Analyses of Diet and Serum Mineral Concentrations in African Elephants (Loxodonta africana) Housed at the NC Zoo

Citation

Wood J, Koutsos E, Kendall C, Minter L, McComb A, Tollefson T, Heugten K. 2017. Analyses of Diet and Serum Mineral Concentrations in African Elephants (Loxodonta africana) Housed at the NC Zoo. In Ward A, Coslik A, Brooks M Eds. Proceedings of the Twelfth Conference on Zoo and Wildlife Nutrition, Zoo and Wildlife Nutrition Foundation and AZA Nutrition Advisory Group, Frisco, TX.

Abstract

Elephants in human care (Loxodonta africana) are often over conditioned. Consequently, many zoos aim for reduced caloric intake and increased activity levels. Diets containing higher dietary browse and forage percentages with lower inclusion of pelleted components may stimulate increased foraging behavior. However, feeding increased browse with unknown nutrient profiles while decreasing pelleted nutritionally complete feed could prove problematic with respect to nutritional requirements despite stimulating wanted behaviors. The NC Zoo decided to feed a new grain-free supplement (Hay Enhancer^TM, Mazuri®) while increasing their daily browse offerings and eliminating the prior nutritionally complete feed. There were two goals for the current research: 1) To determine the percentage and complete mineral profile of all browse species consumed by the six NC Zoo elephants from February 2016 to January 2017 and 2) To determine if the new total diet meets recommended elephant mineral requirements by assessing both diet and circulating serum mineral concentrations. Individual elephant weights and blood samples were collected monthly. Every six weeks, a four-day complete diet weigh in and out was completed for all offered browse species, produce, and hay to analyze for nutrients. Estimated daily food intakes ranged from 61-72 kg, similar to wild African elephant consumption data. Results show 39 browse species were fed between February 2016 and January 2017 and browse consumption ranged from 5-17 kg per elephant daily, which though a minor component of the overall diet represents an increase in the percentage of dietary browse offered since 2015. Browse was analyzed for minerals (Ca, Cl, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Se, and Zn). The browse species varied dramatically in mineral content due to season and species. When complete diets were analyzed for each elephant, the intake of several minerals appear marginal or of concern within the analyzed diets. Na was deficient in both summer and winter diets (0.04 %) compared to the current recommended value (0.10 %). Cu (10.5- 10.8 ppm) and Zn (43 – 47 ppm) were marginally sufficient compared to recommended intake (10 ppm, 40 ppm) for African elephants. Fe (322 – 985 ppm) and Mn intake (50 – 68 ppm) both highly exceeded recommended intake values (50 ppm, 40 ppm). Even with the removal of the Mazuri supplement for data comparisons, Fe and Mn remain high. These results indicate that specific browse species should be avoided for long term use within NC elephant diets due to mineral profiles inconsistent with species nutritional needs. Serum was analyzed for the minerals: Ca, Cl, Co, Cu, Fe, K, Mg, Mn, Mo, Na, Na/K ratio, P, Se, and Zn. Serum mineral ranges for Ca, Cl, K, Na, Na/K ratio, and Zn were within reference ranges for African elephants.  Magnesium (2.2 – 3.0 mg/dL) tended towards the upper limit (0.8 – 3.0 mg/dL). Phosphorus (3.8 – 5.9 mg/dL) was above the reference range (1.07 -2.3 mg/dL) and the range for iron (59 – 188 ug/mL) often surpassed the reference range (8.4 – 151.9 ug/mL). Copper (0.77 – 1.23 ug/mL) often fell below the reference range (0.86 – 1.34 ug/mL). The data generated will enable the NC Zoo and other zoos within the region to better incorporate appropriate browse species into animal diets across seasons, and ensure that nutrient intakes are appropriate based on current knowledge.

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