Fat deposition and flesh quality in seawater reared, dietary fat levels and starvation

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1 Ž. Aquculture Ft deposition nd flesh qulity in sewter rered, triploid rown trout ž Slmo trutt/ s ffected y dietry ft levels nd strvtion C. Regost, J. Arzel,), M. Crdinl, M. Lroche c, S.J. Kushik d Fish Nutrition Lortory, Unite mixte INRA-IFREMER, Centre de Brest IFREMER, Plouzne, Frnce VPrGA, IFREMER, Nntes, Frnce c LEIMA, INRA, Nntes, Frnce d Fish Nutrition Lortory, Unite mixte INRA-IFREMER, Sint Pee-sur-NiÕelle, Frnce Received 3 April 2000; received in revised form 14 August 2000; ccepted 14 August 2000 Astrct Three isoproteic Ž crude protein content: 56%. diets with different ft levels Ž11%, 20%, nd 26%. were fed to triplicte groups of triploid rown trout Ž initil verge ody weight of 1.5 kg., rered in sewter. At the end of 3 months of feeding, fish fed the high-ft Ž HF. diet were split into two groups: triplicte group of fish received the low-ft diet nd nother triplicte group ws kept unfed for further 2-month period. Fish initilly fed the low-ft diet during the first period were continued to e fed the sme diet. Fish fed the medium-ft Ž MF. diet during period 1 were eliminted for period 2. At the end of ech period, comprtive whole ody nlyses, sensory nd instrumentl Ž texture nd colour. nlyses were mde on fresh nd smoked fillets. During the first period, incresing dietry ft level hd no significnt effect on growth or feed utilistion, ut incresed whole ody Ž 14.6% to 17.9%, on wet weight sis. nd muscle Ž8.3% to 11.0%. ft content. During the second period, the fish fed the low-ft diet hd similr growth performnce irrespective of previous nutritionl history, wheres strvtion led to significnt loss of weight nd fillet yield. Whole ody ft content did not differ etween groups Ž round 15%. t the end of period 2. In fish initilly fed the HF diet, oth strvtion nd feeding low-ft diet led to reduction in muscle lipid content. Sensory nlyses reveled few differences etween ) Corresponding uthor. Tel.: q ; fx: q Ž. E-mil ddress: jrzel@ifremer.fr J. Arzel r01r$ - see front mtter q 2001 Elsevier Science B.V. All rights reserved. Ž. PII: S

2 326 C. Regost et l.raquculture tretments, in terms of visul colour spects, for oth cooked nd smoked fillets t the end of period 1. A positive reltionship etween instrumentl colour nlyses Ž L ), ), ) vlues. nd dietry ft levels ws oserved, ut no difference ws oserved for instrumentl texture mesurements. At the end of period 2, significnt increse in prmeters of colour ws oserved in unfed fish. Although oth feed withdrwl nd feeding low-ft diet 2 months efore slughtering led to reduction in ft content, strvtion hd the disdvntge of leding to significnt weight loss. q 2001 Elsevier Science B.V. All rights reserved. Keywords: Slmo trutt; Dietry ft; Strvtion; Ft deposition; Sensory nlyses; Colour; Texture 1. Introduction Since the erly findings of Lee nd Putnm Ž on the eneficil effects of dietry ft in protein spring in slmonids, it hs ecome common prctice to use high-ft diets Ž Hillestd et l., There is evidence tht high dietry lipid levels increse ft deposition in fish nd lter flesh qulity in terms of freshness, storge stility, processing yields nd orgnoleptic nd physicl properties ŽSheehn et l., 1996; Gjedrem, 1997; Einen nd Skrede, According to species nd ge, ft depots cn e locted in different tissues or orgns Ž Corrze nd Kushik, nd ffect flesh qulity vrily. In slmonids, lipids locted in the viscerl cvity led to decresed slughter yield nd the prt of ft ccumulted in muscle my modify flesh qulity Ž Fuconneu et l., Studies with other slmonids hve shown tht nutritionl fctors such s dietry ft sources ŽThomssen nd Røsjø, 1989; Greene nd Selivonchick, 1990., ft levels ŽHillestd nd Johnsen, 1994; Bjerkeng et l., 1997; Hemre nd Sndnes, 1999., or vitmin E Ž Boggio et l., cn influence physicl nd orgnoleptic qulity. Since strvtion is known to induce ft moilistion ŽJeziersk et l., 1982; Tkeuchi nd Wtne, 1982., in recent yers, frmed slmon re occsionlly strved prior to slughter in order to stimulte lipid ctolism nd moilistion nd thus improve flesh qulity ŽBlokhus, 1986; Lie nd Huse, 1992; Bonnet et l., 1996; Einen et l., Sefrmed rown trout re of commercil interest in Frnce. Erlier studies hve evluted the effects of growth rtes Ž Buvineu et l., nd of dietry lipids ŽArzel et l., on flesh qulity. Post-mortem chnges in flesh qulity of rown trout hve lso een studied to some extent Ž Bonnet et l., 1996; Lroche et l., 1996,.. An increse in dietry lipid levels re known to improve protein utilistion in rown trout Ž Gudn et l., 1989; Arzel et l., s in mny other fish ŽLee nd Putnm, 1973; Alliot et l., 1979; Cho nd Kushik, Lipid-rich diets re lso known to depress the ctivities of enzymes involved in lipid synthesis in coho slmon ŽLin et l., 1977., Atlntic slmon Ž Arnesen et l., 1993., rinow trout Ž Alvrez et l., nd sess Ž Dis et l., The ims of this study were to evlute Ž. 1 the effects of different dietry ft levels nd Ž. 2 the effects of pre-slughter feeding procedures Ž strvtion or low-ft diet. in se rered rown trout on growth, chemicl composition, ft synthesis nd deposition, plsm metolites, nd sensory nd physicl flesh qulity.

