Milk composition in free-ranging polar bears (Ursus maritimus) as a model for captive rearing milk formula

Gail E. Hedberg, Andrew E. Derocher, Magnus Andersen, Quinton Rogers, Edward J. Depeters, Bo Lönnerdal, Lisa Mazzaro, Russell W. Chesney, Bruce Hollis

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


The goals of this study were to have an improved understanding of milk composition and to help create a suitable milk formula for cubs raised in captivity. Milk samples were evaluated for fat, fatty acids, carbohydrate, vitamin D 3, 25(OH)D 3, vitamin A (retinol), vitamin E (α-tocopherol), protein, and amino acids. Total lipids in milk did not differ for cubs (mean ± SEM = 26.60 ± 1.88g/100ml vs. yearlings 27.80 ± 2.20g/100ml). Milk lipids were of 23.6% saturated fatty acid for cubs and 22.4% for yearlings. Milk consumed by cubs and yearlings contained 43.8 and 42.0% mono-unsaturated fatty acids and 23.4 and 21.9% polyunsaturated fatty acids, respectively. Carbohydrate content was higher in milk for cubs (4.60 ± 0.64g/100ml) than for yearlings (2.60 ± 0.40g/100ml). Vitamin D 3 concentration of milk was 18.40 ± 5.00ng/ml in early lactation compared with 7.60 ± 2.00ng/ml for mid-lactation. 25(OH)D 3 was lower in milk consumed by cubs (162.00 ± 6.70pg/ml) than in milk consumed by yearlings (205.00 ± 45.70pg/ml). Vitamin A concentrations were 0.06 ± 0.01 and 0.03 ± 0.01μg/ml for cubs and yearlings, respectively. Vitamin E was higher in milk consumed by cubs (20.16 ± 4.46μg/ml) than by yearlings (7.30 ± 1.50μg/ml). Protein content did not differ in milk available to cubs (11.40 ± 0.80g/100ml compared with milk for yearlings 11.80 ± 0.40g/100ml). Taurine was the most abundant free amino acid at 3,165.90 ± 192.90nmol/ml (0.04% as fed basis).

Original languageEnglish (US)
Pages (from-to)550-565
Number of pages16
JournalZoo Biology
Issue number5
StatePublished - Sep 2011


  • Amino acids bears
  • Fatty acids hand-rearing
  • Lactation
  • Maternal milk
  • Vitamin A
  • Vitamin D
  • Vitamin E

ASJC Scopus subject areas

  • Animal Science and Zoology


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