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.

Retrospective Analysis of Cataract Formation and Nutritional Etiology in a Managed Collection of Parakeet Auklets (Aethia psittacula).

The parakeet auklet (Aethia psittacula) is a piscivorous seabird with a natural diet of various invertebrate and teleost species, which is challenging to replicate in a managed collection. A high prevalence of early onset cataracts was observed in a managed collection of parakeet auklets at the North Carolina Zoo (Asheboro, NC, USA), which was hypothesized to be related to inappropriate vitamin A and E levels. From 1994 to 2002, these parakeet auklets were offered dietary supplementation comprising Vita-Zu small bird tablets. In June 2002, the birds were transitioned to only Thiamin-E paste (vitamin E and thiamin only). Plasma samples were collected from birds with and without cataracts from 1998 to 2005 and submitted for vitamin A (retinol) and vitamin E (α-tocopherol) analysis. Food items comprising the birds' diet were also evaluated for vitamin content. This information was combined with clinical and necropsy data from medical records from 1994 to 2015. A total of 78% of birds (39/50) developed cataracts, with a median age of onset of 7 years (range, 2-12 years). Cataracts ranged from incipient to hypermature during both routine ophthalmic examinations and postmortem evaluations. The median (range) of plasma retinol and α-tocopherol values were 1.99 µg/mL (0.20-6.68 µg/mL) and 15.39 µg/mL (3.40-96.27 µg/mL), respectively. There were no significant differences in plasma concentrations of vitamins based on the animals' sex, origin, presence of cataracts, or administered vitamin supplementation product. No other etiologies for cataract development were identified in the population. Further research in free-ranging parakeet auklet nutrition and cataract occurrence is warranted for continued species collection management.

A comparison of nutritional value of native and alien food plants for a critically endangered island flying-fox.

Habitat loss and alteration are two of the biggest threats facing insular flying-foxes. Altered habitats are often re-vegetated with introduced or domestic plant species on which flying-foxes may forage. However, these alien food plants may not meet the nutritional requirements of flying-foxes. The critically endangered Christmas Island flying-fox (CIFF; Pteropus natalis) is subject to habitat alteration and the introduction of alien food plants, and therefore is a good model species to evaluate the potential impact of alien plant species on insular flying-foxes. In this study, we evaluated nutritional content of native food plants to determine how flying-foxes historically met their nutritional requirements. Furthermore, we compared the nutritional content of native and alien fruits to predict possible impacts of alien plants on insular flying-foxes. Native and alien fruits and flowers, and native foliage (leaves, petals, and petioles) commonly consumed by the CIFF were collected and evaluated for soluble sugars, crude protein, non-fiber carbohydrates, and nine minerals. Evaluation of native food plants suggests that flying-foxes meet energy requirements by consuming fruit and nectar. However, fruit and nectar are low in protein and essential minerals required for demanding life periods; therefore, flying-foxes likely supplement their diets with pollen and foliage. Thus, flying-foxes require a diverse array of plants to meet their nutritional requirements. Compared to native fruits, alien fruits contained significantly higher non-fiber carbohydrates, and this may provide an important energy source, particularly from species that bear fruit year-round. Median mineral concentrations in alien fruit species, however, were deficient compared to native fruits, suggesting major (or even seasonal) shifts in the proportion of alien species in the CIFF diet could lead to nutritional imbalances. This study confirms the need to quantify nutritional parameters in addition to feeding ecology when evaluating habitat quality to inform conservation actions that can be applied both locally and globally.

Effect of dietary carotenoids on vitamin A status and skin pigmentation in false tomato frogs (Dyscophus guineti).

