Stale Refstie a, Trond Storebakken a,), Andries J. Roem b,1. Abstract

Transcription

1 Aquulture Feed onsumption nd onversion in Atlnti slmon ž Slmo slr / fed diets with fish mel, extrted soyen mel or soyen mel with redued ontent of oligoshrides, trypsin inhiitors, letins nd soy ntigens Stle Refstie, Trond Storekken,), Andries J. Roem,1 AKVAFORSK Institute of Aquulture Reserh AS, P A.O. Box 203, Sunndlsør N-6600, Norwy Nutreo Aquulture Reserh Centre, StÕnger N-4000, Norwy Aepted 5 Jnury 1998 Astrt The ojetives of the experiment were to exmine pltility of diets ontining two different soyen mels in Atlnti slmon Ž Slmo slr. previously fed fish mel diets, nd to seprte effets of feed intke nd physiologil ftors in soyen mel on growth nd feed onversion. A fish mel-sed ontrol diet Ž FM. nd two diets with 40% of the protein from either tosted, extrted soyen mel Ž SBM., or soyen mel with redued ontent of oligoshrides nd ntinutritionl ftors Ž RO-SBM. were fed to 107-g slmon in sewter for 55 dys. The fish were weighed t dys 28 nd 55, nd feed onsumption ws monitored dily. The FM diet ontined 100 mg kg of the inert mrker Y2O 3, while the soyen mel diets ontined 100 mg kg of Y2O 3. During dys 25 28, feed preferene nd dpttion test ws rried out. Slmon fed the FM diet were either fed equl mounts of the FM nd SBM diets or the FM nd RO-SBM diets. Fish previously fed the SBM or RO-SBM diets were fed equl mounts of the respetive soyen diet nd the FM diet. At dy 28, preferenes for the different diets were estimted y determining the reltive proportion of Y nd Y in stripped fees. At the end of the experiment, fees were gin stripped to determine digestiility of the diets. Both the SBM nd the RO-SBM diets were ) Corresponding uthor. Tel.: q ; fx: q ; e-mil: trond.storekken@kvforsk.nlh.no. 1 Present ddress: Trouw Nutrition, NL-3880 AE Putten, Netherlnds r98r$19.00 q 1998 Elsevier Siene B.V. All rights reserved. PII S

2 302 S. Refstie et l.raquulture redily epted y S. Slr, s the fish onsumed similr mounts of either of the two diets nd the FM diet in the preferene test. The dily feed onsumption, mesured s perent of ody weight, ws initilly lower in the SBM fed fish, ut ws similr in ll tretments during the lst prt of the experiment. Thus, the fish ppered to dpt to some ftor in the SBM whih did not notly ffet pltility. Growth rte, feed onversion nd digestiilities of nitrogen, ft nd energy were lower in the slmon fed the SBM diet thn the FM nd RO-SBM diets, while they were similr in slmon fed the RO-SBM nd FM diets. When feeding the SBM diet, mjor reson for redued feed onversion nd, therey, growth, ppered to e lowered digestiility of nutrients. q 1998 Elsevier Siene B.V. All rights reserved. Keywords: Feed onsumption; Adpttion; Pltility; Digestiility; Feed onversion; Growth; Soyen mel-oligoshrides; Trypsin inhiitors; Letins; Soy ntigens; Atlnti slmon Slmo slr 1. Introdution Soyens ontin severl ompounds whih my negtively interfere with the digestive proess Ž Rkis, Suh soyen omponents re onsidered to e the mjor ftors responsile for the negtive effet on growth seen in Atlnti slmon Ž Slmo slr. when repling high dietry levels of fish mel with soyen mel ŽOlli et l., 1994, However, when slmon re dpted to fish mel-sed diets, swithing to diets with high inlusion levels of soy protein my redue feed onsumption nd growth