3 2. Mterils nd methods 2.1. Experimentl diets C. Regost et l.raquculture Three isoproteic diets Ž crude protein: 56% of dry mtter. were formulted contining grded levels of fish oil to otin totl crude ft levels of 11%, 20%, nd 26%. Minerl nd vitmin mixes were dded to meet the requirements of mrine fish ŽKushik nd Cuzon, Bsed on formultions provided, extruded diets Ž 9-mm dimeter. were mnufctured y commercil feed compny ŽLe Gouessnt Aquculture, 29 Lmlle, Frnce.. Ingredient nd chemicl composition of the diets re reported in Tle Growth study The growth trils were conducted during Decemer 1997 to My 1998 in our experimentl se cge-culture fcility Ž SEMII, 29 Cmret sur Mer, Frnce.. Triplicte groups of 140 triploid ll-femle rown trout, Slmo trutt Žinitil verge ody weight: "17 g were llotted to ech of nine floting cges of 60 m. Ech diet ws rndomly ssigned to triplicte groups which were fed y hnd three times dy to Tle 1 Ingredient nd proximte composition of the experimentl diets Experimentl diets LF MF HF Ingredients (%) Norsemink fish mel Whole whet Whet gluten Fish oil Minerl nd vitmin premix Choline chloride c Fungini 2A d Rovimix sty C Chemicl composition Dry mtter wdm x Ž % Ash Ž % DM Crude ft Ž % DM Crude protein Ž % DM Energy Ž kjrg DM Norsemink, Norsildmel, Minde, Norwy. Minerl mixture in kg of diet: KCl, 90; KI, 0.04; CHPO4P2H 2O, 500; NCl, 40; CuSO4P5H 2O, 3; ZnSO4PH 2O, 4; CoSO4P7H 2O, 0.02; FeSO4P7H 2O, 20; MnSO4PH 2O, 3; CCO 3, 215; MgCO 3, 124; NF, 1. Vitmin mixture in mg or UIrkg of diet: retinyl cette, UI; choleclciferol, 1000 UI; ll-rc-tocopheryl cette, 40; mendione sodium isulfide, 1; thimin, 10; rioflvin, 25; D-clcium pntothente, 50; pyridoxine, 10; vitmin B 12, 0.06; nicin, 100; folic cide, 5; iotin, 1; myo-inositol, c Antifungl gent. d Ascorte polyphosphte, Hoffmnn LRoche.

4 328 C. Regost et l.raquculture visul stiety nd the feed mount distriuted ws recorded. Wter temperture ws recorded ech dy t depth of 2 m nd vried etween 98C nd 128C, while slinity remined constnt t 35. Ech tretment group ws weighed every 3 weeks to follow growth nd feed utilistion. At the end of n initil growth period lsting 12 weeks, fish fed the HF diet were split into two groups of 60 fish: triplicte group of fish received the low-ft diet ŽLF X. nd the other triplicte group ws kept unfed for further pre-hrvest period of 8 weeks Ž period 2.. Fish initilly fed the low-ft Ž LF. diet during the first period were continued to e fed with the sme diet ut the numer of fish ws reduced to 60 fish per cge. Fish fed the medium-ft Ž MF. diet during period 1 were eliminted for period Smplings At the eginning of the growth study, representtive smple of 14 fish from n initil pool ws withdrwn nd stored t y208c for nlyses of whole ody composition. At the end of ech period, the sme protocol of slughter ws strictly followed for ech group. Fish were fsted for 2 dys efore slughter. Thirteen fish from ech cge were stunned with thick round rod on the hed, led in cold sewter with ice nd covered with ice efore dissection. Gutting nd filleting were relised within 30 min to 1 h fter slughter when fish were still in pre-rigor stte. Five whole fish per cge were smpled for whole ody composition nlyses Ž wter, sh, protein, ft nd energy. nd nutrient retention clcultion. Eight fish per cge were withdrwn to weigh the liver nd the digestive trct Ž including viscerl ft. for clculting heptosomtic index Ž HSI. nd viscerosomtic index Ž VSI. nd for the following nlyses: three fish for sensory nlyses Ž left fillet smoked nd right fillet cooked., three fish for instrumentl nlyses of texture nd colour Ž left fillet cooked nd right fillet rw., nd finlly, two fish were withdrwn for lipid nlyses in muscle Ž left whole fillet.. On six fish from ech tretment group, liver nd viscer were nlysed for totl lipids nd heptic ctivities of glucose-6-phosphte dehydrogense Ž G6PD, EC nd ftty cid synthetse Ž FAS, EC Whole muscles nd orgns for lipid nlyses were frozen in liquid nitrogen nd stored t y808c. Immeditely upon cpture nd stunning, lood smples Ž 2 ml. were withdrwn y crdic puncture from 13 fish per replicte cge using heprinised syringes. After centrifugtion Ž 1200 = g, 10 min, 58C., plsm ws seprted nd stored frozen t y208c s seprte liquots for nlyses of triglyceride nd totl cholesterol concentrtions Anlyticl methods Proximte composition of diets nd chemicl composition of whole ody nd tissues were determined y the following stndrd procedures Ž AOAC, 1984.: dry mtter fter desicction in n oven Ž 1058C for 24 h., sh comustion Žincinertion t 5508C for 12 h., crude protein Ž Dums, nitrogen nlyser, Fisons instrument, N = 6.25., crude ft Ž dichloromethne extrction y Soxhlet s method. nd gross energy ŽIKA ditic clorimeter C4000A.. Plsm totl cholesterol concentrtions nd plsm triglyceride

5 C. Regost et l.raquculture concentrtions were determined using commercil kits ŽBoehringer no , Mnnheim, Germny nd iomerieux no. PAP150, Frnce, respectively.. For lipid nlyses of tissues, extrction ws done ccording to Folch et l. Ž 1957., chloroform eing replced y dichloromethne Ž Chen et l., For ssys of heptic lipogenic enzyme ctivities, liver smples were homogenised in three volumes of ice-cold uffer Ž0.02-M Tris HCl, 0.25-M sucrose, 2-mM EDTA, 0.1-M sodium fluoride, 0.5-mM phenylmethylsulphonylfluoride, 0.01-M -mercptoethnol, ph 7.4. nd the homogentes were centrifuged t =g t 48C for 20 min. Solule protein content of liver homogentes ws determined y the method of Brdford Ž using ovine serum lumin s the stndrd. Enzyme ctivities were ssyed on superntnt frctions ccording to Butist et l. Ž for the G6DP nd ccording to Hsu et l. Ž for FAS. Enzyme ctivity units Ž IU. defined s micromol sustrte converted to product per minute t ssy temperture Ž 308C., were expressed either per milligrm heptic solule protein or per grm liver tissue Ž wet weight Flesh qulity eõlution Sensory profiling Ž Stone et l., 1974; ISO ws performed on cooked nd smoked fillets y trined internl sensory pnel Ž IFREMER, Nntes, Frnce. consisting of 20 individuls selected for their interest, vilility, nd sensoril cpcities of memorising stimuli or discriminting intensities. All were volunteers nd received regulr trining sessions to develop their sensory performnces nd knowledge of mrine products. Sessions were conducted in n ir-conditioned room designed for sensory nlysis divided into 10 individul oxes with stndrdised light Ž T s 6500 K. nd equipped with computerised system Ž Fizz, Biosystemes, ` Dijon.. These conditions were conducive to concentrtion nd voided communiction etween ssessors nd disturnce y externl fctors Ž AFNOR, The rw smples Žcoming from the middle prt of fillet. were cooked for 2.5 min in microwve oven ŽPnsonic NN8550, 850 W. in closed owl efore nlyses nd the smoked fillets Žtrditionl smoking: slting during 3.5 h t 108C, drying during 2 h t 208C nd smoking during 6 h t 208C. were sliced nd kept t mient temperture. Products were ssigned three-digit numers, rndomised nd served simultneously. The smples were evluted using continuous scle presented on computer screen from 0 Ž low intensity. to 10 Žhigh intensity. for the following ttriutes: intensity nd slmonid odour, pink colour, visul compct spect, slty flvour, intensity of flvour, firmness, smooth, ft nd dmp Ž impression of moisture. texture nd exudtion Ž corresponding to loss of wter. for cooked fillet nd smoky nd slmonid odour, pink nd ornge colour, colour homogeneity, slty flvour, slty nd smoky ftertste, firmness nd ft texture for smoked fillet Ž see Tles 6 nd 7.. The odour ttriutes were ssessed immeditely fter opening the owl, while flvour nd texture in mouth were evluted fter cutting the smples. The dt were immeditely trnsferred y the network to centrl computer for sttisticl processing. Instrumentl colour nd texture nlyses were performed 7 dys fter slughter on fillets kept in ice in vcuum seled pcking fter threding nd were done on rw nd cooked Ž 1 h t 708C in doule oiler in vcuum seled pcking. fillets. For texture,

