| dc.description.abstract | Long chain omega-3 PUF As; EPA and DHA found mainly in fish, have been reported to
have cardio-protective and other health benefits in humans. Unfortunately, capture
fisheries cannot meet the demand for these fatty acids. As a result aquaculture has been
on the increase with tilapia being one of the most cultured fishes. Recent studies
however, have reported the presence of harmful combination of fatty acid (high n-6: n-3)
in cultured tilapia as a result of inclusion of plant oil high in omega-6 in their diet. To
achieve a low n-6: n-3 ratio, the aquaculture industry has shifted its attention to
identifying alternative sources of n-3 for inclusion in fish feeds.
The present study was conducted to evaluate Salvinia molesta an invasive aquatic weed
as an alternative source of omega-3 for cultured tilapia. In triplicate groups of] 00, tilapia
fingerlings weighing 0.35 ± 0.03g (mean ±SE) were fed on either commercial tilapia
fingerling feed only, or commercial feed supplemented with S. molesta at 10, 20 or 30 %,
for a period of 56 days. Lipids were extracted from feed and the fish fillet using the Folch
method and fatty acid profile analyzed by gas chromatography.
Results from this study showed that inclusion of S. molesta in the experimental diets had
no significant impact on fish growth (p:S0.05). However, the concentration of n-3 in fish
oil extracted from fish fillet increased as the level of S. molesta in diet increased (0.71 to
1.45mglg of feed, control & 30% S. molesta diet respectively). This also caused an
overall decrease in the n-6: n-3 ratio in fillet from 6: 1 in fish fed commercial diet only to
4:1 in fish receiving 30% S. molesta.
Although supplementation of commercial feed with S. molesta increased the amount of n-
3 in the experimental fish diet and the fillet, the effect was however minimized by the
large amount of linoleic acid (n-6) in the commercial diet. Results from this study
provide evidence that S. molesta is a good and potential source of n-3 for cultured tilapia
that can be utilized at industrial scale. | en |