Several species in captivity develop nutritional diseases including vitamin A deficiency; cases of this disease have been documented in amphibians, which may be linked to an insectivorous diet lacking in vitamin A or carotenoids. Adults and young of Dyscophus guineti were fed three diets over 9 weeks to evaluate effects on carotenoids and vitamin A status and skin pigmentation. Feeder crickets were either supplemented with soy oil (control, CON), soy oil enriched with ß-carotene (BC) or mixed carotenoids (MIX) by direct injection of known dosages. Vitamin A from feeder crickets (measured as retinol) was higher in insects supplemented with both BC and MIX; (P=0.0001) and plasma retinol concentrations were significantly higher in frogs fed MIX (P<0.02). Results suggest that both false tomato frogs and feeder crickets could receive some provitamin A activity through consumption of diets supplemented with ß-carotene, and xanthophylls like lutein and zeaxanthin. Pigmentation was evaluated weekly through the use of visual color charts, as well as quantitatively using a hand-held spectrophotometer. MIX diets had a significant effect on skin color values (P<0.0001), as well as on lightness (P=0.0005) and hue (P=0.0022). Results indicated that frogs fed with BC changed to yellower colors, and frogs fed with MIX changed to oranger colors. Visual color chart observations also scored significantly different between CON and MIX diets (P<0.05); the animals fed MIX also appeared oranger according to the qualitative observations. Dietary supplements with carotenoids resulted in color changes and higher circulating retinol concentrations in false tomato frogs. These pigments may provide provitamin A activity in diets, thus may support improved nutrition and health of captive-fed insectivorous amphibians.

Supplemental iodine as a key to reproduction in pandas?

Pandas are endemic to iodine-poor environments and appear to be specialized for a goitrogenic staple diet. In particular, the importance of thiocyanate in bamboos might possibly have been overlooked in captive breeding programs. Although excreted in urine, thiocyanate first antagonizes absorption of iodine by the thyroid (of parent, fetus and suckling juveniles) and the mammary glands. In livestock and humans, subclinical deficiency of iodine is known to result in reproductive problems (including retardation of the fetus and suckling infant) even where the mother appears to be unaffected beyond slight hyperplasia of the thyroid and subtle hypothyroidism as reflected by levels of thyroid hormones. We suggest that the possibilities of iodine deficiency or excess should be carefully considered wherever the reproductive rates of pandas are unsatisfactory.

Diet manipulation as treatment for elevated serum iron parameters in captive raggiana bird of paradise (Paradisaea raggiana).

Elevated serum iron parameters were lowered through dietary manipulation in captive Raggiana bird of paradise (Paradisaea raggiana). Study birds were part of a captive breeding program consisting of two males and one female, captive born, 3.5-9 yr of age. Serum iron, total iron binding capacity (TIBC), percentage saturation, body weight, albumin, aspartate aminotransferase, and hematocrit were monitored at regular intervals for 2.5 yr. Routine diet consisted of a variety of fruits, vegetables, a multivitamin supplement, and a commercial low iron avian pellet, with a dietary iron content of 55 mg/kg (dry matter basis) or 1.12 mg iron/bird/day. Dietary treatment involved removal of the commercial avian pellet for 30 days at 6-to 12-mo intervals, resulting in an iron content of 42 mg/kg (dry matter basis) or 0.64 mg iron/bird/day. Average serum iron and TIBC were decreased by 75% (TIBC) to 80% (serum iron) ofpretreatment values after one 30-day treatment. Average iron saturation levels were lowered by 10% of pretreatment values after one 30-day treatment. Average hematocrit, albumin, aspartate aminotransferase, and body weight remained unchanged. No adverse effects were noted through the 2.5-yr evaluation period, and breeding behavior was undisturbed. Periodic removal of low iron commercial pellets in the diet of captive bird of paradise is a safe and effective method for lowering serum iron values without need for handling. Periodic application of this technique may be useful as a preventive tool to maintain appropriate serum iron values in avian species susceptible to iron storage disease.

Feeding behavior and nutrition of the sugar glider (Petaurus breviceps).

Despite the sugar glider's popularity as a pet and a long-term history of captive management in zoologic institutions, little is known concerning their specific nutritional requirements, apart from low basal energy and protein needs. Sugar gliders feed on plant and insect exudates-saps, gums, nectar, manna, honeydew, and lerp-as energy sources and rely on pollen and arthropods for dietary protein. Captive diets based on nutritionally balanced, commercially available products developed for other species, with added produce, have been fed successfully in zoo and private glider colonies, but these diets may not promote optimal gut function or feeding behaviors. Diets commonly fed by private owners were examined in feeding trials and were found to be highly digestible, but contained excess protein that was likely imbalanced in amino acids, as well as in calcium and phosphorus, because of improper supplementation. Suggestions are outlined for areas of relevant research to improve nutritional husbandry of sugar gliders.