6 330 C. Regost et l.raquculture Krmer sher press Ž 64=64 mm. ws used with compression up to reking using universl testing mchine Ž INSTRON, model with lod cell of 5 kn nd during this test t constnt speed of 1 mmrs into the fillets. Smples were tken from the nterior prt of flesh Ž corresponding pproximtely to the prt used in sensory nlyses. nd mesured 64-mm long nd fillet size in width. For ech smple, the weight ws recorded to clculte the specific resistnce expressed s mximl force divided y smple weight Ž Szczesnick et l., Instrumentl colour nlysis of fillets ws mde with Dr. Lnge colorimeter using light source D65 nd 108-oserver ngle. Mesures were mde on the internl prt of rw fillet nd on cooked minced flesh. Dt were expressed in L ) ) ) system, representing lightness, redness, nd yellowness, respectively, s recommended y CIE Ž The instrumentl nlyses were performed ccording to the procedures descried y Lroche et l. Ž Sttisticl nlysis All dt except sensory nlyses were sujected to one-wy nlysis of vrince to test the effects of experimentl diets. In cses where significnt differences occurred Tle 2 Growth performnce, feed, nd protein efficiency in rown trout t the end of the two growth periods 1 Period 1 Experimentl diets LF MF HF IBW Ž. g " " "14 FBW Ž. g " " "39 4 K 1.42" " " SGR 0.66" " " FE 0.80" " " PER 1.42" " "0.03 X Ž. Ž. Period 2 LF Unfed HF LF HF IBW Ž. g 2511" " "53 FBW Ž. g 3018" " "29 K 1.47" " "0.03 SGR 0.33"0.01 y0.15" "0.03 FE 0.56" "0.04 PER 0.99" "0.08 Vlues re mens"stndrd devitions Ž ns3.. Vlues in the sme row with different superscripts re significntly different Ž P Period 1 corresponds to n initil durtion of 12 weeks during which fish were fed different dietry ft levels. Period 2 corresponds to nother 8 weeks during which fish fed the HF diet were susequently either kept unfed or fed the LF diet. 2 IBWsinitil ody weight. 3 FBWsfinl ody weight. 4 K, condition fctorsžfbwrlength SGR, specific growth rtes100 ŽŽ ln FBWyln IBW. rdys.. 6 FE, feed efficiency s100 Ž wet weight ginrdry feed intke.. 7 PER, protein efficiency rtios100 Ž wet weight ginrcrude protein intke..

7 C. Regost et l.raquculture Ž significnce level , the mens were compred using Student Newmn Keuls test. The sttisticl tests were performed using the STAT-ITCF Ž ITCF, softwre. The results of sensory nlyses were sujected to two-wy nlysis of vrince to test the effects of experimentl diets nd ssessors. In cses where significnt differences occurred, the mens were compred using Duncn test with the FIZZ, Biosystemes ` softwre. 3. Results 3.1. Growth performnce nd whole ody composition During the first 3 months Ž period 1., growth performnce were high for ll fish with no differences etween the groups Ž Tle 2.. A slight ut not significnt increse in growth rte ws oserved with incresed dietry ft levels. No significnt differences were found mong tretments for condition fctor Ž K., feed efficiency Ž FE., nd protein efficiency rtio Ž PER.. Concerning whole ody composition of fish fed during period 1, higher contents of dry mtter, ft, nd gross energy were oserved in fish fed higher dietry ft levels Ž Tle 3.. Whole ody protein content of fish fed the HF diet ws significntly lower thn protein content of fish fed the two other diets. A significntly lower HSI ws found in fish fed the HF diet compred to fish fed LF nd MF diets. The VSI did not differ etween tretments. Tle 3 Ž. 1 Whole ody composition % wet weight, HSI nd VSI of rown trout t the end of the two growth periods Period 1 Experimentl diets Initil LF MF HF Wter Ž % " " "0.6 Ash Ž % " " "0.1 Protein wn=6.25 x Ž % " " "0.4 Ft Ž % " " "0.5 Energy Ž kjrg " " "0.2 HSI Ž %. 1.3" " "0.0 VSI Ž %. 7.8" " "0.2 X Ž. Ž. Period 2 LF Unfed HF LF HF Wter Ž %. 63.7" " "0.1 Ash Ž %. 1.9" " "0.1 Protein wn=6.25 x Ž %. 19.3" " "0.1 Ft Ž %. 15.5" " "0.4 Energy Ž kjrg. 10.3" " "0.2 HSI Ž %. 1.1" " "0.0 VSI Ž %. 6.6" " "0.2 Vlues re mens"stndrd devitions Ž ns3.. Vlues in the sme row with different superscripts re significntly different Ž P See footnote 1 of Tle 2 for description of periods.

8 332 C. Regost et l.raquculture During period 2, the growth performnce ws similr for the two groups ŽLF nd LF X. fed the low-ft diet Ž Tle 2., wheres fish kept unfed lost weight nd their condition fctor decresed significntly Ž P FE nd PER were not different Ž P)0.05. etween the two groups of fed fish. At the end of period 2, dry mtter, sh, ft nd gross energy content were not ffected y tretments Ž Tle 3.. A significnt Ž P decrese of protein content of whole fish ws oserved in unfed fish. Ft content of whole fish in period 2 ws lower thn ft content in period 1. Strvtion led to decrese in HSI in comprison to those of fed fish Nutrient utilistion Ž. Dily protein gin ws not significntly different etween tretments Fig. 1. Dily whole ody ft gin incresed with incresing dietry ft levels. During period 2, Fig. 1. Dily protein nd ft gin in rown trout. Error rs re stndrd devitions Ž ns3.. Different superscripts re significntly different Ž P ABW: verge ody weight: Ž IBWqFBW. r2.

