Lipid nutrition and feeding of Cobia Rachycentron
canadum larvae
C.K. Faulk, G.J. Holt-2003
Journal of the World Aquaculture Society, 34(3):
368-378 (ISI Current Contents)
Abstract:
This study examined the fatty acid composition of cobia Rachycentron canadum
eggs and yolksac larvae, as well as the ovaries of wild caught females as an
initial guide to lipid nutritional requirements. A 2-wk feeding study also
was conducted to investigate the effectiveness of four dietary treatments on
the growth and survival of cobia larvae. Cobia eggs in the tailbud stage
contained 31.4 +/- 1.3 mug lipid/egg. After hatching, the amount of lipid
decreased significantly (P < 0.05) from 28.3 +/- 0.3 to 23.2 +/- 0.1 mug
lipid/larvae during the yolksac larval stage (days I to 3 after hatching).
Ovaries from wild caught adults and captive spawned eggs and yolksac larvae
contained high levels of PUFAs with docosahexaenoic acid (DHA),
eicosapentaenoic acid (EPA), and arachidonic acid (ARA) accounting for
approximately 80% of the total suggesting that cobia larvae may have a high
dietary requirement for these fatty acids. For the feeding study, larvae
were fed: 1) Artemia only; 2) enriched rotifers for I d only +
microparticulate diet (day 3-13); 3) enriched rotifers for 3 d (day 3-5) +
Artemia (day 3-13); and 4) enriched rotifers for 6 d (day 3-8) + Artemia
(day 3-13). Cobia larvae began feeding on rotifers 3 d after hatching and on
newly hatched Artemia nauplii by the fifth day following the onset of
exogenous feeding (day 7). On day 7, no differences in larval growth were
found among larvae fed rotifers for 3 versus 6 d, whereas larvae fed only
Artemia or rotifers for I d followed by microparticulate diet were
significantly smaller (P < 0.05) and did not survive beyond day 9 and 13,
respectively. The results of the feeding study indicate that cobia larvae
require rotifers for a minimum of 4 d following the onset of exogenous
feeding.
(Univ. Texas, Inst. Marine Sci. Fisheries & Mari
Lab., 750 Channel View Dr., Port Arkansas, TX 78373, USA)