temporrily Ž Storekken et l., Even moderte redutions in feed onsumption my severely ffet growth in slmon in given period ŽEinen et l., Thus, the negtive effet on growth seen in slmon when repling high levels of fish mel in the diet y soyen mel my potentilly e prtitioned into temporry response used y pltility nd more permnent response used y other ftors. Suh temporry response nd need for dpttion hs previously een demonstrted in rinow trout y Refstie et l. Ž Trout tht were dpted to fish mel diet hd ler preferene for this diet, nd onsumed only smll proportion of diet with 40% of the protein oming from tosted, extrted soyen mel. When the fish hd een fed the soyen diet for 7 dys, they onsumed 59% of the fish mel diet nd 41% of the soyen diet. This indited tht the replement of fish mel y soyen mel hnged the omposition of flvour omponents nd feeding ttrtnts in the diets. Still, the dpttion to the soyen diet ws rpid. In the present experiment, tosted, extrted soyen mel Ž SBM. or soyen mel with redued ontent of oligoshrides nd ntinutritionl ftors Ž RO-SBM. ws inluded in slmon diets t levels orresponding to 40% soyen protein of totl protein. The ims of the experiment were: Ž. 1 to determine if feed onsumption in Atlnti slmon previously fed fish mel-sed diets ws ffeted when fed soyen mel ontining diets; if so, Ž. 2 to find out whether this ws used y relutne to onsume the soyen mel diets, nd whether slmon would dpt to soyen mel diets with time; Ž. 3 to seprte effets of diet eptility nd physiologil ftors in soyen mels ffeting the digestiility, growth nd feed onversion; nd Ž. 4 to ompre SBM nd RO-SBM s fish mel replers in slmon diets.

3 2. Mterils nd methods 2.1. Soyen mels S. Refstie et l.raquulture A tosted, extrted soyen mel ws mnuftured from hulled nd flked soyens Ž SBM, Denosoy, Denof, Fredrikstd, Norwy.. The soyen mel with redued ontent of oligoshrides nd ntinutritionl ftors ŽRO-SBM, HP-300, Hmlet Protein, Horsens, Denmrk. ws mde from deftted soyens whih were treted y proprietry proess. Aording to the speifitions of the produer, this proess elimintes the soyen oligoshrides, nd redues the levels of soy trypsin inhiitors, letins nd ntigens. This results in higher protein onentrtion in the produt thn in regulr soyen mel nd imprts hrteristi flvour. The soyen mels Ž Tle 1. were nlysed for proximte omposition Ždry mtter, nitrogen, rude ft nd sh. y Nutreo ARC lortory, s desried y Einen nd Roem Ž In vitro digestiility of protein Žinuted in shker t 140 rpm nd 428C, with N HCl or 2 mg l pepsin nd N HCl for 16 h, filtered, Kjeldhl-N determined in filter pper with smple; results given s g digestile protein relted to id-insolule protein. nd wter-solule protein Žoiled in distilled wter for 30 min, filtered, Kjeldhl-N determined in the extrt., were lso nlysed y Nutreo Tle 1 Composition of the soyen mels Soyen mel SBM RO-SBM Chemil omposition Dry mtter DM, g kg ( y 1) In DM kg Protein, g Ft, g Ash, g Dietry fire, g Protein qulity Õriles Solule nitrogen, g kg In vitro digestile protein, g kg In 100 g protein Sulfhydryl groups, mmol Disulphide onds, mmol Antinutritionl ftors Letins, mg g d TIA, mg g Tosted, extrted soyen mel Ž Denosoy, Denof, Fredrikstd, Norwy.. Soyen mel with redued ontent of oligoshrides nd ntinutritionl ftors ŽHP-300, Hmlet Protein, Horsens, Denmrk.. N =6.25. d Trypsin inhiitor tivity.

