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4. DERANGEMENTS IN MINERAL NUTRITION


4.1 Dietary essential mineral deficiency
4.2 Dietary mineral toxicity


4.1 Dietary essential mineral deficiency

The following gross anatomical deficiency signs have been reported in juvenile fish fed experimental diets lacking in one or more essential minerals:

Element/Fish Species

Deficiency signs 1/

PHOSPHORUS

C. carpio

Reduced growth, poor food conversion efficiency (1,2); bone demineralization, skeletal deformity, abnormal calcification of ribs and the soft rays of pectoral fin (1); cranial deformity (1,3); increased visceral fat (4)

I. punctatus

Reduced growth, poor food conversion efficiency (5); bone demineralization (5,6)

P. major

Reduced growth, poor food conversion efficiency, bone demineralization, increased muscle, liver and vertebrae lipid content (7); curved and enlarged spongy vertebrae (8); decreased liver glycogen (9)

A. japonica

Anorexia, reduced growth (10)

S. gairdneri

Reduced growth, poor food conversion efficiency, bone demineralization (13,14)

S. salar

Reduced growth, poor food conversion efficiency, bone demineralization (13,14)

CALCIUM

I. punctatus

Reduced growth, low carcass ash, Ca and P content (fed vitamin D deficient diet, 6)

S. gairdneri

Anorexia, poor growth and food conversion efficiency (15)

A. japonica

Anorexia, poor growth and food conversion efficiency (16)

P. major

Anorexia, poor growth and food conversion efficiency (17)

MAGNESIUM

C. carpio

Reduced growth (11,18); sluggishness, anorexia, convulsions, high mortality, reduced bone magnesium content (11); cataracts (18)

I. punctatus

Anorexia, reduced growth, sluggishness, muscle flacidity, high mortality, depressed Mg content in body and blood serum/bone (19)

A. japonica

Anorexia, reduced growth (20)

S. gairdneri

Reduced growth (21-24); anorexia (22,23); cataracts (25); sluggishness, calcinosis of kidney (21,22); increased mortality, vertebral curvature, degeneration of muscle fibres and epithelial cells of pyloric caecae and gill filaments (23); reduced bone ash, Mg and elevated Ca content (24)

IRON

Hypochromic microcytic anaemia (C. carpio-26; P. major-27; Salvelinus fontinalis-28; A. japonica-20)

ZINC

I. punctatus

Reduced growth and appetite, depressed bone Ca and Zn content, and serum Zn (29)

C. carpio

Reduced growth (30,18); cataracts (18); loss of appetite, high mortality, erosion of fins and skin, elevated tissue concentration of Fe and Cu in intestine and hepatopancreas (30)

S. gairdneri

Reduced growth (25,31,32); increased morality (31,32); cataracts (25,31); short body dwarfism (25); fin erosion (31)

MANGANESE

Oreochromis mossambicus

Reduced growth and appetite, loss of equilibrium, mortality (33)

C. carpio

Reduced growth (34,18); short body dwarfism, cataracts (18)

S. gairdneri

Cataracts (25,35); reduced growth, short body dwarfism (34,35); abnormal tail growth (34)

COPPER

C. carpio

Reduced growth (34,18); cataracts (18)

SELENIUM

S. salar

Increased mortality, muscular dystrophy, depressed glutathione peroxidase activity (36)

C. carpio

Reduced growth (18,37); cataracts (18); anaemia (37)

I. punctatus

Reduced growth (38)

IODINE

Salmonids

Thyroid hyperplasia (goitre; 39,40)

1/ 1-Ogino and Takeda (1976); 2-Yone and Toshima (1979); 3-Ogino et al. (1979); 4-Takeuchi and Nakazoe (1981); 5-Andrews, Murai and Campbell (1973); 6-Lovell and Li (1978); 7-Sakamoto and Yone (1980); 8-Sakamoto and Yone (1979); 9-Sakamoto and Yone (1978); 10-Arai, Nose and Kawatsu (1974); 11-Ogino and Chiou (1976); 12-Ogino and Takeda (1978); 13-Ketola (1975); 14-Lall and Bishop (1977); 15-Arai et al. (1975); 16-Arai, Nose and Hashimoto (1975); 17-Sakamoto and Yone (1973); 18-Satoh et al. (1983); 19-Gatlin et al. (1982); 20-Arai et al. (cited by Nose and Arai, 1979); 21-Cowey et al. (1977); 22-Knox, Cowey and Adron (1981); 23-Ogino, Takashima and Chiou (1978); 24-Knox, Cowey and Adron (1983); 25-Satoh et al. (1983a); 26-Sakamoto and Yone (1978a); 27-Sakamoto and Yone (1978b); 28-Kawatsu (1972); 29-Gatlin and Wilson (1983); 30-Ogino and Yang (1979); 31-Ogino and Yang (1978); 32-Wekell, Shearer and Houle (1983); 33-Ishak and Dollar (1968); 34-Ogino and Yang (1980); 35-Yamamoto et al. (1983); 36-Poston, Combs and Leibovitz (1976); 37-Lall (1979); 38-Gatlin and Wilson (1984); 39-Woodall and La Roche (1964); 40-NRC (1983).

Despite the presence of macro and trace elements in virtually all raw ingredients commonly used for fish feeding (Tacon and De Silva, 1983), and the ability of fish to absorb certain trace elements from the surrounding water, mineral deficiencies may arise under intensive culture conditions through:

- The absence of a specific macro or trace mineral premix within the diet (for details of specific mineral premix formulations see NRC, 1983).

