Function and metabolism
FAMEs were identified comparing of their retention times with those
from standard mixtures (Sigma Chemical CO, Saint Louis, MO). The identification of each compound was confirmed by gas chromatography -
mass spectrometry (CG-MS) performed on selected samples. CG/MS analysis were performed with an HP 5890 series II chromatograph fitted
with HP 5790 mass selective detector (MSD). The capillary column,
injector and chromatography conditions were the same as those
described above. The conditions for the MSD were as follows: electron
impact mode (70 eV), source temperature 180°C, mass range m/z 33300 amu, electron multiplier voltage 1700 V, and scan rate 1.9 sec' 1 .
FAMEs of oyster samples were identified by comparing their spectra
with those of a commercial spectra database (NBS 75k and internal
library of the laboratory). The position of the ultimo double bound
were assigned according to the data previously published on Skeletonema
costatum by Bergé et al. (1995).
Statistical analysis: the results of condition index were expressed as
mean of 30 determinations ± confidence interval at 95% while the results
of glycogen and lipid contents and fatty acid composition were expressed
as mean of 3 determinations ± confidence interval at 95 per cent.
Results
Proximal composition
Changes in index condition, glycogen and total lipid contents in
control and supplemented oysters are shown in table 1. Condition index
increased from 26 to 56 in supplemented oysters while it remained
constant in the control group during the period of the experiment.
Similarly, the glycogen content remained steady in the control group
(5 g/100 g of dry flesh) whereas in supplemented oysters, it remained
stable during the first week and then increased from 5.0 to 24.4 g/100 g
dry flesh at six weeks. The total lipid content generally decreased during
the experiment from 8.4 to 7.2 g/100 g of flesh dry matter in the
control oysters while it increased in supplemented oysters from 8.4 to
10.4 g/100 g of flesh dry matter. However, the difference between the
groups only became significantly different after six weeks of feeding.
Table 1 - Change in condition index, glycogen and total lipid contents (g/100 g of dry matter) of control
and supplemented oysters during fattening (means ± confidence interval at 95%).
Weeks
0
1
2
3
4
6
Condition index
Controls 26,0 (1.8) 24,3 (1.9) 23,0 (2.2) 23,6 (2.1) 24,2 (1.7) 20,9 (1.8)
Supplem. 2O.0 (1.8) 32,3 (2.6) 37,6 (2.0 45,8 (3.9) 54.6 (3.0*) 50,2 (4.1)
Glycogen content Controls
5,0 (1,1)
0,7 (0,6)
5,4 (0,1)
4,5 (0.6)
4,4
(0,6)
4,0 (1.3)
Supplem.
5,0 (1,1)
0,5 (1,2) 13,4 (0.1) 18,4 (1.1) 18,6 (0.2) 24,4 (3.0)
Total lipid content Controls
8,4 (0.4)
6,7 (1.0) 7,5 (2.0 7,7 (0.0, 6,6 (0.6) 7,2 (1.4)
Supplem.
8,4 (0.4)
8,8 (0,3)
0,1 (0.8)
0,0 (0.4)
9,3 (0.8) 10,4 (1.1)
115
FAMEs were identified comparing of their retention times with those
from standard mixtures (Sigma Chemical CO, Saint Louis, MO). The identification of each compound was confirmed by gas chromatography -
mass spectrometry (CG-MS) performed on selected samples. CG/MS analysis were performed with an HP 5890 series II chromatograph fitted
with HP 5790 mass selective detector (MSD). The capillary column,
injector and chromatography conditions were the same as those
described above. The conditions for the MSD were as follows: electron
impact mode (70 eV), source temperature 180°C, mass range m/z 33300 amu, electron multiplier voltage 1700 V, and scan rate 1.9 sec' 1 .
FAMEs of oyster samples were identified by comparing their spectra
with those of a commercial spectra database (NBS 75k and internal
library of the laboratory). The position of the ultimo double bound
were assigned according to the data previously published on Skeletonema
costatum by Bergé et al. (1995).
Statistical analysis: the results of condition index were expressed as
mean of 30 determinations ± confidence interval at 95% while the results
of glycogen and lipid contents and fatty acid composition were expressed
as mean of 3 determinations ± confidence interval at 95 per cent.
Results
Proximal composition
Changes in index condition, glycogen and total lipid contents in
control and supplemented oysters are shown in table 1. Condition index
increased from 26 to 56 in supplemented oysters while it remained
constant in the control group during the period of the experiment.
Similarly, the glycogen content remained steady in the control group
(5 g/100 g of dry flesh) whereas in supplemented oysters, it remained
stable during the first week and then increased from 5.0 to 24.4 g/100 g
dry flesh at six weeks. The total lipid content generally decreased during
the experiment from 8.4 to 7.2 g/100 g of flesh dry matter in the
control oysters while it increased in supplemented oysters from 8.4 to
10.4 g/100 g of flesh dry matter. However, the difference between the
groups only became significantly different after six weeks of feeding.
Table 1 - Change in condition index, glycogen and total lipid contents (g/100 g of dry matter) of control
and supplemented oysters during fattening (means ± confidence interval at 95%).
Weeks
0
1
2
3
4
6
Condition index
Controls 26,0 (1.8) 24,3 (1.9) 23,0 (2.2) 23,6 (2.1) 24,2 (1.7) 20,9 (1.8)
Supplem. 2O.0 (1.8) 32,3 (2.6) 37,6 (2.0 45,8 (3.9) 54.6 (3.0*) 50,2 (4.1)
Glycogen content Controls
5,0 (1,1)
0,7 (0,6)
5,4 (0,1)
4,5 (0.6)
4,4
(0,6)
4,0 (1.3)
Supplem.
5,0 (1,1)
0,5 (1,2) 13,4 (0.1) 18,4 (1.1) 18,6 (0.2) 24,4 (3.0)
Total lipid content Controls
8,4 (0.4)
6,7 (1.0) 7,5 (2.0 7,7 (0.0, 6,6 (0.6) 7,2 (1.4)
Supplem.
8,4 (0.4)
8,8 (0,3)
0,1 (0.8)
0,0 (0.4)
9,3 (0.8) 10,4 (1.1)
115