4 304 S. Refstie et l.raquulture ARC lortory. Trypsin inhiitor tivity Ž TIA, Hmmerstrnd et l., ws nlysed y AKVAFORSK. Letins Ž Vretld, were nlysed y Msterl Ž Putten, Hollnd.. Sulfhydryl Ž SH. groups nd disulphide Ž S S. onds ŽOpstvedt et l., were nlysed y the Norwegin Herring Oil nd Mel Reserh Institute Ž Bergen, Norwy.. Dietry fire ws nlysed y Sttkorn Ž Oslo, Norwy., ording to AACC Ž method No Diets Three diets fish mel-sed ontrol diet Ž FM. nd two diets with 40% of the rude protein supplied y either SBM or RO-SBM were mnuftured y T. Skretting Ž Stvnger, Norwy., using extrusion tehnology Ž Tle 2.. The prtile size ws 4 mm. Tle 2 Formultion, nd omposition of the diets Diet ode FM SBM RO-SBM Formultion, g kg y 1 Fish mel SBM RO-SBM Whet Fish oil d DL-methionine CŽ H PO Yttrium oxide Ž Y O Ytterium oxide Ž Y O e Constnt ingredients Chemil omposition Dry mtter DM, g kg ( y 1) f In DM kg Protein, g Ft, g Ash, g Strh, g Dietry fire, g Gross energy, MJ Norse LT-94 Ž Norsildmel, Bergen, Norwy.., See Tle 1. d DL-methionine Ž Deguss, Hnu, Germny.. e Constnt ingredients, g kg : 30 g Digestile inder Žproprietry omposition, T. Skretting, Stvnger,. Ž Ž Norwy ; 20 g Vitmin nd minerl premix vlues speified y T. Skretting, Stvnger, Norwy kg.: Vitmin A, 4000 IU; vitmin D 3, 1500 IU; -toopherol, 0.15 g; thimin, 0.01 g; rioflvin, g; pyridoxine, 0.01 g; pnthotente, g, niin, 0.06 g; folte, 3.0 mg; vitmin B 12, 0.02 mg; iotin, 0.15 mg; vitmin K 3, 0.05 g; holine, 5.5 mg; inositol, 0.08 g; Mn, 18.4 mg; Zn, 78 mg.; 0.4 g Rovimix sty-c, sorte polyphosphte Ž Hoffmnn-L Rohe, Bsle, Switzerlnd.; 0.3 g Crophyll Pink, 8% stxnthin formultion Ž Hoffmnn-L Rohe, Bsle, Switzerlnd.. f N =6.25.

5 S. Refstie et l.raquulture The diets were formulted to ontin the sme lulted mounts of ville phosphorus nd sulphur-ontining mino ids Ž ysteineq methionine., nd to e isonitrogenous nd isoenergeti on rude protein nd gross energy sis. The pity of the diets to sor ft differed, however, nd the FM diet ontined more protein nd less ft thn the soyen mel diets. The SBM diet ontined slightly less protein nd more ft thn the RO-SBM diet. The FM diet nd the two diets with soyen mel were supplemented with different inert mrkers to filitte mesurements of qulittive preferene. The FM diet on tined 100 mg kg of Y O Ž Y. 2 3, while the two soyen mel diets ontined 100 mg kg of Y O Ž Y., oth otined from Sigm Ž St. Louis, MO, USA Dry mtter, nitrogen, rude ft, sh nd dietry fire were nlysed s desried for the soyen mels. Strh Ž Englyst et l., ws nlysed y Msterl. Gross energy Ž Prr 1271 Oxygen Bom Clorimeter, Prr, Moline, IL, USA. ws mesured y AKVAFORSK. Totl yttrium oxide nd ytterium oxide ws nlysed s desried y Refstie et l. Ž Filities, fish nd smpling The experiment ws rried out t Nutreo ARC s Lerng Reserh Sttion in Jørpelnd, Norwy. The experiment ws onduted over two periods of 28 nd 27 dys. The FM diet ws fed to six groups of fish during the first period, nd to three groups of fish during the seond period. The diets with SBM or RO-SBM were fed to three groups of fish eh throughout the experiment. Prior to the experiment, Atlnti slmon were fed ommeril fish mel-sed diets Ž T. Skretting.. Two weeks prior to the strt of the experiment, 12 groups Ž 50 fishrgroup. Ž 3 were rndomly distriuted to fire glss tnks 1=1=0.6 m, wter depth m. supplied