| Summary: | A dietary study was conducted to investigate the effect of partly substituted levels of fish meal in feed for <500 g turbot (Scophthalmus maximus Rafinesque 1810) on growth performance. The experimental diets were formulated to contain 53, 73 and 93 % fish meal protein and different levels of plant protein substitutes (wheat, corn gluten, soybean and canola meal) with three replicates for each diet. The fish (N = 252; initial mean weight ± SD,140 ± 37 g) were tagged with PIT and randomly distributed into 9 rearing tanks (1.47 m3) and handfed to satiation 6 days a week for a period of 138 days. The temperature and salinity level were kept at a constant level of (mean ± SD) 15.4 ± 0.6 °C and 21.4 ± 1.8 ‰, respectively. Weight development was significantly affected by the dietary treatments. Fish fed lower fish meal diets displayed a slower weight development throughout the entire experiment compared to fish fed the high fish meal diet. However, no significant differences were shown between dietary treatment groups for specific growth rate, feed conversion ratio, daily feed intake and total feed consumption. Results demonstrate that substitution of fish meal by plant protein raw materials down to 53 % fish meal does not affect growth of turbot < 500 g. Tilgangur tilraunarinnar var að kanna áhrif útskiptingar fiskimjöls fyrir plöntuhráefni á vöxt sandhverfu undir 500 g að þyngd. Þrjár gerðir tilraunafóðurs innihélt mismunandi hátt hlutfall fiskimjölis (93, 73 og 53 %) og mismunandi plöntu hráefni (hveiti, maís, soja og repju mjöl). Fóðurgerðir voru prófaðar í þrítekningu. Sandhverfur (N=252, upphafsþyngd ± SD, 140 ± 37 g) voru örmerktar og þeim dreift tilviljunarkennt í níu 1.47 m3 ker. Handfóðrað var til mettunar tvisvar á dag, 6 daga vikunnar yfir 138 daga tímabil. Vatnshiti (15.4 ± 0.6°C, meðaltal ± SD), selta (21.4 ± 1.8 ‰) og súrefni (101.7 ± 7.1 %) var mælt daglega og stillt eftir þörfum. Hlutfall fiskimjöls í fóðrinu hafði marktæk áhrif á þyngdarvöxt fisksins sem fór vaxandi með auknu ...
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