9 C. Regost et l.raquculture X significnt ody protein nd ft loss occurred in unfed fish Ž Fig. 1.. For fish of LF groups Ž trnsferred from HF diet to low-ft diet., dily protein gin ws similr to the LF group nd dily ft gin ws just elow zero nd significntly different from LF nd unfed groups LiÕer, Õiscer, nd muscle composition In period 1, liver moisture nd ft contents were not significntly ffected y dietry ft levels Ž Tle 4.. Heptic ft content vried etween 8.7% nd 9.9% Žin wet weight sis.. Viscerl ft content vried etween 38% nd 47% nd fish fed the HF diet hd significntly Ž P higher ft deposition. In period 1, muscle ft content incresed nd vried etween 8.3% nd 11.0% nd the vlues of fish fed the LF diet were significntly different from those of fish fed the diets MF nd HF. During period 2, withdrwl of feed did not ffect liver composition Ž Tle 4.. Dry mtter nd ft content of viscer were significntly lower in fish fed the LF diet thn unfed fish or in fish Tle 4 Moisture nd totl lipid content Ž % wet weight. of liver, viscer, nd muscle in rown trout t the end of the two growth periods 1 Period 1 Experimentl diets LF MF HF LiÕer Moisture 68.0" " "0.5 Totl lipid 9.9" " "0.7 Viscer Moisture 44.0" " "2.8 Totl lipid 37.9" " "1.8 Muscle Moisture 69.0" " "0.5 Totl lipid 8.3" " "0.6 X Ž. Ž. Period 2 LF Unfed HF LF HF LiÕer Moisture 71.7" " "0.8 Totl lipid 6.2" " "0.7 Viscer Moisture 45.3" " "1.9 Totl lipid 38.2" " "1.5 Muscle Moisture 67.9" " "0.7 Totl lipid 8.8" " "0.8 Vlues re mens"stndrd devitions Ž ns6.. Vlues in the sme row with different superscripts re significntly different Ž P See footnote 1 of Tle 2 for description of periods.

10 334 C. Regost et l.raquculture previously fed the HF diet Ž P Although moisture content of muscle incresed in unfed fish, this hd no significnt effect on ft content Plsm cholesterol nd triglycerides At the end of the first period, plsm cholesterol concentrtions incresed with incresing dietry ft levels nd were higher in fish fed diets MF nd HF Ž Fig. 2.. In period 2, significnt decrese in plsm cholesterol concentrtion ws oserved for fish kept unfed Ž Fig. 2.. Plsm triglyceride concentrtions showed no differences etween tretments in oth periods. Fig. 2. Plsm totl cholesterol nd triglyceride concentrtions of rown trout. Error rs re stndrd Ž. Ž. devitions ns13. Different superscripts re significntly different P

11 C. Regost et l.raquculture Tle 5 Activities of G6PD nd FAS in the liver of rown trout t the end of the two growth periods 1 Period 1 Experimentl diets LF MF HF G6PD IUrg liver 23.54" " "0.68 IUrmg protein 0.50" " "0.01 FAS miurg liver 3.19" " "0.32 miurmg protein 0.08" " "0.01 X Ž. Ž. Period 2 LF Unfed HF LF HF G6PD IUrg liver 19.28" " "1.60 IUrmg protein 0.33" " "0.03 FAS miurg liver 2.33" " "0.18 miurmg protein 0.04" " "0.01 Vlues re mens"stndrd devitions Ž ns6.. Vlues in the sme row with different superscripts re significntly different Ž P See footnote 1 of Tle 2 for description of periods ActiÕities of lipogenic enzymes At the end of period 1, the ctivity of heptic G6PD in fish fed the low-ft diet ws significntly lower thn those of fish fed MF nd HF diets Ž Tle 5.. Heptic FAS ctivities were low nd showed similr trend lthough without significnt differences. At the end of period 2, oth enzyme ctivities were found to e significntly lower Ž P in unfed fish s compred to fed fish Gutted nd fillet yields During period 1, there ws no significnt effect Ž P) of dietry ft levels on gutted nd fillet yield Ž Fig. 3.. At the end of period 2, gutted yield did not differ etween tretments Ž Fig. 3.. Fillet yield of unfed fish ws significntly lower Ž P thn the two groups of fish fed the LF diet Ž Fig Sensory nlyses Ž. Sensory nlyses were performed on cooked nd smoked fillets Tle 6. No fillets were rejected y the sensory pnel. At the end of period 1, few differences were

12 336 C. Regost et l.raquculture Fig. 3. Gutted wgutted yieldsgutted crcss weightrfish weightxž. nd fillet wfillet yieldsfillet weightrgutted fish weightx Ž. yields in rown trout. Error rs re stndrd devitions Ž ns9.. Different superscripts re significntly different Ž P oserved for cooked fillets. Only compctness ws significntly different, fillets from fish fed the HF diet presenting the lowest vlue. At the end of period 1, slty flvour nd slty ftertste in smoked fillets of fish fed the low-ft diet seemed to e significntly higher thn in the other groups Ž P At the end of period 2, cooked fillets from unfed fish versus fed fish were significntly different in terms of colour nd texture in mouth Ž Tle 7.. Intensity of red colour ws more pronounced nd fillets ppered more smooth nd dmp in unfed group. Cooked fillets from fish fed the low-ft diet during the whole tril hd firmer texture nd lower exudtion thn the other groups Ž P In smoked fillets, strvtion did not ffect sensory chrcteristics. Only slight tendency of more yellowness nd less of redness ws noted in fillets from fish kept unfed for 2 months.

13 C. Regost et l.raquculture Tle 6 Ž. 1 Sensory nlyses scores of 1 to 10 of rown trout t the end of period 1 Experimentl diets ANOVA Ž p. LF MF HF Cooked fillet Odour intensity Slmonid odour Pink colour Compct spect Flvour intensity Slty flvour Firmness Smooth texture Dmp texture Ft texture Exudtion Smoked fillet Smoky odour Slmonid odour Pink colour Ornge colour Colour homogeneity Slty flvour Slty ftertste Smoky ftertste Firmness Ft texture Vlues in the sme row with different superscripts re significntly different. 1 See footnote 1 of Tle 2 for description of periods Instrumentl colour nlysis Ž ) ) After period 1, higher vlues for ll prmeters of colour L s lightness, s ) redness, nd s yellowness. were oserved in fish fed MF nd HF diets prticulrly in uncooked fillets Ž Tle 8.. On cooked fillets, only C ) Ž sturtion. vlues presented significnt difference etween tretments. Strvtion induced n intensifiction of colour. Vlues of C ), ), nd ) were significntly higher in unfed fish thn the others in oth rw nd cooked fillets Ž P In fish fed the low-ft diet only in Ž X. ) ) period 2 group LF, the vlues of L nd of rw fillets were significntly different from those of fish fed the LF diet during the whole study. Instrumentl colour nlysis did not show ny differences etween cooked fillets from the two groups ŽLF nd LF X. fed the low-ft diet during the finishing period Instrumentl texture nlyses No significnt effects of dietry ft levels were oserved for ny of the prmeters of Ž. instrumentl texture nlyses on rw or cooked fillets t the end of period 1 Tle 9.