with sewter 7 88C. The slinity of the wter ws pproximtely 33 g l. Eh tnk ws equipped with semi-losed lid, sumerged light Ž ontinuous light. nd mesh-wire feed-wste olletor in the outlet. Feed wste ws determined sed on reovery tests Hellnd et l., The wter flow ws 10 l min, nd the O2 ontent of outlet wter ws never elow 9 mg l. The fish were fed ontinuously, using eletrilly driven dis feeders Ž Akvprodukter, Sunndlsør, Norwy.. The initil men weight of the fish ws 107.3"1.1 g Ž men"s.e.m... The fish were weighed in ulk t the strt of the experiment nd t dy 28. Individul weights nd fork lengths were mesured t dy 55. During dys 1 25 nd 29 55, feeding ws pproximtely 20% in exess, sed on feed wste. During the preferene nd dpttion test Ž dys , three of the groups fed the FM diet nd the groups fed the SBM diet were offered mixture with equl mounts of the two diets. Simultneously, the three remining groups of fish fed the FM diet nd the groups fed the RO-SBM diet were offered equl mounts of these diets. The slmon were fed 100% in exess, ensuring tht the fish ould feed exlusively on the diet they preferred. At dy 28, fees were stripped s desried y Austreng Ž 1978., nd pooled y tnk. The durtion of the test period ws sed on riteri previously reviewed y Refstie et l. Ž 1997., to ensure representtive smples of fees.

6 306 S. Refstie et l.raquulture When the preferene test ws ompleted, three of the groups dpted to the FM diet were terminted, nd the three diets were fed to the originl triplite groups of fish for nother 27 dys. At dy 55, the fish were deprived of feed for 2 4 h. Fees were then stripped from the fish for digestiility determintion prior to weighing. The fees were pooled y tnk. Chemil omposition of fees ws determined s desried for the diets, omitting the nlyses of strh nd dietry fire Clultions nd sttistil nlyses Condition ftor ws lulted s: 100 = W Ž 3. i= L i, where Wi is individul weight, nd L is individul fork length. Speifi growth rte Ž SGR. i ws lulted s: w x SGR s 100 = lnw1 y lnw 0 = D, where W0 nd W1 represent initil nd finl weights Ž tnk mens., respetively, nd D represents the numer of feeding dys. Feed onversion rtio FCR ws lulted s F = G, where F is onsumption of dry mtter from feed nd G is the weight gin. Instntneous dily feed intke ws lulted s: 100=F d=wd, where Fdsfeed intke t dy d, nd Wdsweight t dy d extrpolted ording to Iwm nd Tutz Ž 1981., modified y Cho Ž 1992., Ž 1r3 using the therml-unit growth oeffiient TGC. TGC ws lulted s: TGCs W 1 1r3 yw. = Ž ÝD8., where ÝD8 is the therml sum Ž 0 feeding dys=verge temperture, 8C.. Nutrient digestiilities of the four experimentl diets were determined y the indiret method, s desried y Austreng Ž 1978., using Y O nd Y O s inert mrkers Tle 3 Growth, feed intke, feed onversion nd survivl Ž men"s.e.m., ns3. Diet FM SBM RO-SBM Weight, g 0 dys 109"1 106"3 108"2 55 dys 239"5 200"12 232"3 ( 3) y 1 Condition ftor, g m 55 dys 1.11" " "0.01 SGR 0 28 dys 1.69" " " dys 1.16" " "0.03 Feed intke, perent of initil weight 0 28 dys 40.3"0.8 d 33.7" " dys 34.1" " "0.9 FCR, g feed intker g ody weight inrese 0 28 dys 0.66" " " dys 0.92" " "0.01 SurÕiÕl, % ( umultiõe) 0 55 dys 99.3" " "0.0, Different supersript letters denote signifint differenes within row Ž P ,d Different supersript letters denote trends within row Ž P

