Algal by-product meals from
the Hawaiian biofuels industry were evaluated as ingredients in diets for juveniles
of Nile tilapia (Oreochromis niloticus). Four experimental diets were
formulated to fulfill fish nutritional requirements. The diets were made with
fish meal, soybean meal, whole diatom (Nanofrustulum
sp.) meal, or defatted green algae (Desmochloris
sp.) meal as the test ingredients. A
feeding experiment with juvenile tilapia of 2.6 ±0.1 g initial weight was
carried out in a freshwater recirculation system with each diet treatment
tested in triplicate tanks. Fish were fed the experimental diets to apparent
satiation twice a day for 12 weeks and fish weight was measured every three
weeks. Water temperature was maintained at 22.7 ±0.8 °C, salinity at 0.1
±0.0 ppt and dissolved oxygen at 5.6 ±0.5 mg/L. At the end of the experiment a significant effect (P<0.05) of diet
treatments was found in fish growth and feed utilization, with specific growth
rate, food conversion ratio, and retained nitrogen efficiency being highest
for the green algae-based diet. Lipid content in the diets was lower than expected
for the algae diets. Proximate composition analysis showed no significant difference (P>0.05)
in the protein content of the
fish bodies among the diets. Results indicate the suitability of the green
algae by-product meal as an ingredient in Nile tilapia diets. Diatom meal also
showed interesting potential for use as an ingredient in tilapia feeds.
Nile tilapia microalgae diatom green algae fish feeds Hawaii
Subjects | Hydrobiology |
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Journal Section | Articles |
Authors | |
Publication Date | May 18, 2015 |
Published in Issue | Year 2015 Volume: 1 Issue: 4 |