Analysis of nectar replacement products and a case of iron toxicosis in hummingbirds


Frederick H, Dierenfeld E, Irlbeck N, Dial S. 2003. Analysis of nectar replacement products and a case of iron toxicosis in hummingbirds. In Ward A, Brooks M, Maslanka M, Eds. Proceedings of the Fifth Conference on Zoo and Wildlife Nutrition, AZA Nutrition Advisory Group, Minneapolis, MN.


Twenty-five of 26 hummingbirds (Trochilidae) from 7 species previously maintained in an aviary on a commercial nectar substitute for 13 years, died over 3-month period. Gross necropsy was inconclusive; however, staining of liver and intestinal tissue showed high levels of Fe deposition. Analysis of separate bags (n=9) of the nectar product, with identical lot numbers, showed variation in Fe content from 26 to 886 mg/kg, compared to a manufacturer’s specification of 40 mg/kg. A low Fe (20 mg/kg) diet was formulated for reintroduction of birds to the aviary. Samples of nectar replacement products (n=14 from 9 manufacturers) were analyzed for an array of nutrients including proximate composition, fat-soluble vitamins A and E, and minerals. Wide ranges in composition were detected among products, with no consistent variability (i.e. products with high values for one nutrient didn’t necessarily have high values for any others). Crude protein ranged from 1.7 to 23.1, crude fat ranged from 1.9 to 12.8, CHO content (calculated) from 37.9 to 75.9, and ash, 0.67 to 7.0 (all % dry matter, DM, basis). Ca and P (% DM) varied 10 to 220-fold, from low concentrations (0.12 and 0.003, respectively), to highs of 1.24 and 0.67. Ca:P ratios ranged from 0.75:1 to 154:1. Vitamins A and E (IU/g) varied from lows of 0.33 and 0.005, respectively, to highs of 4,932 and 2.71, respectively. Fe content varied almost 800-fold, from 4.4 to 3,485 mg/kg DM. These analyses, in conjunction with the reported pathology, suggest a need to review Fe levels in commercial replacement products used in captive feeding programs for feeding nectarivorous species.

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