Ž .
apparent satiation twice per day 0900 and 1700 during a 30-min period, and the Ž
. amount of diet consumed was recorded daily. Every 2 weeks, the standard length SL
Ž .
and wet weight W of the total population were recorded. At the end of the experiment, Ž
. 90 fish were killed 10 per replicate to assay for crude protein, ether extract, and ash
content of liver and muscle. For each replicate, two or three whole fish were used to Ž
. determine proximate composition according to AOAC 1995 methods, and gross energy
Ž .
in an adiabatic bomb calorimeter Parr model 1261 Moline, IL, USA . All samples were stored at y508C, then lyophilized before the analytical procedures. The biochemical
analysis of diets, fish, and tissue samples were conducted in triplicate. Growth rate was determined after a logarithmic transformation of the wet weight, by
b X
Ž .
a covariance analysis using the model Y s ae Everhart et al., 1953 . The comparison
Ž . Ž
. between slopes b was made using a Tukey test Zar, 1996 . Survival was evaluated at
the end of the experiment, using the test of hypothesis of the difference among the Ž
. proportions of two populations Daniel, 1997 . Normality of distribution and homogene-
ity of variance were tested. Data were analyzed by a one-way ANOVA with level of protein as factor. When the data were not normally distributed, a Kruskal–Wallis
Ž analysis was used SL, proximate composition of whole fish, muscle, and liver, growth
. variables . Means were compared by a Duncan’s multiple range test or Tukey nonpara-
Ž .
metric multiple test. Statistical analyses were made using STATISTICA v. 5.1
Ž .
StatSoft, Tulsa, OK, USA . All analysis were made at 0.05 significance level.
3. Results
Significant differences between protein levels were detected for wet weight on days Ž
. 35, 49, and 93. The lowest weight was for the 40 protein diet Table 2 . Significant
difference was detected for SL only on day 35 when fish fed the 45 protein diet were smaller than fish fed the other protein levels.
However, at the end of the experiment, no significant difference could be detected Ž
. between fish fed the different dietary protein levels for SL Table 2 . Fish fed the 45
Table 2 Ž .
Ž .
Weight g and standard length cm of spotted sand bass juveniles fed different dietary protein levels Ž
. MeanSD
Ž .
Ž . Ž
. Sampling days
Weight g SL cm
Ž . Ž .
Protein level Protein level
40 45
50 40
45 50
9.20.1 9.10.1
9.30.1 7.50.2
7.50.2 7.50.2
18 13.90.2
13.70.2 14.10.2
8.50.3 8.40.3
8.50.3
a ab
b a
b a
35 20.40.3
20.40.3 21.60.4
9.30.5 9.10.5
9.30.5
a ab
b
49 26.70.4
27.50.5 28.40.5
10.10.6 10.10.6
10.20.6 63
33.00.6 33.90.6
34.90.7 10.90.7
10.90.7 10.90.7
78 38.20.8
39.80.8 40.80.9
11.20.7 11.30.8
11.20.7
b a
a
93 43.10.9
45.81.0 46.51.0
11.70.8 11.80.8
11.80.8 Ž
. Means in the same row with different superscript are significantly different P - 0.05 .
Table 3 Growth variables and percent survival of spotted sand bass juveniles fed different dietary protein levels for 93
Ž .
days MeanSD Ž .
Protein level 40
45 50
1 b
a a
Ž .
SGR rday 1.650.05
1.740.06 1.730.32
2
Ž .
ADG grday 0.360.02
0.390.03 0.400.01
3
CF 2.720.03
2.800.04 2.830.04
4
Ž . WG
33025 35425
35823
5
Ž . Survival
93.71.4 93.75.5
97.62.4 Ž
. Means in the same row with different superscript are significantly different P - 0.05 .
1
Ž . wŽ
. x
Specific growth rate SGR : ln final weightyln initial weight rdays =100.
