FISH NUTRITION
449
Although it was not at this time appreciated that a nutritional
deficiency was the cause of the diseases mentioned, doubt was being
cast on the view that germs were the causative agent.
The discovery, towards the end of the last century, that similar
diseases could be induced in domestic animals led to controlled
experimental studies in which the nutritional origin of these diseases
was made absolutely apparent. Early in the present century the
search for essential constituents in food had begun, using refined diets.
In 1912 the classic paper on “ accessory growth factors ” by Hopkins
appeared and the “vitamine theory” was propounded by Funk.
When, later, it became clear that not all “vitamines” contained
amine groups or even nitrogen the term was modified to vitamin.
Modern definitions of the term vitamin generally include the
following points :
(i) the organic nature of the substances concerned;
(ii) the presence of these substances in natural food in extremely
small amounts ;
(iii) these substances are distinct from the major components of
food, i.e. protein, carbohydrate and fat ;
(iv) animals have an absolute dietary requirement for them ; they
cannot themselves synthesize the compounds concerned ;
(v) speciiic deficiency diseases occur when these compounds are
totally absent from the diet.
Research into the vitamin requirements of fish has proceeded with
increasing vigour. The early work leading to the evolution of a vitamin
test diet has been admirably traced by Halver (1969). A suitable test
diet, first developed by Wolfe (1951), was considerably modified and
improved by Halver (1957). Halver’s modified test diet has formed the
basis of much modern research on vitamin requirements and deficiency
diseases in fish.
This diet contained sixteen vitamins and chinook salmon fingerlings were grown on it for eighteen weeks. At the end of this time tissues
were examined for both gross and histological changes and shown to be
normal. Erythrocyte counts and haemoglobin values were also
normal. Thereafter each vitamin was in turn deleted singly from the
diet and the fish reared for a time period sufficient to demonstrate the
essentiality or otherwise of the vitamin. Deficiency syndromes were
established for each essential vitamin and dose/response curves were
used to quantitate the daily requirements for vitamins.
Halver’s methods have been applied to other species and
descriptions of deficiency syndromes are becoming more common. A
449
Although it was not at this time appreciated that a nutritional
deficiency was the cause of the diseases mentioned, doubt was being
cast on the view that germs were the causative agent.
The discovery, towards the end of the last century, that similar
diseases could be induced in domestic animals led to controlled
experimental studies in which the nutritional origin of these diseases
was made absolutely apparent. Early in the present century the
search for essential constituents in food had begun, using refined diets.
In 1912 the classic paper on “ accessory growth factors ” by Hopkins
appeared and the “vitamine theory” was propounded by Funk.
When, later, it became clear that not all “vitamines” contained
amine groups or even nitrogen the term was modified to vitamin.
Modern definitions of the term vitamin generally include the
following points :
(i) the organic nature of the substances concerned;
(ii) the presence of these substances in natural food in extremely
small amounts ;
(iii) these substances are distinct from the major components of
food, i.e. protein, carbohydrate and fat ;
(iv) animals have an absolute dietary requirement for them ; they
cannot themselves synthesize the compounds concerned ;
(v) speciiic deficiency diseases occur when these compounds are
totally absent from the diet.
Research into the vitamin requirements of fish has proceeded with
increasing vigour. The early work leading to the evolution of a vitamin
test diet has been admirably traced by Halver (1969). A suitable test
diet, first developed by Wolfe (1951), was considerably modified and
improved by Halver (1957). Halver’s modified test diet has formed the
basis of much modern research on vitamin requirements and deficiency
diseases in fish.
This diet contained sixteen vitamins and chinook salmon fingerlings were grown on it for eighteen weeks. At the end of this time tissues
were examined for both gross and histological changes and shown to be
normal. Erythrocyte counts and haemoglobin values were also
normal. Thereafter each vitamin was in turn deleted singly from the
diet and the fish reared for a time period sufficient to demonstrate the
essentiality or otherwise of the vitamin. Deficiency syndromes were
established for each essential vitamin and dose/response curves were
used to quantitate the daily requirements for vitamins.
Halver’s methods have been applied to other species and
descriptions of deficiency syndromes are becoming more common. A