Purina Mills, Inc., St. Louis, MO, USA
With increasing awareness of the precarious status of natural fish populations, the need for renewable and
sustainable foods that can be integrated into the diets for captive marine birds and mammals becomes more critical.
To achieve an appropriate diet replacement for fish, that food item must be:
2. Nutritionally adequate
3. Cost effective
4. Readily available
To date, a number of key milestones have been reached in developing a replacement diet, however,
additional research and refinement will be required before a final product is ready for widespread distribution.
A gel type feed has been developed which allows a flexible, smooth-surfaced product which can be produced in a
variety of sizes suitable for the target species. This product has been demonstrated as palatable across multiple species,
including penguins, seals and sea lions. Most recently, as part of a preliminary study, the product has also been accepted by
Exact nutrient requirements for these fish-eating species have not yet been adequately quantified. As a result,
this food has been formulated to closely match the nutrient profile of live fish. A limited set of feeding trials conducted with
mature gentoo, rockhopper and king penguins indicate the product delivers adequate nutrition to maintain body weight and condition
for 10 mo. Additionally, from 60 days to fledge, king penguin chicks hand-fed the gel type feed grew at rates comparable to those
hand-fed a diet of fish. Finally, California sea lions and seals have been maintained with this diet as a supplement to the
traditional fish diet for nearly 2 yr.
During the development period, a number of unanticipated benefits of this type of diet technology have been
discovered. The first of which are the benefits to animal health. During manufacturing the product goes through a pasteurization
process that significantly reduces any bacterial load. The second benefit is the flexibility of the final nutrient formulation. For
the first time, complete diets can be formulated for fish-eating species to study various or specific nutritional parameters
through the manipulation of the feed.
Finally, the scope of species that may benefit from this technology reaches far beyond those that have been
tested to date.
At present, the diet has a cost that is comparable to the market price of high quality fish. Because the major
components used in producing the diet are commonly available food industry ingredients, the problematic or seasonal availability of
this product should not be a concern.