Table 3. Growth parameters, feed intake, exposure estimation, survival, proximate body composition and organ weights of Atlantic salmon (Salmo salar L.) exposed to graded levels of EQ through their diet for 90 days.
| Dietary treatment | |||||||
|---|---|---|---|---|---|---|---|
| Growth parameters | EQ 0 | EQ 1 | EQ 2 | EQ 3 | EQ 4 | EQ 5 | P-values |
| Final length (cm) | 36.3 ± 3.5 | 37.0 ± 3.6 | 37.6 ± 3.3 | 37.9 ± 3.0 | 34.4 ± 3.1 | 29.4 ± 3.2* | < .0001 |
| Final body weight (g) | 716.3 ± 234.5 | 728.1 ± 222.9 | 784.5 ± 197.2 | 756.7 ± 190.7 | 537.2 ± 155.5* | 301.5 ± 111.5* | < .0001 |
| Body weight gain (g) | 454.2 ± 234.5 | 467.5 ± 222.4 | 515.3 ± 197.4 | 493.9 ± 190.6 | 275.8 ± 155.4* | 37.61 ± 111.7* | < .0001 |
| Specific growth rate (%*day-1) | 1.1 ± 0.3 | 1.1 ± 0.3 | 1.2 ± 0.3 | 1.1 ± 0.3 | 0.8 ± 0.3* | 0.1 ± 0.4* | < .0001 |
| Condition factor (g/cm3) | 1.5 ± 0.1 | 1.4 ± 0.1 | 1.4 ± 0.1 | 1.4 ± 0.1 | 1.3 ± 0.1* | 1.1 ± 0.1* | < .0001 |
| Mean daily feed intake (g*fish-1)a | 4.9 ± 0.1 | 4.6 ± 0.6 | 5.1 ± 0.3 | 4.4 ± 0.4 | 2.9 ± 0.1* | 1.1 ± 0.3* | < .0001 |
| Mean total feed intake (g*fish-1)b | 435.9 ± 4.0 | 407.4 ± 50.7 | 452.6 ± 25.5 | 397.6 ± 32.5 | 255.0 ± 6.2* | 100.0 ± 24.4* | < .001 |
| Feed conversion rate (*fish-1) | 1.0 ± 0.2 | 0.9 ± 0.1 | 0.9 ± 0.1 | 0.8 ± 0.1 | 0.9 ± 0.1 | 4.0 ± 3.3 | 0.072 |
| Total EQ consumed (mg*fish-1) | 0.205 ± 0.002 | 17 ± 2 | 54 ± 3 | 466 ± 38* | 1016 ± 25* | 966 ± 236* | < .001 |
| Estimated daily EQ exposure (mg*kg BW-1*day-1)c |
0.0049 ± 0.0002 | 0.41 ± 0.05 | 1.22 ± 0.04 | 11 ± 1* | 30 ± 2* | 40 ± 10* | < .001 |
| Survival (%) | 100 | 100 | 100 | 100 | 100 | 100 | |
| Proximate body composition whole fish (% ww) | |||||||
| Crude protein (N*6.25) | 17.3 ± 0.6 | 18.0 ± 0.0 | 17.7 ± 0.6 | 18.0 ± 1.0 | 17.7 ± 0.6 | 17.3 ± 0.6 | 0.643 |
| Crude lipid | 15.2 ± 0.4 | 14.1 ± 0.2 | 14.1 ± 0.5 | 13.3 ± 0.4* | 11.0 ± 0.4* | 8.7 ± 1.3* | < .001 |
| Ash | 1.8 ± 0.2 | 1.8 ± 0.2 | 2.0 ± 0.2 | 1.8 ± 0.1 | 1.9 ± 0.1 | 2.1 ± 0.1 | 0.207 |
| Dry matter | 34.0 ± 1.4 | 33.3 ± 0.7 | 33.9 ± 1.6 | 33.3 ± 0.6 | 30.0 ± 0.1* | 27.8 ± 1.1* | < .001 |
| Crude lipid muscle | 4.1 ± 1.0 | 3.5 ± 0.1 | 3.7 ± 0.7 | 4.0 ± 0.4 | 2.7 ± 0.1* | 1.8 ± 0.7* | < .01 |
| Organ weights | |||||||
| Heart (g) | 0.8 ± 0.3 | 0.8 ± 0.2 | 0.9 ± 0.2 | 0.8 ± 0.2 | 0.6 ± 0.2 | 0.4 ± 0.1* | < .001 |
| Cardiosomatic index (*100) | 0.12 ± 0.01 | 0.10 ± 0.01 | 0.11 ± 0.01 | 0.10 ± 0.01 | 0.11 ± 0.01 | 0.12 ± 0.02 | 0.108 |
| Liver (g) | 8.0 ± 2.9 | 7.8 ± 2.4 | 8.8 ± 2.2 | 8.2 ± 2.5 | 6.7 ± 2.0 | 3.2 ± 1.3* | < .001 |
| Hepatosomatic index (*100) | 1.05 ± 0.10 | 1.02 ± 0.08 | 1.08 ± 0.08 | 1.08 ± 0.12 | 1.16 ± 0.10 | 1.01 ± 0.20 | 0.102 |
| Spleen (g) | 0.6 ± 0.2 | 0.6 ± 0.3 | 0.6 ± 0.2 | 0.6 ± 0.3 | 0.5 ± 0.1 | 0.2 ± 0.1* | < .01 |
| Spleen somatic index (*100) | 0.08 ± 0.02 | 0.08 ± 0.02 | 0.08 ± 0.01 | 0.08 ± 0.02 | 0.09 ± 0.03 | 0.07 ± 0.02 | 0.067 |
Measurements performed on tank pooled samples or tank means (n = 3/group) were analyzed performing one-way ANOVA and Tukey’s test for multiple comparison of group means. For parameters including replicate measurements from the individual tanks, a nested ANOVA was fit using a mixed effects model (n = 25–30) with tank treated as a random effect, and post-hoc comparison of least-square group means adjusting for multiple comparisons. Results are presented as means ± SD of all measurements.
* p<0.05, compared to the control (EQ 0).
a Daily feed intake recorded per tank divided by number of fish.
b Sum of daily feed intake per fish
c Calculated from daily feed intake per fish and interpolated body weight per fish. Abbreviation: BW, Body weight.