- Reduced mineral bioavailability through dietary imbalances. The availability and utilization of dietary trace elements in fish is dependent upon the dietary source and form of the element ingested, the adequacy of stores within the body, interactions with other mineral elements present in the gastro-intestinal tract and within the body tissues (antagonisms), and finally by element interactions with other dietary ingredients or their metabolites (vitamins, fibre and phytic acid). For example. Table 2 shows the relative availabilities or apparent absorption efficiency of various forms or sources of dietary phosphorus for three fish species.

Table 2 - Availability or absorption of various sources of dietary phosphorus in fish 1/

Source

Channel catfish
(%)

Common carp
(%)

Rainbow trout
(%)

Phosphates

Sodium phosphate, mono

90

94

98

Potassium phosphate, mono

-

94

98

Calcium phosphate:


monobasic

94

94

94


dibasic

65

46

71


tribasic

-

13

64

Fish meals


Fish meal, white

-

0-18

66


Fish meal, brown

-

24

74


Fish meal, anchovy

40

-

-


Fish meal, menhaden

39

-

-

Protein sources


Egg albumin

71

-

-


Casein

90

97

90


Brewers yeast

-

93

91

Plant products


Rice bran

-

25

19


Wheat germ

-

57

58


Wheat middlings

28

-

-


Corn, ground

25

-

-


Soybean meal, with hulls

50

-

-


Soybean meal, dehulled

29-54

-

-


Phytate

0

8-38

0-19

1/ Source: NRC (1983)

For certain fish species the availability and absorption of phosphorus and other major elements (calcium) from fish meal and meat and bone meal is further complicated by the absence of an acid-secreting stomach, which is essential for normal bone solubilization. For stomachless fish species soluble monobasic inorganic salts or bioavailable organic salts must therefore be provided in the diet. Conversely, within plant proteins a large proportion of phosphorus is present as organically bound phytates. Not only is phytic acid phosphorus believed to be largely biologically unavailable, but phytic acid also hay the capacity to chelate other trace elements (iron, copper, zinc, cobalt, molybdenum) and by so doing may render them biologically unavailable to the fish during digestion (Spinelli, 1980).

Under practical farming conditions mineral deficiency signs often arise from a dietary imbalance of calcium; due to the antagonistic effect of excess dietary calcium on the absorption of phosphorus (Nakamura, 1982) and the trace elements zinc, iron and manganese (Lall, 1979). For example, the bioavailability of zinc, and to a lesser extent manganese, within white fish meal, has been found to be much lower than that contained in brown fish meal (which has a much lower ash and calcium content; Ketola, 1978, Watanabe, Takeuchi and Ogino, 1980). Thus in experimental feeding trials with rainbow trout, chum salmon and common carp fed on diets in which white fish meal was used without a trace element- supplement, overt trace element deficiency signs arise such as depressed growth, short body dwarfism and cataracts (Watanabe, Takeuchi and Ogino, 1980; Satoh et al. 1983, 1983a; Yamamoto et al. 1983).

4.2 Dietary mineral toxicity

A major hazard which may be associated with the use of unconventional dietary feed ingredients is the presence of heavy metal contaminants including the accumulative elements copper, lead, cadmium, mercury, arsenic, fluoride, selenium, molybdenum and vanadium. For example, contamination with copper may arise from products fermented within copper lined vessels (brewery by-products), or within pig and poultry excreta from the use of copper based growth stimulants or anti-fungal agents. Other feed ingredients which may contain metal contaminants include: poultry waste - arsenic; paper pulp waste - lead; fish meals -mercury, selenium, arsenic, cadmium and lead; poultry by-product meals - zinc; hydrolysed feather meals - zinc; shellfish - zinc, cadmium; seleniferous accumulating plants of the genera Astragalus and Machaeranthera, or cereals grown in seleniferous soils - selenium; Antartic krill - fluoride.

Dietary toxicity signs which have been reported in fish under laboratory conditions include:

Element

Fish

Toxicity sign 1/

Zinc

C. carpio

Reduced growth (dietary level above 300 mg/kg; 1)

Copper

I. punctatus

Reduced growth (dietary level above 15 mg/kg; 2)

Selenium

S. gairdneri.

Reduced growth and food conversion efficiency, high mortality (dietary levels above 13 mg/kg (3,4); nephrocalcinosis (4,5)

I. punctatus

Reduced growth (dietary levels above 15 mg/kg; 6)

Cadmium

S. gairdneri/C. carpio

Scoliosis, hyperactivity, decreased bone Ca content (7-10)

Lead

S. gairdneri

Scoliosis, lordosis, blacktail, anaemia, degeneration of caudal fin (11)

Chromium

S. gairdneri

Reduced growth and food conversion efficiency (12)

1/ 1-Jeng and Sun (1981); 2-Murai, Andrews and Smith (1981); 3-Hilton, Hodson and Slinger (1980); 4-Hicks, Hilton and Ferguson (1984); 5-Hilton and Hodson (1983); 6-Gatlin and Wilson (1984); 7-Koyama and Itazawa (1977); 8-Koyama and Itazawa (1977a); 9-Koyama and Itazawa (1979); 10-Roch and Maly (1979); 11-Johansson-Sjöbeck and Larsson (1979); 12-Tacon and Beveridge (1982)


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