Changes in gut content and
composition of juvenile Artemia after oil enrichment and during
starvation
G.G. Smith, A.J. Ritar, Ch.F. Phleger, M.M. Nelson,
B. Mooney, P.D. Nichols, P.R. Hart-2002
Aquaculture, 208(1-2): 137-158
Abstract:
Some larval crustacean tear Artemia to pieces
before ingestion. This results in the loss of gut contents, which may partly
negate the benefits of enrichment with essential fatty acids (EFA).
Therefore, the influence of gut content on the lipid composition of juvenile
Artemia (5 days old) was examined by starvation alone, or starvation
with forced gut evacuation using 20-30-µm plastic beads. Artemia gut
content, at 3 and 6 h after the completion of feeding, did not contribute
significantly to the total lipid or fatty acid profiles of the Artemia.
Artemia subjected to starvation alone (without beads) failed to
evacuate their gut over the 6-h starvation period, suggesting they require
the intake of suitable-sized particulate matter to undertake gut evacuation.
To assess the uptake of EFA in metanauplii (day 2) and juveniles, an
enrichment diet containing high levels of arachidonic acid [AA, 20:4n-6]
and eicosapentaenoic acid [EPA, 20:5n-3] was compared to a basal
oat-based diet and a commercial oil emulsion high in docosahexaenoic acid
[DHA, 22:6n-3]. Both AA and EPA were increased in juvenile Artemia
within a 24-h enrichment period at a rate proportional to their inclusion in
the enrichment, while DHA was incorporated to a lesser degree. For all three
EFA, the percentage loss during the 6-h starvation was small, but was
greater for DHA than EPA or AA. Juvenile Artemia, a life stage seldom
used in feeding regimes, have the ability to assume the AA and EPA profile
of their dietary source. The ability to produce a larger food source with a
non-traditional fatty acid profile may be valuable for a number of larval
crustacean and fish species.
(Marine Research Laboratories, Tasmanian Aquaculture
and Fisheries Institute, University of Tasmania, Nubeena Crescent, Taroona,
Tasmania 7053, Australia, Tel.: +61-3-6227-7265; fax: +61-3-6227-8035,
e-mail: greg.smith@dpiwe.tas.gov.au)