2
Ž . Ž
. Average daily gain ADG : final mean weightyinitial mean weight rnumber of days.
3
Ž . Ž
3
. Condition factor CF : final mean body weightrfinal mean body length =100.
4
Ž . wŽ
. Ž .x
Weight gain WG : final mean weightyinitial mean weight r final mean weight =100.
5
Ž . Ž .
Survival : final fish numberrinitial fish number =100.
and 50 protein diets showed higher specific growth rates, whereas no significant Ž
. difference was detected for average daily gain ADG , condition factor, and percent
Ž .
Ž weight gain Table 3 . Survival of fish at the end of the experiment was high above
. 93 and unaffected by diets.
Ž .
Daily feed intake was similar among treatments 0.57, 0.59 and 0.56 grfish ,
Ž .
Ž .
whereas gross energy retention GER and daily protein gain DPG were significantly higher in fish fed the 45 and 50 protein diets than in those fed the 40 protein diet
Ž .
Table 4 . No significant difference was detected for the other feed utilization variables. Ž
. For biochemical composition Table 5 , the fat content of liver varied from 64.2 to
Table 4 Ž
. Feed efficiency of spotted sand bass juveniles fed different dietary protein levels for 93 days MeanSD
Ž . Protein level
40 45
50
1
DFI 0.570.04
0.590.03 0.560.03
2
FCR 1.600.04
1.530.05 1.430.11
3
PER 1.480.04
1.420.05 1.340.11
4
Ž . PPV
43.471.07 44.221.25
43.493.15
5 b
a a
Ž . GER
19.70.5 22.40.7
24.81.9
6
Ž .
DEG kJrfish 10.70.4
11.00.3 10.60.2
7 b
a a
Ž .
DPG mgrfish 221.212.1
256.310.1 273.914.7
Ž .
Means in the same row with different superscript are significantly different P - 0.05 .
1
Ž . Ž
. Daily feed intake DFI : feed intake, g dry matter rnumber of fishrday.
2
Ž . Ž
. Ž .
Feed conversion ratio FCR : feed intake, g dry matter r fish weight gain, g .
3
Ž . Ž
. Ž .
Protein efficiency ratio PER : fish wet weight gain, g r protein intake, g .
4
Ž . Ž
. Ž
Protein productive value PPV : final body protein=final body weight y initial body protein= . Ž
Ž . Ž .
. initial body weight r total protein intake g =weight gain g =100 .
5
Ž . Ž
. Ž .
Gross energy retention GER : fish energy gain, kJ r energy intake, kJ =100.
6
Ž . Ž
. Ž
. Ž
. Daily energy gain DEG : energy intake, g rtime days = N final number of fish .
7
Ž . Ž
. Ž
. Ž
. Daily protein gain DPG : protein intake, g rtime days = N final number of fish .
Table 5 Ž
. Biochemical composition dry matter of spotted sand bass juveniles fed different dietary protein levels
Ž .
MeanSD Ž .
Protein level 40
45 50
Whole fish Ž .
Crude protein 57.860.52
57.241.33 56.620.62
Ž . Ether extract
28.161.07 28.800.24
29.420.68 Ž .
Ash 13.430.14
13.210.30 12.520.30
Ž .
Gross energy calrg 566669
568667 572777
Ž . Moisture
74.100.04 72.350.08
71.380.06 LiÕer
Ž . Crude protein
15.240.03 14.240.44
13.730.55 Ž .
Ether extract 64.240.47
66.371.28 69.710.27
Ž . Ash
1.670.15 1.480.02
1.470.07 Muscle
Ž . Crude protein
70.911.15 72.160.32
72.710.58 Ž .
Ether extract 22.642.26
22.470.82 20.970.58
Ž . Ash
5.600.23 5.680.23
5.870.22
69.7 for diets containing 40 and 50 dietary protein, Nevertheless, no differences in whole fish, liver, or muscle composition were found among dietary treatments.
4. Discussion
