Elephants Elephants - Wildpro - Twycross Zoo

Vitamin E conversion factors
Vitamin E supplements may be labelled d for natural and dl for synthetic.
Commercially there is no truly ‘natural’ tocopherol product available since even the d
α-tocopherol commercial products are obtained from the original raw material only
after several chemical processing steps. Hence it should really be referred to as
‘naturally-derived’. The international unit (IU) is the standard of vitamin E activity
and is the same regardless of source, although conversion factors for d & dl
tocopherol are different:
1 IU = 1.00 mg dl α-tocopherol acetate (synthetic)
Requirements & recommendations
While the production goals may be very different, comparative data from
domestic livestock are used since requirements for most zoo species have not
been established. Perissodactyls all possess a digestive anatomy with an
enlarged hindgut for plant fermentation, hence horses are likely physiological
models for exotic equids and other perissodactyl groups (tapirs and rhinos).
Elephants have similar gut morphology and are included within this group
for comparative purposes. Exotic ruminants (artiodactyls) include all
antelope, deer, giraffe, mouse deer and camelid families. Though
considerable gastrointestinal variation exists across the taxa, all rely on foregut
fermentation thus cattle and sheep are the best physiological models available.
Vitamin E requirements for domestic species range from 5-50 IU/kg dry diet
and most commercially available compound feeds are fortified accordingly
(~50IU/kg dry matter). In response to an increasing observation of vitamin E
deficiencies in many captive wild animals, recent recommendations for these
species are considerably higher, around 100-200 IU per kg dry diet. Green
forage and other leafy material are good natural sources of α-tocopherol;
young grass being a better source than mature herbage and lucerne being
especially rich. Leaves may contain 20 times as much vitamin E as the stems.
Yet losses during haymaking can be as high as 90%, thus captive herbivores
with limited access to fresh herbage may require supplementation.
Vitamin E supplements
= 0.67 mg d α-tocopherol (natural/naturally derived)
Unless stated otherwise, dl α-tocopherol acetate has been taken as the active
ingredient of supplements named in this document since it is the most commonly
used form commercially.
In the UK a number of products are used to supplement vitamin E for captive
herbivores. Vitamin E form and potency of selected products (including one
in 2 strengths) are compared in Table 1.
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