Function and metabolism
diet were selected on the basis of their known nutritional quality and
their absence of two sterols, namely cholesterol and stigmasterol, which
were supplied by the emulsions.
For the present experiment, spats were fed algal diet supplemented
with 0%, 3%, 10%, and 20% wet weight emulsion per algal dry
weight. The emulsion contained a 1:1 mixture of the two previously
prepared emulsions. Algae were provided continuously using a reservoir
while emulsion was added twice a day.
After 7,19 and 33 days, the spats were harvested, rinsed, and weighed.
The WW, flesh weight (FW), DW, and organic matter (OM) of 10 replicates of five animals were measured. Other three replicates pooled spats
(five animal per replicate) were sampled for lipid analysis. The animals
sampled for lipid analysis were starved for 48 h to avoid artifacts of
sterols from microalgae and emulsion which could be present in the
digestive tract at the time of the sampling.
Lipid analysis
Total lipids were extracted according to Folch et al. (1957). Sterol were
analysed according to Soudant et al. (1998).
Statistics
Significant differences (p < 0.05) in biological and biochemical measurements between dietary treatments were determined by one-way
ANOVA. Multiple comparisons were determined by Neumans Keuls test.
Analyses were performed using Statistica computer package.
Results
Spat exhibited growth cluring the experiment but no significant difference was observed tn the WW, FW, DW, and OM quantities of spat
between all the dietary treatments along the experiment. The sterol supplementation clid not change the total sterol content of the spat.
The percentage of cholesterol decreased over time in all treatments
while brassicasterol and campesterol increased. However, the cholesterol decrease was gradually compensated by the increasing supply of
cholesterol provided by the emulsion (table 1). The percentage of stigmasterol in spats treated with emulsion increased strongly from 0 to
7 days and at a lesser extent from 19 to 33 days (table 1). In the control,
the level of stigmasterol was relatively unchanged.
The percentage of stigmasterol was statistically different between all
treatments after 7, 19 and 3.3 days of feeding (table 1). After 7 days,
only the cholesterol percentage of the groups fed 10% and 20%. of
emulsion (WW/DW of microalgae) was significantly different from the
control. After 19 days of emulsion supplementation, the percentages of
cholesterol differed significantly among all groups. After 33 days, the
cholesterol percentages of groups fed 10 and 20% emulsion were
significantly higher than the control and the group fed 3% emulsion.
125
diet were selected on the basis of their known nutritional quality and
their absence of two sterols, namely cholesterol and stigmasterol, which
were supplied by the emulsions.
For the present experiment, spats were fed algal diet supplemented
with 0%, 3%, 10%, and 20% wet weight emulsion per algal dry
weight. The emulsion contained a 1:1 mixture of the two previously
prepared emulsions. Algae were provided continuously using a reservoir
while emulsion was added twice a day.
After 7,19 and 33 days, the spats were harvested, rinsed, and weighed.
The WW, flesh weight (FW), DW, and organic matter (OM) of 10 replicates of five animals were measured. Other three replicates pooled spats
(five animal per replicate) were sampled for lipid analysis. The animals
sampled for lipid analysis were starved for 48 h to avoid artifacts of
sterols from microalgae and emulsion which could be present in the
digestive tract at the time of the sampling.
Lipid analysis
Total lipids were extracted according to Folch et al. (1957). Sterol were
analysed according to Soudant et al. (1998).
Statistics
Significant differences (p < 0.05) in biological and biochemical measurements between dietary treatments were determined by one-way
ANOVA. Multiple comparisons were determined by Neumans Keuls test.
Analyses were performed using Statistica computer package.
Results
Spat exhibited growth cluring the experiment but no significant difference was observed tn the WW, FW, DW, and OM quantities of spat
between all the dietary treatments along the experiment. The sterol supplementation clid not change the total sterol content of the spat.
The percentage of cholesterol decreased over time in all treatments
while brassicasterol and campesterol increased. However, the cholesterol decrease was gradually compensated by the increasing supply of
cholesterol provided by the emulsion (table 1). The percentage of stigmasterol in spats treated with emulsion increased strongly from 0 to
7 days and at a lesser extent from 19 to 33 days (table 1). In the control,
the level of stigmasterol was relatively unchanged.
The percentage of stigmasterol was statistically different between all
treatments after 7, 19 and 3.3 days of feeding (table 1). After 7 days,
only the cholesterol percentage of the groups fed 10% and 20%. of
emulsion (WW/DW of microalgae) was significantly different from the
control. After 19 days of emulsion supplementation, the percentages of
cholesterol differed significantly among all groups. After 33 days, the
cholesterol percentages of groups fed 10 and 20% emulsion were
significantly higher than the control and the group fed 3% emulsion.
125