14 338 C. Regost et l.raquculture Tle 7 Ž. 1 Sensory nlyses scores of 1 to 10 of rown trout t the end of period 2 Experimentl diets ANOVA Ž p. X Ž. Ž. LF Unfed HF LF HF Cooked fillet Odour intensity Slmonid odour Pink Colour Compct spect Flvour intensity Slty flvour Firmness Smooth texture Dmp texture Ft texture Exudtion Smoked fillet Smoky odour Slmonid odour Pink colour Ornge colour Colour homogeneity Slty flvour Slty ftertste Smoky ftertste Firmness Ft texture Vlues in the sme row with different superscripts re significntly different. 1 See footnote 1 of Tle 2 for description of periods. At the end of the study, mximl force of rw fillets ws significntly higher for fish kept unfed thn fed fish. The work expressed s mjrg ws lower for fish fed the HF diet during period 1 nd then switched to the LF diet in period 2 ŽLF X. thn in the two other groups. No differences etween tretments were oserved for mximl force of cooked fillets. 4. Discussion The growth rte of fish in this study ws higher thn those reported y Arzel et l. Ž for rown trout of similr size grown over the sme seson Ž winter.. Incresed dietry ft levels were found to improve feed nd protein utilistion in rown trout y Gudn et l. Ž nd Arzel et l. Ž Present dt do not revel ny significnt difference in FE etween tretments; since it is difficult to record feed intke under cge culture conditions, there might hve een some feed losses, despite which vlues for FE were very good. Withdrwl of feed for 2 months prior to slughter led to significnt

15 C. Regost et l.raquculture Tle 8 Prmeters of instrumentl colour nlyses of rown trout fillets t the end of the two growth periods 1 Period 1 Experimentl diets LF MF HF Rw fillet ) 2 L 43.8" " "0.4 ) " " "0.2 ) " " "0.2 ) 5 C 21.7" " "0.3 ) 6 H 37.8" " "0.2 Cooked fillet ) L 75.5" " "0.3 ) 19.0" " "0.4 ) 17.3" " "0.2 ) C 25.7" " "0.5 ) H 42.3" " "0.2 X Ž. Ž. Period 2 LF Unfed HF LF HF Rw fillet ) c L 40.6" " "0.2 ) c 16.7" " "0.3 ) 12.2" " "0.3 ) C 20.7" " "0.4 ) H 36.1" " "0.2 Cooked fillet ) L 73.9" " "0.3 ) 20.3" " "0.3 ) 18.5" " "0.2 ) C 27.5" " "0.5 ) H 42.4" " "0.2 Vlues re mens"stndrd devitions Ž ns9.. Vlues in the sme row with different superscripts re significntly different Ž P See footnote 1 of Tle 2 for description of periods. 2 L ) : lightness. 3 ) : Redness. 4 ) : Yellowness. 5 ) C : Sturtions6Ž ) 2 q ) ) Ž. Ž ) H : Hues 180rp Arctn r ).. weight loss here s in studies with other slmonids ŽTkeuchi nd Wtne, 1982; Lie nd Huse, 1992; Einen et l., However, ody length did not chnge significntly in unfed fish contrry to oservtions of Bonnet et l. Ž in rown trout. Lie nd Huse Ž showed tht ody length of Atlntic slmon incresed in fish strved 35 nd 78 dys. Einen et l. Ž found tht ody length did not chnge significntly in Atlntic slmon strved for 30 dys or less nd incresed in those strved eyond 58 dys. Initil condition fctors Ž K. of fish s well s possile sesonl influences might possily explin such differences.

16 340 C. Regost et l.raquculture Tle 9 Prmeters of instrumentl texture nlyses of rown trout t the end of the two growth periods 1 Period 1 Experimentl diets LF MF HF Rw fillet Mx. force Ž Nrg. 6.3" " "0.3 Work Ž mjrg. 76.7" " "3.9 Cooked fillet Mx. force Ž Nrg. 30.7" " "0.9 Work Ž mjrg " " "12.5 X Ž. Ž. Period 2 LF Unfed HF LF HF Rw fillet Mx. force Ž Nrg. 6.1" " "0.3 Work Ž mjrg. 98.3" " "3.2 Cooked fillet Mx. force Ž Nrg. 27.3" " "1.6 Work Ž mjrg " " "14.1 Vlues re mens"stndrd devitions Ž ns9.. Vlues in the sme row with different superscripts re significntly different Ž P See footnote 1 of Tle 2 for description of periods. The increse in whole ody ft deposition with the increse of dietry ft levels s oserved here re in ccordnce with erlier dt from rown trout Ž Arzel et l., s well s those from other species: Atlntic slmon ŽHillestd nd Johnsen, 1994; Bjerkeng et l., 1997; Hemre nd Sndnes, 1999., rinow trout ŽStorekken nd Austreng, 1987; Alvrez et l., 1998., sess Ž Alliot et l., or gilthed serem Ž Vergr et l., At the end of period 2, lthough unfed fish hd lower liver size Ž HSI., neither strvtion nor switch to low-ft diet of fish initilly fed with the high-ft diet led to decrese in VSI. A reduction in muscle ft ws however oserved in these fish. These results differ from those of Jeziersk et l. Ž nd of Storekken et l. Ž in rinow trout where viscer nd liver were found to e more susceptile to ft moilistion thn crcss nd muscle. In Atlntic slmon, the viscerl ft content stys stle during strvtion of 3 86 dys Ž Einen et l., In the present study, reduction in whole ody protein content ws much lower Ž 5%. thn tht in lipid content Ž 12%., suggesting tht t lest under the conditions previling, rown trout could etter conserve their protein thn lipid when kept unfed. Bsed on the respective chnges in gross energy nd totl nitrogen in unfed fish, the contriution of protein for energy purposes ppers to rnge from 2.0 to 3.4 mgnrkj, vlues comprle to those found in other species ŽKushik nd Luquet, 1977; Kushik nd Medle, The slight differences in ody composition of fish mintined under the low-ft dietry tretment t the end of the two periods possily reflect chnges occurring with incresing ody size.