7 S. Refstie et l.raquulture insted of Cr2O 3. Qulittive preferene ws estimted s the proportion of Y nd Y in fees, s previously desried Ž Refstie et l., The results were nlysed y the Generl Liner Model proedure ŽSttistil Anlysis Systems Institute, Men results per tnk were sujet to one-wy nlysis of vrine, with diet s the lss vrile. Signifint differenes were rnked y Dunn s multiple rnge test. The level of signifine ws hosen t P-0.05, nd the results re presented s mens" S.E.M. 3. Results During the first 28 dys, the growth ws fster nd the feed onversion ws more effiient in Atlnti slmon fed the fish mel ontrol diet Ž FM. nd the diet with Fig. 1. Instntneous dily feed intke perent of ody weight nd umultive feed intke g. The fish were weighed nd fees were stripped t dy 28.

8 308 S. Refstie et l.raquulture soyen mel with redued ontent of oligoshrides nd ntinutritionl ftors Ž RO-SBM. thn in slmon fed the diet with tosted, extrted soyen mel Ž SBM. Ž Tle 3.. Simultneously, the instntneous dily feed intke Žperent of ody weight, Fig. 1. nd feed intke, mesured s perent of initil ody weight Ž Tle 3., tended to e lower in the groups fed the SBM diet thn in the other groups. Slmon dpted to the FM diet for 25 dys showed no preferene for this diet when given hoie etween the FM diet nd either of the diets with SBM or RO-SBM. Likewise, slmon dpted to the RO-SBM diet did not disriminte etween this diet nd the FM diet. The fish dpted to the SBM diet onsumed slightly less of this diet thn of the FM diet Ž Tle 4.. The feed intke ws temporrily redued fter the initil weighing, nd the stripping of fees nd weighing t dy 28. The feed intke ws, however, norml within 5 dys fter these smplings Ž Fig. 1.. During the lst 27 dys Ž Tle 3., differenes in growth nd feed onversion etween slmon fed the different diets showed pttern similr to tht of the first 28 dys. Within this period, the instntneous dily feed intke nd feed intke, mesured s perent of initil ody weight, did not differ etween ny fish groups. During the totl period of 55 dys, however, the umultive feed intke ws lower in the fish groups fed the SBM diet thn in the other groups Ž Fig. 1.. The umultive survivl ws 100% t 28 dys, nd verged 99% t 55 dys ŽTle 3.. The survivl ws not ffeted y diet. At the end of the experiment, the ondition ftor did not differ etween the slmon fed the FM diet or the SBM diet, while it ws 5.4% higher in the fish groups fed the RO-SBM diet Ž Tle 3.. The digestiility of nitrogen Ž Tle 5. ws signifintly lower in the fish groups fed the SBM diet ompred with the other groups. Similr trends Ž P were lso oserved for the digestiilities of ft nd energy. The ontent of dry mtter in fees ws higher in the fish groups fed the FM diet thn in the groups fed the diets with SBM or Tle 4 Reltive feed intke of FM nd SBM or FM nd RO-SBM diets when the diets were fed in omintions fter 25-dy period of dpttion Ž men"s.e.m., ns3. Diet omintions Diet fed in dpttion period 1 2 Reltive feed intke, % FM SBM RO-SBM FM nd SBM diets FM 52"2 56"1 SBM 48"2 44"1 FM nd RO-SBM diets FM 52"2 48"2 RO-SBM 48"2 52"2, Different supersript letters denote signifint differenes within tretment Ž P The FM diet ontined 100 mg kg of the inert mrker Y2O 3, while the SBM nd RO-SBM diets ontined 100 mg kg of Y2O 3. 2 Determined s the proportion of the inert mrkers in fees.

