EFFECTS OF DIFFERENT KINDS OF DIETARY-LIPID ON GROWTH AND FATTY-ACID COMPOSITION OF JUVENILE SUNSHINE BASS, MORONE-CHRYSOPS FEMALE X MORONE-SAXATILIS MALE
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An 8-week feeding trial was conducted to provide preliminary information on essential fatty acid requirements of sunshine bass by determining the effects of different kinds of lipid on growth, health and tissue fatty acid composition. Five semipurified diets containing 40% crude protein from fish muscle and crystalline amino acids with 3.45 kcal available energy/g were supplemented with 5% of either coconut, olive, safflower, linseed or menhaden fish oils. Each diet was fed in triplicate to groups of fish initially weighing 4.00.14 g (means.d.) in 110-liter aquaria connected as a closed recirculating system containing fresh well water with hardness of 18010 mg/l as CaCO3 at 241C. At the end of 5 weeks, fish fed the diets containing coconut, olive, safflower and linseed oils had significantly (P<0.01) reduced weight gain compared to fish fed the diet containing menhaden fish oil (MFO). After 5 weeks, fish fed all diets except the one supplemented with MFO began to exhibit erosion of the caudal fin and skin irritation. Mortality of fish fed these diets approached 80% by the end of 8 weeks, while no mortality was observed for fish fed MFO. At the end of 8 weeks, significantly greater weight gain as well as better feed efficiency and protein efficiency values were observed for fish fed the diet supplemented with MFO. Lowest weight gain, feed efficiency and protein efficiency values were observed for fish fed the diet supplemented with coconut oil and intermediate responses were observed for fish fed the other oils. Fatty acid composition of body lipids (total lipid of intraperitoneal fat as well as neutral and polar lipids of liver and muscle) was affected by dietary oils except for fish fed the diet containing coconut oil. Moreover, elongation and desaturation of fatty acids (18:1n-9, 18:2n-6 and 18:3n-3) was not observed. These data indicate that n-3 highly unsaturated fatty acids such as eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids in MFO are essential for maximum growth, feed efficiency and survival of sunshine bass. 1993.
