Long-term protein and lipid growth of Atlantic ž / salmon Salmo salar fed diets with partial replacement of fish meal by soy protein products at medium or high lipid level

This study investigated long-term effects on nutrient digestibility and protein and lipid growth of soy protein and lipid levels used in commercial grower diets for Atlantic salmon. Two series of Ž . extruded diets were formulated to contain either 45% protein and 32% lipid medium fat or 40% Ž . protein and 39% lipid high fat . Each series consisted of six diets in which a soy protein source Ž . Ž . Ž . partially replaced low-temperature LT dried fish meal FM : FM only control , soy protein Ž . Ž concentrate SPC, 30% of crude protein, CP ; SPC added 0.2% DL-methionine 30% of CP, . Ž . Ž . Ž SPCqmet ; dehulled, defatted soybean meal HP-SBM, 20% of CP ; full-fat FF SBM 10% of . Ž . CP , and; defatted SBM 10% of CP . Each diet was fed to triplicate groups of 0.56-kg salmon kept in sea pens. The experiment lasted 235 days, during which the salmon reached 2.5 to 2.8 kg. Growth was slower in the FM-control and HP-SBM treatments than in the other treatments. The HP-SBM diet induced enteritis in the distal intestine of the salmon and, at day 215, the apparent digestibilities of nitrogen, lipid and energy were lower in the HP-SBM treatments than in all other treatments. Except a slightly reduced muscle protein concentration in the HP-SBM treatment, no effects of dietary soy were detected on final body composition. Salmon fed the high-fat diets ) Corresponding author. Tel.: q47-71-69-5314; fax: q47-71-69-5301. Ž . E-mail address: [email protected] T. Storebakken . 1 Present address: Trouw France, Le Pont de Pierre, 02140 Fontaine les Vervins, France. 0044-8486r01r$ see front matter q2001 Elsevier Science B.V. All rights reserved. Ž . PII: S0044-8486 00 00473-7 ( ) S. Refstie et al.rAquaculture 193 2001 91–106 92 reached on average 122 g higher final weight than those fed the medium-fat diets; however, 91 g of this was in the form of lipid, and corresponded with enlarged deposits of visible fat. q 2001 Elsevier Science B.V. All rights reserved.