17 C. Regost et l.raquculture Plsm cholesterol concentrtions were comprle to vlues found in rinow trout Ž Alexis et l., 1985; Kushik et l., According to Fremont nd Leger Ž 1981., plsm cholesterol concentrtions depend on the nutritionl sttus. Kushik et l. Ž oserved tht soy protein hd possile hypocholesterolemic effect. In Atlntic slmon fed different dietry ft levels, Hemre nd Sndnes Ž found no chnges in plsm cholesterol or triglyceride levels. Strvtion induced decrese of plsm cholesterol concentrtions s in rinow trout where strvtion ws ccompnied y significnt decreses in serum glucose nd lood cholesterol concentrtions reflecting decrese in feed intke or n increse in generl lipid metolism Ž Heming nd Pleczny, Lipogenic processes in fish re similr to those in mmmls Ž Iritni et l., The heptic tissue is recognised s the preferentil site of de novo ftty cid synthesis in fish Ž Lin et l., 1977; Srgent et l., Dietry non-protein energy sources re known to ffect G6PD, mlic enzyme nd FAS ctivities in rinow trout, chnnel ctfish, nd Europen sess ŽLin et l., 1977,; Likimni nd Wilson, 1982; Arnesen et l., 1993; Alvrez et l., 1998; Dis et l., The vlues of G6PD ctivities in rown trout s found here were similr to those recorded in rinow trout ŽBrroso et l., 1994; Alvrez et l., 1998; Dis et l., The decrese in G6PD ctivities with incresing dietry ft levels reflects most resonly the effects of the concomitnt decrese in dietry crohydrte levels. The sence of significnt chnges in the ctivities of FAS with increse in dietry ft levels is lso noteworthy nd corresponds well with lck of significnt differences in overll dily ft gin. The decrese in G6PD nd FAS ctivities oserved in unfed rown trout possily results from chnge in metolic flux s seen in other species Ž Lin et l., 1977; Brroso et l., Even with the ccumultion of periviscerl ft Ž Tle 4., there ws no reduction in gutted yield, the vlues of which s oserved here re in the rnge of vlues found in other slmonids Ž Einen et l., 1998; Hillestd et l., In Atlntic slmon, strvtion increses the slughter yield Ž Lie nd Huse, 1992; Einen et l., 1998., wheres our dt suggest only slight ut not significnt increse. However, the decrese in fillet yield under unfed conditions ws lso oserved in Atlntic slmon Ž Einen et l., Among the most importnt qulity ttriutes of niml or fish products from consumer s point of view re sensory ttriutes such s colour, texture, odour nd flvour Ž Boggio et l., Sensory ssessment showed no cler differences etween groups except tht smoked fillet of fish fed the low-ft diet hs less ft nd judged s more slty fter smoking. Strvtion induced modifictions on sensory prmeters such s smooth nd dmp texture nd colour intensity confirmed y the instrumentl colour nlyses. In rinow trout, strvtion of 1 or 2 months did not significntly ffect the odour or tste of cooked fillets Ž Johnsson nd Kiessling, Einen nd Thomssen Ž found tht strvtion decresed the fresh flvour of cooked fillets of Atlntic slmon. These results show tht the currently ville dt on sensory nlyses re it contrdictory nd suggest tht, t lest, stndrdistion of methodologies would e most useful. In slmonids, flesh colour is n importnt prmeter of qulity for the consumers conferring n «elite» imge to these fish. Incresing dietry ft levels induced n intensifiction of colour of fillets, prticulrly of rw fillets. Vlues of sturtion C ) increse with the increse of white muscle pigment concentrtion Ž Chouert,

18 342 C. Regost et l.raquculture Better pigmenttion with n increse of dietry ft levels hs lredy een found in rinow trout Ž Torissen, 1985; Chouert et l., nd in Atlntic slmon ŽBjerkeng et l., 1997; Einen nd Roem, 1997; Einen nd Skrede, In Atlntic slmon, Einen nd Skrede Ž found tht incresing ft levels of the fillets significntly incresed redness Ž ). nd yellowness Ž ). vlues of the rw fillets. Also, Nickell nd Bromge Ž found in rinow trout tht lightness Ž L ). vlues were significntly correlted with flesh lipid content when dietry lipid level incresed from 8% to 27%. Whether the increse in vlues of colour prmeters oserved in unfed fish re due to n internl redistriution of the pigment in fillets in the sence of dietry pigment intke Ž Chouert, is lso worth investigting, especilly since there ws significnt drop in muscle lipid content of fish fter 2 months of fsting. Given tht texture is multiple prmeter ttriute Ž Sigurgisldottir et l., 1997., we employed different prmeters like mximl force nd work. Chnges in dietry ft levels did not cuse ny noticele difference in the prmeters of instrumentl texture evlution, neither of cooked fillets nor of rw fillets. Very erly, it ws suggested tht when ft content in muscle is high, texture of the fillet ecomes more tender ŽDunjski, Kuniski et l. Ž lso found reltion etween ft content nd muscle hrdness in horse mckerel. In rinow trout, while prmeters of texture of rw fillet re conditioned y flesh ft content, those of cooked fillets re independent of ft content Ž Fuconneu et l., In fsted rown trout, n increse in mximl force ws oserved. After long-term strvtion, n increse in ph Ž t dy 4 nd 12. nd in hrdness of muscle texture hs een oserved in Atlntic slmon ŽEinen nd Thomssen, In the present study, the hrdness of cooked fillets ws significntly higher only in rown trout fed the low-ft diet during the whole study. This effect is proly due to different lipid distriution in muscle rther thn overll muscle lipid content. In conclusion, high dietry ft levels led to incresed lipid deposition in the whole ody nd muscle of rown trout s in other slmonids. Both feeding low-ft diet or feed withdrwl for 2 months prior to slughter led to reduction in whole ody s well s muscle ft content, without however hving cler effect on the sensory qulity of flesh. However, compred to fsting, feeding low-ft diet hs the definite dvntge of conserving growth performnce. Acknowledgements The uthors would like to express their grtitude to the personnel of the SEMII experimentl sttion of Cmret nd to Herve Le Delliou for his technicl ssistnce for chemicl nlysis. C. Regost is recipient of prtil finncil scholrship from Region Bretgne. References AFNOR, Directives generles pour l implnttion de locux destines ` l nlyse sensorielle ŽNF V Controle ˆ de l Qulite des Produits Alimentires, Anlyse Sensorielle. 5eme ` edn. AFNOR, pp , Pris L Defense.

