 Reference Base  Plasma vitamin E response in two black rhinoceroses follo... |
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| Location: |
World |
| Subject: |
Physiology |
| Species: |
All Rhino Species |
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Captive black rhinoceroses (Diceros bicornis) examined at several zoos have been found to have very low plasma vitamin E concentrations (Dierenfeld and others 1988, Ghembremeskel and others 1988, Lewis and Kirkwood 1990). It has been suggested that this may be a factor in the aetiology of the haemolytic anaemia that is an important cause of mortality in these animals (Miller and others 1986). Dietary supplementation with high doses of dl- -tocopherol acetate or with dl- -tocopherol have been found to have little effect on plasma vitamin E levels (Papas and others 1989, Lewis and Kirkwood 1990).
Recently, Papas and others (1989) have reported the reversal of vitamin E deficiency in several captive Asian and African elephants (Elephas maximum and Loxodonta africanus) at the Denver Zoo, and two black rhinoceroses at the Miami Metro Zoo, following dietary supplementation with d- -tocopheryl polyethylene glycol 1000 succinate (TPGS; Eastman Chemical, Kingsport, Tennessee). These authors found that plasma -tocopherol concentrations in the rhinoceroses rose from baseline levels of 0.2 to 0.4 mg/litre to about 2.4 mg/litre after provision of TPGS at 2100 iu per day for 14 days. This communication reports on a comparable and marked plasma response to oral TPGS in two black rhinoceroses at the Zoological Society of London.
The animals treated with TPGS were adult males of similar size. The first, 'Jasper', was given TPGS once daily with food at a dose of about 12,000 iu per day and the second, 'Basha', was given about 7500 iu per day (approximately 8 and 5 iu/kg bodyweight daily, respectively). The TPGS, which is a waXy solid, was prepared by melting 20 g samples at above 40?C. When melted the liquid was poured slowly into 100 ml boiling water and stirred. On cooling the resulting clear fluid contained about 7000 iu/100 ml TPGS. The doses were provided by soaking the supplement into bread. Both animals were sufficiently tractable to allow blood samples to be regularly collected from their medial carpal veins without chemical or physical restraint. After withdrawal using a 19 gauge 1 inch needle, these samples were immediately transferred to tubes containing heparin for subsequent vitamin E and general biochemical analyses, and tubes containing EDTA for haematology. The plasma was separated by centrifugation and stored at -20?C before dispatch for assay. The samples from Jasper were analysed for vitamin E content by the nutritional biochemistry group at the Institute of Zoology (Ghembremeskel and Williams 1988), and those from Basha were analysed at the Shrewsbury MAFF Veterinary Investigation Centre.
The results are shown in Fig 1. Jasper's plasma vitamin E concentration increased from 0.6 mg/litre before TPGS supplementation to 3.9 mg/litre after 13 days. In Basha the plasma concentration increased from less than 0,1 mg/litre to 1,0 mg/litre after 14 days. The explanation for the difference in baseline levels is not clear but both animals showed a prompt surge in plasma vitamin E levels when TPGS supplementation began, to a greater than six-fold increase above their baseline levels. Samples collected from Jasper after supplementation ceased showed a quite rapid decline in plasma levels towards the baseline. Haematological parameters remained within normal limits throughout the period of study in both animals.
These results support the findings of Papas and others (1989) that TPGS is an effective source of vitamin E for black rhinoceros.
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