Table 2.
Growth performance and body indices of juvenile rainbow trout fed FM-based diets containing microalgae to replace fish oil and synthetic astaxanthin
| Diets1 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Fish oil replacement2 | 0% | 50% | 100% | Fish oil | ASTA | P-values11 | ||||
| Astaxanthin source | SA | AA | SA | AA | SA | AA | RMSE | Level | Source | Interaction |
| Growth performance | ||||||||||
| Average fish Wt (g) | 386a | 367a | 353a | 380a | 169b* | 147b | 15 | <0.0001 | 0.47 | 0.025 (100SA > 100AA) |
| Percent increase3 (%) | 1680a | 1610a | 1530a | 1660a | 678b* | 591b | 67 | <0.0001 | 0.90 | 0.027 (100SA > 100AA) |
| BW/day4 (%) | 0.80b | 0.77b | 0.83b | 0.78b | 1.24a | 1.43a* | 0.07 | <0.0001 | 0.36 | 0.030 (100SA < 100AA) |
| FCR5 | 0.92b | 0.88b | 0.96b | 0.89b | 1.52a | 1.77a* | 0.09 | <0.0001 | 0.32 | 0.024 (100SA < 100AA) |
| Body indices | ||||||||||
| Survival (%) | 93 | 100 | 98 | 100 | 97 | 98 | 3.7 | 0.52 | 0.08 | 0.43 |
| VSI6 (%) | 10.7b | 9.6b | 11.7a | 13.1a | 12.2a | 12.2a | 1.03 | 0.004 | 0.80 | 0.14 |
| FR7 (%) | 59.3 | 59.6 | 59.5 | 60.8 | 57.0 | 56.4 | 2.38 | 0.06 | 0.77 | 0.82 |
| HSI8 (%) | 1.1b | 1.1b | 1.3a | 1.3a | 1.2b | 1.2b | 0.12 | 0.04 | 0.70 | 0.96 |
| PRE9 (g) | 40.6a | 45.6a | 40.9a | 45.6a | 22.3b* | 17.9b | 3.12 | <0.0001 | 0.26 | 0.04 (100SA > 100AA) |
| ERE10 (kcal/g) | 55.0a | 53.6a | 53.6a | 61.1a | 29.9b | 27.1b | 4.24 | <0.0001 | 0.59 | 0.11 |
1SA, synthetic astaxanthin; AA, microalgal astaxanthin; ASTA, astaxanthin.
2Percent of fish oil replaced by mciroalgae on a crude lipid basis of DHA.
3Percent increase (%) = (final weight – initial weight) × 100/initial weight.
4BW/day (%) = (tank feed consumption total/average tank weight)/study duration × 100.
5FCR, feed conversion ratio = g feed consumed/g weight gained.
6VSI= gut weight/body weight × 100.
7FR= fillet wt × 2/body weight × 100.
8HSI= liver weight/body weight × 100.
9PRE, protein retention efficiency = g protein gain × 100/g protein fed.
10ERE, energy retention efficiency = kcal energy gain × 100/ kcal energy fed.
11Probability associated with the F-statistic. A significant (P < 0.05) main effect without significant interaction allowed data to be pooled. Significant main effects are denoted under level and source.
a,b,cMeans without sharing a common letter are different (P < 0.05). Direct comparisons of means across the 2 treatments should be made conditionally if there was an interaction.
*SA vs. AA, P < 0.05.