, as well as for their adequate husbandry under human care. Hand-rearing is a common practice for psittacines, however research on their nutrition is limited. We analysed the predicted metabolisable energy, crude protein, crude fat, minerals and the essential amino acid profiles of the crop contents from free-living nestlings of scarlet macaws (Ara macao) and red-and-green macaws (Ara chloropterus) from southeastern Peru, Cuban Amazons (Amazona leucocephala bahamensis) from the Bahamas, lilac-crowned Amazons (Amazona finschi) from northwestern Mexico and thick-billed parrots (Rhynchopsitta pachyrhyncha) from northern Mexico. The crop content of the different parrot species displayed remarkably similar nutritional profiles, considering their diversity in habitats, geographic ranges and food sources. The crude protein and crude fat concentrations in crop samples were particularly similar for the Ara and Amazona species, while the thick-billed parrot stood out for its higher crude fat and lower crude protein content. Wider variations were found among the concentrations of sodium (Na) and iron (Fe), proline and tryptophan. Compared with the requirements of 6-12 weeks leghorn chickens, all free-ranging parrot diets contained lower crude protein, calcium (Ca), potassium (P) and Na concentrations. The hand-feeding formulas contained lower crude fat, magnesium (Mg), arginine, valine and phenylalanine concentrations, as well as much higher levels of Ca and zinc (Zn), in comparison with parrot crop samples. Our data suggest that a single formulation could be used to hand-rear Ara and Amazona sp. of 3 weeks of age and older, while a different formulation would likely be more appropriated for Rhynchopsitta sp. Experimental studies should evaluate if increasing the concentration of crude fat, Mg, arginine, valine and phenylalanine enhances psittacine chick growth and health.

Assessment of Three Diet Types on Constitutive Immune Parameters in Captive Budgerigar (Melopsittacus undulatus)

Proper diet and nutrition are essential for maintaining the health of captive birds, but specific nutritional requirements can vary by species. Our knowledge of avian nutrition is predominantly based on data collected from gallinaceous birds, which is the primary basis for the dietary recommendations for companion birds, such as budgerigars (Melopsittacus undulatus) and other psittacine birds, potentially leading to a higher risk of malnutrition. In the wild, budgerigars eat predominantly Australian grass seed of the Astrebla genus, which may not be similar to the commercially available food fed to captive budgerigars, both in nutrient content and in their physiologic effects. In this study, we examined the relationship between diet type and immune function by separating 36 budgerigars into 3 dietary treatments: 1) Roudybush formulated pellet diet (Roudybush BirdFood Inc, Woodland, CA, USA), 2) Kaytee Forti-Diet Pro Health seed mix (Kaytee Products Inc, Chilton, WI, USA), and 3) a natural seed diet containing fresh canary grass, flax, nyger, oat groats, and white millet seeds. We monitored body weight, measured the microbial killing ability of whole blood by Escherichia coli and Candida albicans, and collected blood smears to assess white blood cell counts during a period of 8 weeks. Overall, we observed no significant effects of the 3 different diets on bird microbial killing ability or on white blood cell counts, suggesting similar health outcomes for budgerigars that consume mixed seed and those that receive pellet-based diets during this relatively short-term study.

Feed processing effects on digestibility, palatability, excreta fermentation products and blood parameters in blue-fronted amazon parrots (Amazona aestiva)†

Captive parrots show a high incidence of obesity and other metabolic disorders due to the consumption of unbalanced diets. Therefore, this study evaluated the digestibility and metabolic effects of transitioning blue-fronted amazons from a high fat diet (sunflower seeds) to processed diets with three degrees of starch gelatinization (SG). The same feed formulation was processed to obtain pelletized feed (PEL) at 27.1% SG; low-cooked extruded feed (EXT_L ) at 81.6% SG; and high-cooked extruded feed (EXT_H ) at 98.5% SG. Thirty adult parrots were fed sunflower seeds for 90 days, then were distributed in a completely randomized design with 10 repetitions per treatment, and fed one of the three prepared diets for 160 days. Feed palatability, apparent digestibility, excreta concentrations of volatile fatty acids, lactate and ammonia, initial and final radiographic examinations, blood cell counts and glucose, triglycerides, cholesterol, total protein, albumin, aspartate aminotransferase (AST) and uric acid levels were evaluated. The data were analysed by an analysis of variance and compared by Tukey's test (p < 0.05). Sunflower seed was more digestible than processed feeds (p < 0.05). Diet processing interfered with fat and starch digestibility (p < 0.001), being higher in the PEL than in the EXT_H and EXT_L respectively. Transitioning from sunflower seeds to balanced diets reduced serum glucose, triglycerides, cholesterol and AST (p < 0.05) and increased red blood cell, haemoglobin, lymphocyte, monocyte and leucocyte counts (p < 0.01). Radiographs indicated a decreased hourglass (p = 0.015) and a reduced heart-liver ratio after ingesting the processed feeds (p < 0.05). Feed processing did not affect blood cell counts, serum biochemistry or radiographic examinations. In conclusion, parrots preferred the extruded diet and did not require an extensive SG to properly digest the feed. Consuming the processed diets improved the birds' metabolism and health.