9 S. Refstie et l.raquulture Tle 5 Digestiility Ž %., fel dry mtter Ž %. nd digestile protein Ž DP, N =6.25. to digestile energy Ž DE. rtio Ž g MJ. with the diets Ž men"s.e.m., ns3. Diet FM SBM RO-SBM Apprent digestiility Nitrogen 84.7" " "0.2 Ft 82.0"1.5 d 74.6" "1.0 Energy 72.5"0.9 d 66.8" "0.9 Fel DM Ž %. 17.2" " "0.1 DP DE rtio 21.9" " "0.2, Different supersript letters denote signifint differenes within row Ž P ,d Different supersript letters denote trends within row Ž P RO-SBM. Between the groups fed the SBM or RO-SBM diets, there ws no differene in the fel dry mtter ontent. The lower ft ontent in the FM diet thn in the soyen mel diets resulted in higher rtio of grm digestile protein Ž DP, N = to MJ digestile energy Ž DE. in the FM diet. Due to the low digestiility of ft in the SBM diet, the DP DE rtios were similr in the SBM nd RO-SBM diets, even though the SBM diet ontined more ft thn the RO-SBM diet Ž Tle Disussion The growth rtes of Atlnti slmon fed the fish mel Ž FM. diet were 10 30% higher thn previous results otined with slmon of similr size nd rised t the sme tempertures Ž Austreng et l., 1987., s were the growth rtes of the slmon fed the diet with 40% of the protein supplied y the soyen mel with redued ontent of oligoshrides nd ntinutritionl ftors Ž RO-SBM.. The growth rte of the slmon fed the diet with 40% of the protein from the tosted, extrted soyen mel Ž SBM. ws similr to the results otined in the previous experiments. A reent experiment with slmon of similr size nd kept t the sme tempertures, Storekken et l. Ž ompred fish mel diet with diets with 75% of the protein from soy protein onentrte. Compred with tht experiment, the fish in the present experiment onsumed more thn twie s muh feed, nd the growth rtes were 20 80% higher. Although low digestiility vlues when ompred with previous experiments with extruded diets Ž Aksnes, 1995; Storekken et l., 1998., this illustrtes the good ondition of the fish, nd the qulity of the diets nd feeding proedure used in the present experiment. Also previously, Atlnti slmon hve een shown to grow slower on diet with 40% of the protein from soyen mel thn on fish mel-sed diet Ž Olli et l., In the present experiment, fish fed the SBM diet onsumed pproximtely 18% less feed nd gined pproximtely 19% less weight thn the other groups during the totl period of 55 dys. However, ll groups of fish hd similr onsumption of feed during the lst Ž 27 dys of the experiment mesured oth s instntneous dily onsumption perent of

10 310 S. Refstie et l.raquulture ody weight. nd s pooled onsumption for the whole period Žperent of initil ody weight.. Furthermore, the growth remined slower nd the feed onversion remined less effiient with the SBM diet during the lst 27 dys of the experiment, lthough the instntneous dily feed intke then ws similr to tht otined with the other diets. Supported y the poorer digestion of the SBM diet thn of the other diets, this strongly indites tht some dietry ftorž. s ws responsile for the poor utilistion nd possily the initilly low instntneous dily onsumption of the SBM diet. Thus, the slower growth with the SBM diet thn with the other diets does not pper to e simple mtter of redued feed onsumption. The preferene nd dpttion test demonstrted only moderte differenes in diet pltility. The only signifint differene ws tht the fish dpted to the SBM diet onsumed 44% of this diet nd 56% of the FM diet. Thus, it