International Giant Otter Studbook Husbandry and Management

The gradual change-over from feeding milk replacer formulas to feeding a total fish diet is
called “weaning”. More research needs to be conducted to determine the most optimal age to
start a slow gradual weaning process. The information available indicates that a giant otter cub
should be around at least 2 ½ to 4 months old when fish is first introduced into its diet and the
weaning process is begun. The age at which each cub will first accept fish will vary from
individual to individual, although it seems that milk formula should be given to fulfill 100% of
the giant otter cub’s nutritional needs until it reaches around at least 2 ½ months of age. Not
fulfilling 100% of the cub’s nutritional needs with a milk formula before this age or waiting too
long to begin the weaning process may cause health problems. When the weaning process was
started with cubs that were around approx. 2 ½ and 3 or 4 months old, those cubs were
successfully reared. Many wild-born orphaned cubs reared at the institutions that used this
method have been successfully reared (Lazzarini 1998 pers. comm.; McTurk/Duplaix pers.
comm. 2004). Note: the ages of the wild-born animals were estimated. At Hagenbecks
Tierpark (Germany) giant otter cubs, at approximately 8 weeks old, mouthed and played with
fish that the mother brought to them; although they only first started swallowing solid fish at 70
days of age (10 weeks old) (Hagenbeck and Wünnemann 1992). Later reports explain that two
captive-born handreared cubs at Hagenbecks ingested solid food at 3 months old, although it
was found that they could not digest the fish properly when they were this age. “The feces
contained a lot of undigested fat and protein and the enzyme level of chymotrypsin was much
lower than in adult animals” (Wünnemann 1995 b ). Giant otter cubs are dependent on the
mother’s milk for at least the first 4 months of life (Wünnemann 1995). The cubs continued
nursing mother’s milk when they were around 6 1/2 months old, although only insignificant
amounts were obtained and it provided little nutritional value. The weaning process can occur
over a varying time period until the cubs choose to reject the milk formula (Duplaix/McTurk &
Wünnemann pers. comms. 2004). Cubs may choose to reject milk formula from one, a couple,
a few, or even several months after accepting fish within their diet for the first time (pers.
comms. of the handrearers listed within this manual). Sometimes they may also reject milk
formula from 2 to 3 weeks after they start to eat fish within their diet. Caution must be taken
although, as the offering of milk formula should not be eliminated or reduced in amount too
soon or problems may result. See Chapter 5 Section 12 for details.
Reports indicate that giant otters do not require milk to meet their basic nutritional needs when
they are at the age of around 6 ½ months and older (note: this does not mean that their needs can
not be met at an earlier age; see the paragraph above). At one institution, some handreared
otters although have been reported to drink some supplemental milk formula (i.e. in addition to
their fish diet), even up to 10 months of age and they were reported to be successfully reared
(Duplaix/McTurk, pers. comm. 2004). Handrearers should although take care that otters wean
themselves fully of all milk formula within a reasonable time period. It seems that by at least 6
½ months of age, and up to an age that does not exceed approx. 10 months [based on the
outcome of the handreared otters just mentioned above], the cub should be eating a total fish
diet and should no longer be drinking any milk formula (Duplaix/McTurk & Wünnemann pers.
comms. 2004). Scientific research on the meeting of nutritional needs of handreared giant otters
at various ages should be conducted to establish scientific guidelines for the weaning process.
The physical and behavioral development of each wild orphaned and captive-born individual
handreared should be thoroughly documented and studied. Field researchers are currently
requesting information on cub body weight, body length, and age correlation and behavioral and
physical ability development in order to use as a reference source for wild populations. A
complete age - weight - length growth curve needs to be developed for handreared giant otters.
I.e. measurements should be taken from the earliest age to the latest age that is possible. (See
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