19 C. Regost et l.raquculture AOAC Ž Assocition of Officil Anlyticl Chemists., Officil Methods of Anlysis. 12th edn. Assocition of Officil Anlyticl Chemists, Wshington, DC, USA, 1141 pp. Alexis, M.N., Ppprskev-Ppoutsoglou, E., Theochri, V., Formultion of prcticl diets for rinow trout Ž Slmo girdneri. mde y prtil or complete sustitution of fishmel y poultry y-products nd certin plnt y-products. Aquculture 50, Alliot, E., Pstoureud, A., Nedellec, J., Etude de l pport clorique et du rpport clorico-zote dns l limenttion du r Dicentrrchus lrx. Influence sur l croissnce et l composition corporelle. In: Hlver, J.E., Tiews, K. Ž Eds.., Proc. World Symp. on Finfish Nutrition nd Fishfeed Technology, Hmurg, Germny Heenemnn, Berlin, vol. I, pp Alvrez, M.J., Lopez-Bote, C.J., Diez, A., Corrze, G., Arzel, J., Dis, J., Kushik, S.J., Butist, J.M., Dietry fish oil nd digestile protein modify susceptiility to lipid peroxydtion in the muscle of rinow trout Ž Oncorhynchus mykiss. nd se ss Ž Dicentrrchus lrx.. Br. J. Nutr. 80, Arnesen, P., Krogdhl, A., Kristinsen, I.O., Lipogenic enzyme ctivities in liver of Atlntic slmon Ž Slmo slr.. Comp. Biochem. Physiol. 105B, Arzel, J., Mrtinez Lopez, F.X., Metiller, R., Stephn, G., Viu, M., Gndemer, G., Guillume, J., Effect of dietry lipid on growth performnce nd ody composition of rown trout Ž Slmo trutt. rered in sewter. Aquculture 123, Brroso, J.B., Grci-Slguero, L., Pergon, J., de l Higuer, M., Lupinez, J.A., Effects of long term strvtion on the NADPH production systems in severl different tissues of rinow trout ŽOncorhynchus mykiss.. In: Kushik, S.J., Luquet, P. Ž Eds.., Fish Nutrition in Prctice. Birritz, Frnce, pp , INRA Editions. Les Colloques no. 61. Brroso, J.B., Grci-Slguero, L., Pergon, J., de l Higuer, M., Lupinez, J.A., The influence of dietry protein on the kinetics of NADPH production systems in vrious tissues of rinow trout Ž Oncorhynchus mykiss.. Aquculture 124, Butist, J.M., Grrido-Pertierr, A., Soler, G., Glucose-6-phosphte dehydrogense from Dicentrrchus lrx liver: kinetic mechnism nd kinetic of NADPH inhiition. Biochim. Biophys. Act 967, Buvineu, C., Lroche, M., Heil, F., Dumont, J.P., Crdinl, M., Cornet, J., Vllet, J.L., Fuconneu, B., Fure, A., Incidence de l vitesse de croissnce sur les crcteristiques de l chir de l truite frio Ž Slmo trutt. elevee en mer. Sci. Aliment. 13, Bjerkeng, B., Refstie, S., Fjlestd, K.T., Storekken, T., Rødotten, M., Roem, A.J., Qulity prmeters of the flesh of Atlntic slmon Ž Slmo slr. s ffected y dietry ft content nd full-ft soyen mel s prtil sustitute for fish mel in the diet. Aquculture 157, Blokhus, H., Aspects relted to qulity of frmed slmon Ž Slmo slr.. In: Krmer, D.E., Liston, J. Ž Eds.., Sefood Qulity Determintion. Interntionl Symposium co-ordinted y the University of Alsk Se Grnt College Progrm, Anchorge, Alsk, USA, Nov.. Elsevier, Amsterdm, pp Boggio, S.M., Hrdy, W.H., Bitt, J.K., Brnnon, E.L., The influence of dietry lipid source nd lph-tocopheryl cette level on product qulity of rinow trout Ž Slmo girdneri.. Aquculture 51, Bonnet, S., Fuconneu, B., Dvid, K., Fure, A., Lroche, M., Effect of fsting nd stress on post mortem chnges in rown trout rered in se wter. Refrigertion Science nd Technology. Refrigertion nd Aquculture, Bordeux, Frnce, pp Brdford, M.M., A rpid nd sensitive method for the quntittion of microgrm quntities of protein utilising the principle of protein-dye inding. Anl. Biochem. 72, Chen, I.S., Shen, C.S.J., Shepprd, A.J., Comprison of methylene chloride nd chloroform for extrction of fts from food products. J. Am. Oil Chem. Soc. 50, Cho, C.Y., Kushik, S.J., Nutritionl energetics in fish: protein nd energy utiliztion in rinow trout. In: Bourne, G.H. Ž Ed.., Aspects of food production, consumption nd energy vlues. World Rev. Anim. Nutr. 61, Chouert, G., Method for colour ssessment of cnthxnthin pigmented rinow trout ŽSlmo girdneri Rich... Sci. Aliment. 2, Chouert, G., Effects of strvtion nd feeding on cnthxnthin depletion in the muscle of rinow trout Ž Slmo girdneri Rich... Aquculture 46,

20 344 C. Regost et l.raquculture Chouert, G., de l Noue, J., Blnc, J.M., Apprent digestiility of cnthxnthin in rinow trout: effect of dietry ft level, ntiiotics nd numer of pyloric cec. Aquculture 99, Corrze, G., Kushik, S.J., Les lipides des poissons mrins et d eu douce. Ol., Corps Grs, Lipides 6, Dis, J., Alvrez, M.J., Diez, A., Arzel, J., Corrze, G., Butist, J.M., Kushik, S.J., Regultion of heptic lipogenesis y dietry proteinrenergy in juvenile Europen sess Ž Dicentrrchus lrx.. Aquculture 161, Dis, J., Corrze, G., Arzel, J., Alvrez, M.J., Butist, J.M., Lopez-Bote, C., Kushik, S.J., Effets du rpport proteinerenergie des regimes limentires chez l truite et le r d elevge. Perspectives de controle ˆ nutritionnel. Cyium 23, , suppl. 1. Dunjski, E., Texture of fish muscle. J. Texture Stud. 10, Einen, O., Roem, A.J., Dietry proteinrenergy rtios for Atlntic slmon in reltion to fish size: growth; feed utilistion nd slughter qulity. Aqucult. Nutr. 3, Einen, O., Skrede, G., Qulity chrcteristics in rw nd smoked fillets of Atlntic slmon ŽSlmo slr., fed high-energy diets. Aqucult. Nutr. 4, Einen, O., Thomssen, M.S., Strvtion prior to slughter in Atlntic slmon Ž Slmo slr.: II. White muscle composition nd evlution of freshness, texture nd colour chrcteristics in rw nd cooked fillets. Aquculture 169, Einen, O., Wgen, B., Thomssen, M.S., Strvtion prior to slughter in Atlntic slmon ŽSlmo slr.: I. Effects on weight loss, ody shpe, slughter nd fillet-yield, proximte nd ftty cid composition. Aquculture 166, Fuconneu, B., Chmitilly, J., Andre, S., Crdinl, M., Cornet, J., Vllet, J.L., Dumont, J.P., Lroche, M., Crcteristiques de l chir de truite rc en ciel: II. Composntes physiques et sensorielles. Sci. Aliment. 13, Folch, J., Lees, M., Stnley, G.H.S., A simple method for the isoltion nd purifiction of totl lipids from niml tissues. J. Biol. Chem. 226, Fremont, L., Leger, C., Le trnsport des lipides plsmtiques. In: Fontine, M. Ž Ed.., Nutrition des Poissons. Editions du Centre Ntionl de l Recherche Scientifique, Pris, pp Gudn, J., Metiller, R., Guillume, J., Nutrition compree de l truite rc en ciel ŽOncorhynchus mykiss., l truite frio Ž Slmo trutt. et le sumon coho Ž Oncorhynchus kisutch.. Effet des tux de proteines totles et de lipides. ICES 5, Gjedrem, T., Flesh qulity improvement in fish through reeding. Aqucult. Int. 5, Greene, D.H.S., Selivonchick, D.P., Effects of dietry vegetle, niml nd mrine lipids on muscle lipid nd hemtology of rinow trout Ž Oncorhynchus mykiss.. Aquculture 89, Heming, T.A., Pleczny, E.D., Compositionl chnges in skin mucus nd lood serum during strvtion of trout. Aquculture 66, Hemre, G.I., Sndnes, K., Effect of dietry lipid level on muscle composition in Atlntic slmon Slmo slr. Aqucult. Nutr. 5, Hillestd, M., Johnsen, F., High-energyrlow protein diets for Atlntic slmon: effects on growth, nutrient retention nd slughter qulity. Aquculture 124, Hillestd, M., Johnsen, F., Austreng, E., Asgrd, T., Long-term effects of dietry ft level nd feeding rte on growth, feed utilistion nd crcss qulity of Atlntic slmon. Aqucult. Nutr. 4, Hsu, R.Y., Butterworth, P.H.W., Porter, J.W., Pigeon liver ftty cid synthetse. In: Lowenstein, J.M. Ž Ed.., Methods in Enzymology Acdemic Press, New York, vol. 14, pp Iritni, N., Iked, Y., Fukud, H., Ktsurd, A., Comprtive study of lipogenic enzymes in severl vertertes. Lipids 19, ITCF, STAT-ITCF, 4 eme ` ed. Service des Etudes Sttistiques, Pris. Jeziersk, B., Hzel, J.R., Gerking, S.D., Lipid moiliztion during strvtion in the rinow trout, Slmo girdneri Richrdson, with ttention to ftty cids. J. Fish Biol. 21, Johnsson, L., Kiessling, A., Effects of strvtion on rinow trout. Act Agric. Scnd. 41, Kushik, S.J., Cuzon, G., Besoins nutritionnels, formules types, tles de rtionnement, et donnees diverses. In: Guillume, J., Kushik, S., Bergot, P., Metiller, R. Ž Eds.., Nutrition et Alimenttion des Poissons et Crustces. INRA Editions, Pris, Frnce, pp

