Untitled - CNR

Marine research at CNRboops and 5% mussels Mytilus galloprovincialis;Diet group II fed exclusivelyon fish B. boops over the whole feeding;Diet group III fed exclusively on musselsM. galloprovincialis. All the food furnishedto each experimental group referredexclusively to the edible part. The “wild”group used as control (6 animals), was sacrificedimmediately after capture, to providethe background of biochemical composition.Octopuses were fed once dailyand each day the food was provided ad libitumbetween h12.00 and h14.00; fish wasprovided frozen, without tails or heads, andin the case of crabs were served alive andthe edible fraction was estimated as 50%including legs. Mussels too were servedalive. The feeding rate was 7% of the totalweight of the animals in each cage andvaried as a function of the animal’s weightthroughout the experimental period.The uneaten food was removed from eachcage the following day and dried, usingadsorbent paper, before being weighed tocalculate, by difference, the exact amountof food eaten. All samples of O. vulgariswere weighed once a week for adjustingthe amount of food provided. Mortalityand water quality parameters wererecorded daily.At the end of the experiment all sampleswere weighed (Wf=final weight in g). Thefollowing indexes were determined: Absolutegrowth rate AGR= (Wf-Wi)/t; Specificgrowth rate SGR = (LnWf-LnWi)x100/t;Feed efficency FE= (Wf-Wi)x100/IF; Feedconversion rate FCR=IF (Wf-Wi); Absolutefeeding rate AFR= IF/t; where Wi=initial weight in g; Wf = final weight in g;t= time in days; IF=ingested food in grams.2.3 Biochemical compositionanalysis2.3.1 Sample preparationAt the end of the 30 days experiment, alloctopuses of each feeding type were usedfor biochemical composition analyses. Inparticular the arm muscle of all animalswere filleted, minced in small pieces andmixed until a homogeneous sample wasobtained.Protein content was measured, accordingto Bradford [21], in diluted homogenates,using the Bio-Rad protein determinationkit (Biorad@-500-0006). Bovine serumalbumin was used as a standard. Sampleswere read at 495 nm. Glycogen from thearm muscle was extracted in the presenceof sulfuric acid and phenol [22]. Sampleswere read at 490 nm.Total lipid content was determinedgravimetrically after the extractionwith a solvent mixture ofmethanol/chloroform/water 1:2:1 (v/v/v)following Folch method [23]. All analyseswere made in triplicate for each sample.Protein, carbohydrates and total lipids wereexpressed as mg/g of wet weight.Triacylglycerols (TAG) and total cholesterol(CL) were measured by the colorimetricenzymatic Trinder method [24], usinga commercial kit (SGM – Rome -Italy).Phospholipids (PL) were quantified by acolorimetric enzymatic method [25] with acommercial kit (SGM – Rome -Italy). Tryacylglicerols(TAG), phospholipids (PL)and cholesterol levels were expressed as apercentage of total lipids.All analyses were repeated three times, andthe results were expressed as mean values± standard deviation (SD).2033