ppers likely tht pltility ws not the mjor ftor responsile for the lower initil onsumption of the SBM diet thn of the other diets. It is diffiult to identify whih ftors in the SBM ffeted Atlnti slmon negtively sed on the present experiment. It is unlikely tht the fish were notly ffeted y the het lile soyen trypsin inhiitors nd letins Ž Rkis, The trypsin inhiitor tivity vlues in oth soyen mels were well elow the tolerne limit for rinow trout Ž Krogdhl et l., 1994; Olli nd Krogdhl, nd Atlnti slmon ŽOlli et l., 1994,.. Consequently, the letin vlues in the soyen mels were low, s the destrution of letins prllels the intivtion of trypsin inhiitors when heting soyen mels Ž Rkis, 1974; vn den Ingh et l., Additionlly, oth soyen mels were sujet to seond het tretment during the extrusion of the experimentl diets. Possily, the SBM ontined some het-stle ftorž. s tht distured the digestive proesses, nd eventully ffeted the pity for mximum feed intke. If so, suh ftorž. s ws pprently eliminted in the RO-SBM. The results demonstrte the need to monitor severl ftors tht my ffet the nutrient sorption nd therey the fish growth when evluting feed ingredients in fish feeds. As previously demonstrted y Einen et l. Ž 1995., moderte differenes in feed onsumption nd nutrient sorption umultively severely ffeted the finl weight nd the retention of nutrients in the fish. Furthermore, the experiment demonstrtes tht reful monitoring of dily feed onsumption in omintion with mesurements of diet eptility nd digestiility of nutrients is simple ut useful tool to seprte key ftors ffeting fish growth. For growth in slmon t similr size, Grisdle-Hellnd nd Hellnd Ž did not Ž find suoptiml digestile protein to digestile energy DP DE. rtios in diets within the rnge of g MJ. For lrger slmon 1 5 kg, the optiml dietry DP DE rtio for growth ppers to e within the rnge of g MJ, deresing with inresing fish weight Einen nd Roem, Therefore, onsidering the DP DE rtios in the present experimentl diets, growth rtes of slmon fed different diets were proly not notly ffeted y the differenes in protein nd ft etween the diets. As the RO-SBM diet ws well digested nd prtitioned into growth, the different ft ontents in the experimentl diets my still hve led to higher ft deposition in fish fed the RO-SBM diet thn in fish fed the other diets. This my to some extent explin the slightly higher ondition ftor in these fish thn in fish fed the other diets.

11 S. Refstie et l.raquulture The temporrily redued feed intke fter weighing nd stripping of fees is rtionlised y the hndling stress. Similr effets were oserved y Hjen et l. Ž when repetedly stripping fees. The oserved need for out five dys to normlise the feed intke fter hndling stress is of relevne when plnning future trils with Atlnti slmon. In onlusion, diets with 40% of the fish mel protein repled y protein from SBM or RO-SBM were pltle nd redily epted y Atlnti slmon dpted to fish mel-sed diets. Thus, Atlnti slmon pper to e flexile in their response to hnges in diet formultion. Fish performne ws similr when feeding the fish mel-sed diet nd the RO-SBM diet. When feeding the SBM diet, however, growth nd feed onversion were lower. This ws prtly due to n initilly low feed onsumption, prtly sried to y some other ftor thn diet pltility. The fish needed time to dpt to the SBM diet, ut the dpttion ws not omplete. A mjor ftor ffeting feed onversion nd therey growth when