21 C. Regost et l.raquculture Kushik, S.J., Luquet, P., Endogenous nitrogen loss from the muscle of rinow trout strved in freshwter nd in sewter. Ann. Hydroiol. 8, Kushik, S.J., Medle, F., Energy requirements, utiliztion nd dietry supply to slmonids. Aquculture 124, Kushik, S.J., Crvedi, J.P., Llles, J.P., Sumpter, J., Fuconneu, B., Lroche, M., Prtil or totl replcement of fish mel y soy protein on growth, protein utiliztion, potentil estrogenic or ntigenic effects, cholesterolemi nd flesh qulity in rinow trout. Aquculture 133, Kuniski, N., Tkd, K., Mtsuur, H., On the study of lipids contents, muscle hrdness nd ftty cid compositions of wild nd cultured horse mckerel. Fish. Sci. 52, Lroche, M., Bonnet, S., Fuconneu, B., Mrcel, J., Evolution post mortem de quelques crcteris- tiques de l chir de truite frio Ž Slmo trutt. et de crpe Ž Cyprinus crpio.. Refrigertion Science nd Technology. Refrigertion nd Aquculture, Bordeux, Frnce, pp Lroche, M., Fuconneu, B., Mrcel, J., Effet de l duree et des conditions de stockge Žrefrigertion et congeltion. sur des crcteristiques de texture de filets de truite frio Ž Slmo trutt. et de crpe Ž Cyprinus crpio.. Refrigertion Science nd Technology. Refrigertion nd Aquculture, Bordeux, Frnce, pp Lee, D.J., Putnm, G.B., The response of rinow trout to vrying proteinrenergy rtios in test diet. J. Nutr. 103, Lie, Ø., Huse, I., The effect of strvtion on the composition of Atlntic slmon Ž Slmo slr.. Fisk. Dir. Skr., Ser. Ernoering 5, Likimni, T.A., Wilson, R.P., Effects of diet on lipogenic enzyme ctivities in chnnel ctfish heptic nd dipose tissue. J. Nutr. 112, Lin, H., Romsos, D.R., Tck, P.I., Leveille, G.A., Influence of dietry lipid on lipogenic enzyme ctivities in coho slmon Ž Oncorhynchus kisutch.. J. Nutr. 107, Lin, H., Romsos, D.R., Tck, P.I., Leveille, G.A., Effects of fsting nd feeding vrious diets on heptic lipogenic enzyme ctivities in coho slmon Ž Oncorhynchus kisutch.. J. Nutr. 107, Nickell, D.C., Bromge, N.R., The effect of dietry lipid level on vrition of flesh pigmenttion in rinow trout Ž Oncorhynchus mykiss.. Aquculture 161, Srgent, J., Henderson, R.J., Tocher, D.R., The lipids. In: Hlver, J.E. Ž Ed.., Fish Nutrition. Acdemic Press, Sn Diego, pp Sheehn, E.M., O Connor, T.P., Sheehy, P.J.A., Buckley, D.J., FitzGerld, R., Effect of dietry ft intke on the qulity of rw nd smoked slmon. Irish J. Agric. Food Res. 35, Sigurgisldottir, S., Torrissen, O., Lie, Ø., Thomssen, M., Hfsteinsson, H., Slmon qulity: methods to determine the qulity prmeters. Rev. Fish. Sci. 5, Stone, H., Sidel, J.L., Oliver, S., Woolsey, A., Singleton, R.C., Sensory evlution y quntittive descriptive nlysis. Food Technol. 28, Storekken, T., Austreng, E., Rtion levels for slmonids: II. Growth, feed intke, protein digestiility, ody composition, nd feed conversion in rinow trout weighing kg. Aquculture 60, Storekken, T., Hung, S.S.O., Clvert, C.C., Plisetsky, E.M., Nutrient prtitioning in rinow trout t different feeding rtes. Aquculture 96, Szczesnick, A.S., Humugh, P.R., Block, H.W., Behviour of different foods in the stndrd sher compression cell of the sher press nd the effect of smple weight on pek re nd mximum force. J. Texture Stud. 1, Tkeuchi, T., Wtne, T., The effects of strvtion nd environmentl temperture on proximte nd ftty cid composition of crp nd rinow trout. Bull. Jpn. Soc. Sci. Fish. 48, Thomssen, M.S., Røsjø, C., Different fts in feed for slmon: influence on sensory prmeters, growth rte nd ftty cids in muscle nd hert. Aquculture 79, Torissen, O.J., Pigmenttion of slmonids: fctors ffecting crotenoid deposition in rinow trout Ž Slmo girdneri.. Aquculture 46, Vergr, J.M., Roin, L., Izquierdo, M., de l Higuer, M., Protein spring effect of lipids in diets for fingerlings of gilthed se rem. Fish. Sci. 62,