Diet composition and blood values of captive cheetahs (Acinonyx jubatus) fed either supplemented meat or commercial food preparations.

Nutrition most certainly affects health and may play a role in the etiology of growth and reproductive problems in captive cheetah (Acinonyxjubatus) populations. The objective of our research was to examine nutritional differences between two dietary regimens and quantify their physiologic effects on cheetahs held in captivity. Twelve cheetahs were randomly assigned to either a commercial diet (COM) or a supplemented meat diet (SMD) group. These cats were physically examined and had blood samples taken three times over the course of a year. Representative samples of COM and four separate components of the SMD treatment were analyzed over the same time frame for proximate nutrient composition, digestibility, and concentrations of taurine, fat-soluble vitamins, and selected minerals. Concentrations of fat, vitamins A and E, Se, Fe, Cu, Na, and Mn were significantly higher in COM compared with those in SMD samples, with the exception of fat content in turkey. Mg content was lower in COM than in SMD; other nutrients did not differ. Mean concentrations of vitamins A and E in COM were markedly higher than in SMD samples (408,140 vs. 29,696 IU/kg dry matter [DM] and 431 vs. 48 IU/kg DM, respectively) and varied dramatically between sampling periods. Percent crude protein and protein-to-fat ratios were high for SMD compared with either whole prey-based or commercial food preparations. Blood urea nitrogen and serum creatinine levels were above normal reference means for domestic cats. Plasma concentrations of vitamins A, D, and E were significantly higher in COM-fed than in SMD-fed cheetahs. Both plasma retinol and tocopherol levels were almost three times higher in COM-fed cats (1.26 +/- 0.06 vs. 0.53 +/- 0.03 microg/ml and 17.5 +/- 0.7 vs. 6.4 +/- 0.02 microg/ml, respectively) and exceeded the normal ranges expected for domestic felids. Significant differences between male and female cheetahs were found for plasma concentrations of vitamin E, Se, and Fe after allowing for effects of diet and time of collection. Excess fat-soluble dietary vitamins can result in direct toxicities as well as nutrient antagonisms and may be linked to reproductive and health issues in captive cheetahs. The high protein levels found in SMD may be linked to chronic renal disease, which was detected in some of these cheetahs.

Fat soluble vitamins in blood and tissues of free-ranging and captive rhinoceros.

Several disease syndromes in captive rhinoceroses have been linked to low vitamin status. Blood samples from captive and free-ranging black (Diceros bicornis) and white rhinoceros (Ceratotherium simum) and tissue samples of captive individuals from four rhinoceros species were analysed for vitamins A and E. Circulating vitamin A levels measured as retinol for free-ranging versus captive black and white rhinoceros were 0.04 (+/- 0.03 SD) vs. 0.08 (+/- 0.08) and 0.07 (+/- 0.04) vs. 0.06 (+/- 0.02) microgram/ml, respectively. Circulating vitamin E levels measured as alpha-tocopherol were 0.58 (+/- 0.30) vs. 0.84 (+/- 0.96) and 0.62 (+/- 0.48) vs. 0.77 (+/- 0.32) microgram/ml, respectively. In contrast to earlier findings, there was no significant difference in vitamin E concentration between captive and free-ranging black rhinoceros. When the samples of captive black rhinoceros were grouped into those taken before 1990 and after 1990, however, those collected before 1990 had significantly lower (P < 0.001) vitamin E levels (0.46 +/- 0.83 microgram/ml) and those collected in 1990 or later significantly higher (P < 0.001) vitamin E levels (1.03 +/- 1.04 micrograms/ml) than the captive population as a whole. This is probably due to increased dietary supplementation. There were significant differences in circulating vitamin concentrations in black rhinoceroses from different regions in the wild. Serum 25-hydroxy (OH) vitamin D3 averaged 55.7 ng/ml in free-ranging rhinoceroses; no carotenoids were detected in any blood samples. Captive black and white rhinoceroses appear to be adequately supplemented in vitamin A and E. Captive Indian rhinoceroses (Rhinoceros unicornis) had significantly lower vitamin A concentrations in blood (P < 0.001) and higher vitamin A concentrations in liver tissue samples (P < 0.001) than other rhinoceros species. Equine requirements are not recommended as a model for rhinoceros vitamin requirements.