Effect of
conjugated linoleic and docosahexaenoic acids on growth of juvenile tilapia Oreochromis
niloticus
A. Yasmin, T. Takeuchi, M. Hayashi, T. Hirota, W. Ishizuka, S.
Ishida-2004
Fisheries
Science, 70(3):
473-481
Abstract:
The present study was conducted to
investigate the effects of dietary conjugated linoleic acid (CLA)- and
conjugated docosahexaenoic acid (CDHA)-supplemented diets on the growth and
body lipid composition of tilapia Oreochromis niloticus. Four dietary
treatments of linoleic acid (LA), CLA, docosahexaenoic acid (DHA) and CDHA
were tested in this experiment over a feeding period of 9 weeks. The initial
average body weight and length of fish were 4.53 ± 0.96 g
and 5.18 ± 0.34 cm, respectively, and temperature was
maintained at 25 ± 1°C. Two replicate groups and two control
groups of fish were applied among the four dietary treatments and each group
consisted of 20 juvenile fish. Growth rate, feed efficiency and tissue lipid
contents were not significantly affected (P < 0.05) by
CLA compared to the LA control group. A higher level of hepatosomatic index
and lower growth rate were obtained from the CDHA dietary group. CLA and
CDHA isomers were detected mainly in non-polar lipids of muscle, liver and
brain. Lower values of mono-unsaturated fatty acids and 18:2n-6 levels were
found in the CLA dietary fish group and there was no effect on the 20:4n-6
level in muscle, liver and brain. Conversely, higher levels of total
mono-unsaturated fatty acids were found in liver and the 20:5n-3, 22:5n-3
level of the muscle polar fraction in the CDHA dietary fish group. These
results indicate that 5% of CLA in diet does not influence the growth and
feed efficiency of juvenile tilapia and that CLA was observed to be
incorporated into muscle, liver and brain. Lower growth and higher liver
lipid contents were observed in the CDHA-supplemented dietary fish group.
(Tokyo University of Marine Science and Technology,
Minato, Tokyo 108-8477, Japan, e-mail of T. Takeuchi: take@s.kaiyodai.ac.jp)