Based on initial responses of S. auratus fry from the Bardawil Lagoon and feed ingredient inventory, the following experimental design was established. Tests will be run in 12 200 litre fibreglass tanks, i.e., four diets with three replicates of each. Food will be of granular type (420 – 1 000 μ) delivered in automatic feeders with unlimited continuous feeding. Stocking density is at ~ 50 fish/tank of approximately 0.5 – 0.6 g size. Experiments are planned for a four-week period, depending on rate and overall increase in weight, or until animals attain stocking size. Experiments are planned for a four-week period, depending on rate and overall increase in weight, or until animals attain stocking size of from > 2 to less than 5 g per speciman.
Table 7
Composition of Experimental Fry Diets
| Diet Ingredients | Percent Composition | |||
| B-1M-2 (48) | B-1M-3 (48) | B-1M-4 (53) | B-1M-5 (53) | |
| Fish meal | 50% | 50% | 50% | 53% |
| Meat meal | 10 | 10 | -- | -- |
| Fish protein concentrate* | 5 | 5 | 15 | 15 |
| Liver protein concentrate* | -- | -- | 2 | 2 |
| Wheat starch | -- | -- | -- | 2 |
| Pregelatinized starch* | 12 | 10 | 10 | 10 |
| Fish oil* | 6 | 8 | 6 | 6 |
| Soybean oil | 2 | 2 | 2 | 2 |
| Fish hydrolysate* | 5 | 5 | 5 | . 5 |
| Fish solubles* | 5 | 5 | 5 | 5 |
| Vitamin premix | 1 | 1 | 1 | 1 |
| Ascorbic acid (coated)* 300 mg/Kg | -- | -- | -- | -- |
| Mineral premix | 4 | 4 | 4 | 4 |
| Calculated protein level | 48% | 48% | 53% | 53% |
| Calculated fat level | 8% | 10% | 8% | 8% |
* Commodities added to the IOLR inventory. Currently not available locally in Israel.
Further breakdown of the four designated dietary formulations is as follows, based in the main on protein/oil variations.
| I B - IM - 2 74/76 (48 % protein) 5 % fish hydrolysate → 8 % oil added (6 % fish; 2 % soy) | II B - IM - 3 74/76 (48 % protein) 5 % fish hydrolysate → 10 % oil added (8 % fish; 2 % soy) Rice gel reduced to 10 % |
| III B - IM - 4 74/76 → (53 % protein; 8 % oil) Replace meat meal with 15 % FPC; 2 % liver concentrate; rice gel at 10 % 5 % fish hydrolysate | IV B - IM - 5 74/76 ( 53 % protein; 8 % oil) → No fish hydrolysate, increase fish meal to 53 % add 2 % wheat starch |
The four formulations can be compared as follows:
Comparison of I vs II: protein constant at 48 %, fat varied from 8 to 10 %.
Comparison of I vs III: fat constant at 8 %, protein varied from 48 to 53 %
Comparison of III vs IV:fish hydrolysate compared with no hydrolysate; protein at 53 %, oil at 8 %.
In view of the need to have a ready commercial supply of a high protein fry diet, a salmon crumble formulation will also be evaluated as a standard maintenance diet for sea bream. As noted, it is essential to have properly sized particles available to the particular stage of growth of the fish. In all likelihood, a high protein ( >50 %)high fat (ca 8 – 12 %) formulation will be needed in the early stages of fry growth, at least to a 5 g size animal. Logistics in shipment of specialized diets from other countries (Sweden, Norway, France, etc) must be carefully evaluated.
