MILLIKIN: NUTRIENT REQUIREMENTS OF FISHES 



creased carcass fat and water content (Poston et 

 al. 1976). 



Vitamin E has been shown to be important in 

 reproductive physiology of fishes. Adult female 

 common carp (initial mean weight = 100 g) fed a 

 vitamin E-deficient diet for 17 mo displayed re- 

 duced weight gain, lower gonadosomatic index, 

 apparent muscular dystrophy (degenerative 

 epaxial muscles), higher muscle water content, 

 lower muscle protein content, and lower concen- 

 trations of yolk granules and yolk vesicles in 

 oocytes compared with individuals fed 700 mg 

 a-tocopherol/kg dry diet (Watanabe and Taka- 

 shima 1977). Also, developing ovaries of common 

 carp fed vitamin E-deficient diets had altered 

 polar lipid fractions in the form of lower concen- 

 trations of 20:4co6, 20:5a»3, and 22:6a»3 and higher 

 concentrations of 18:lco9 and 20:3a»9. 



Quantitative vitamin E requirements of fishes 

 depend upon interaction of several factors: 1) 

 Dietary concentration of polyunsaturated fatty 

 acids, 2) dietary selenium concentration, 3) die- 

 tary concentrations of proxidants and antioxi- 

 dants, 4) diet storage temperature, and 5) length 

 of diet storage. Woodall et al. (1964) reported 

 that a dietary vitamin E concentration of 5 to 30 

 mg a-tocopherol combined with 5% herring oil 

 provided satisfactory growth of chinook salmon 

 and prevented the occurrence of clinical defi- 

 ciency symptoms in this species. Common carp 

 fingerlings (initial mean weight = 1.6 g) required 

 about 100 mg a-tocopherol/kg dry diet in order to 

 maintain maximal growth rate and feed effi- 

 ciency (Watanabe et al. 1970b). Slightly larger 

 common carp fingerlings (initial mean weight = 

 6.4 g), fed 100 mg or less of DL-a-tocopheryl ace- 

 tate/kg dry diet concurrently with 5% dietary 

 methyl linoleate as the sole lipid component, dis- 

 played apparent muscular dystrophy and had 

 less weight gain than did fish fed 300 mg dl- 

 tocopheryl acetate/kg dry diet plus 5% methyl 

 linoleate (Watanabe et al. 1977). Also, common 

 carp fed 10 or 15% methyl linoleate plus 100 mg 

 DL-a-tocopheryl acetate, had significantly less 

 weight gain and higher occurrence of muscular 

 dystrophy than fish fed 2 or 5% methyl linoleate 

 plus 100 mg DL-a-tocopheryl acetate. Rainbow 

 trout fingerlings (initial mean weight = 0.9 g) 

 fed a diet containing 15% pollock liver oil (in the 

 form of methyl esters) displayed general vita- 

 min E deficiency signs (anorexia and reduced 

 growth), after 6 wk (Watanabe et al. 1981). Diets 

 supplemented with 50 mg a-tocopherol/kg dry 

 diet prevented anorexia and promoted growth 



rates equal to those fish fed 100, 300, or 500 mg 

 a-tocopherol/kg dry diet. However, the minimal 

 requirement may be slightly <50 mg a-tocopher- 

 ol/kg dry diet. Larger rainbow trout fingerlings 

 (initial mean weight = 10 g) require 20 to 30 mg 

 Di.-a-tocopheryl acetate/kg dry diet when fed 1% 

 18:3w3 plus 13% palmitic acid (Cowey et al. 

 1981a). Dietary vitamin E concentrations <20 

 mg DL-a-tocopheryl acetate/kg dry diet resulted 

 in higher molar ratios of polyunsaturated fatty 

 acid to tocopherol in rainbow trout livers. Also, 

 in vitro ascorbic acid-stimulated peroxidation in 

 mitochondria and microsomes was significantly 

 higher in rainbow trout fed low dietary vitamin 

 E concentrations (e.g., and 5 mg DL-a-tocopheryl 

 acetate/kg dry diet). Furthermore, these investi- 

 gators suggested that the vitamin E requirement 

 for rainbow trout is undoubtedly proportionally 

 higher with increasing dietary concentrations of 

 unsaturated fatty acids. Supplementary dietary 

 concentrations of either 33, 66, or 99 IU of DL-a- 

 tocopheryl acetate/kg dry diet added to 20 mg of 

 dietary a-tocopherol/kg dry diet, produced equal 

 growth rates, feed efficiency, and whole body 

 percentage protein, lipid, and moisture of rain- 

 bow trout fingerlings fed 12% dietary lipid 

 (Hung et al. 1980). In another study, diets con- 

 taining 24 mg of a-tocopherol/kg dry diet com- 

 bined with about 12% dietary lipid, which in- 

 cluded 7.5% dietary, unoxidized herring oil, 

 prevented vitamin E deficiency in rainbow trout 

 fingerlings (Hung et al. 1981). 



Vitamin K 



Dietary supplementation of vitamin K for sal- 

 monids has proven beneficial in increasing 

 hematocrit values of brook trout (Poston 1964) 

 and lake trout (Poston 1976b), whereas vitamin 

 K supplementation of diets fed to channel catfish 

 did not enhance blood clotting time or hemoglo- 

 bin concentrations (Murai and Andrews 1977). 

 Growth of each of the aforementioned species 

 was unaffected by dietary vitamin K supplemen- 

 tation. A dietary concentration of 1 mg menadi- 

 one dimethylpyrimidinol bisulfite/kg dry diet 

 was sufficient to provide normal coagulation and 

 packed cell volume of lake trout blood (Poston 

 1976b). Murai and Andrews (1977) concluded 

 that channel catfish have an extremely low, if 

 any, dietary vitamin K requirement, since indi- 

 viduals fed a diet devoid of vitamin K had similar 

 weight gain, blood clotting times, prothrombin 

 times, and hematocrit values to individuals fed 



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