feeding the SBM diet ppered to e het stle ntinutritive omponents in the soyen mel, disturing the sorption of nutrients. These ftors ppered to e sent or detivted in the RO-SBM. Aknowledgements The uthors would like to thnk K. Ingerigtsen, A.L. Lølnd nd G. Brdsen t Nutreo ARC for skillful tehnil ssistne. Finnil support for this experiment ws provided y grnt, Protein Eonomy in Fish Feed y Using Soy, founded y The Norwegin Reserh Counil Ž NTNF grnt No , Trouw Aquulture, T. Skretting nd Denof. Stle Refstie ws supported y grnt No r122, Evlution of Feed Ingredients in Fish, provided y The Norwegin Reserh Counil. Referenes AACC Ž Amerin Assoition of Cerel Chemists., Approved Methods of the Amerin Assoition of Cerel Chemists, 9th edn. AACC, St. Pul, MN, USA. Aksnes, A., Growth, feed effiieny nd slughter qulity of slmon, Slmo slr L., given feeds with different rtios of rohydrte nd protein. Aquult. Nutr. 1, Austreng, E., Digestiility determintion in fish using hromi oxide mrking nd nlysis of ontents from different segments of the gstrointestinl trt. Aquulture 13, Austreng, E., Storekken, T., Asgrd, T., Growth rte estimtes for ultured Atlnti slmon nd rinow trout. Aquulture 60, Cho, C.Y., Feeding systems for rinow trout nd other slmonids with referene to urrent estimtes of energy nd protein requirements. Aquulture 100, Einen, O., Roem, A.J., Dietry proteinrenergy rtios for Atlnti slmon in reltion to fish size: growth, feed utiliztion nd slughter qulity. Aquult. Nutr. 3, Einen, O., Holmefjord, I., Asgrd, T., Tlot, C., Auditing nutrient dishrges from fish frms: theoretil nd prtil onsidertions. Aquult. Res. 26, Englyst, H.N., Kingmn, S.M., Cummings, J.H., Clssifition nd mesurement of nutritionlly importnt strh frtions. Eur. J. Clin. Nutr. 46, s33 s50. Grisdle-Hellnd, B., Hellnd, S.J., Methods to ssess optiml nutrient omposition of diets for Atlnti slmon. J. Appl. Ihthyol. 11,

12 312 S. Refstie et l.raquulture Hjen, W.E., Bems, R.M., Higgs, D.A., Dosnjh, B.S., Digestiility of vrious feedstuffs y post-juvenile hinook slmon Ž Onorhynhus tshwytsh. in se wter: 1. Vlidtion of tehnique. Aquulture 112, Hmmerstrnd, G.E., Blk, L.T., Glover, J.D., Trypsin inhiitors in soy produts: modifition of the stndrd nlytil proedure. Cerel Chem. 58, Hellnd, S.J., Grisdle-Hellnd, B., Nerlnd, S., A simple method for the mesurement of dily feed intke of groups of fish in tnks. Aquulture 139, Iwm, G.K., Tutz, A.F., A simple growth model for slmonids in htheries. Cn. J. Fish. Aqut. Si. 38, Krogdhl, A., Le, T.B., Olli, J.J., Soyen proteinse inhiitors ffet intestinl trypsin tivities nd mino id digestiilities in rinow trout Ž Onorhynhus mykiss.. Comp. Biohem. Physiol. A 107, Olli, J.J., Krogdhl, A., Nutritive vlue of four soyen produts s protein soures in diets for rinow trout Ž Onorhynhus mykiss, Wlum. rered in fresh wter. At Agri. Snd. A 44, Olli, J.J., Krogdhl, A., vn den Ingh, T.S.G.A.M., Brtts, L.E., Nutritive vlue of four soyen produts in diets for Atlnti slmon Ž Slmo slr L... At Agri. Snd. A 44, Olli, J.J., Hjelmelnd, K., Krogdhl, A., Soyen trypsin inhiitors in diets for Atlnti slmon ŽSlmo slr, L..: effets on nutrient digestiilities nd trypsin in pylori e homogente nd intestinl ontent. Comp. Biohem. Physiol. A 109, Olli, J.J., Krogdhl, A., Venø, A., Dehulled solvent-extrted soyen mel s protein soure in diets for Atlnti slmon, Slmo slr L. Aquult. Res. 26, Opstvedt, J., Miller, R., Hrdy, R.W., Spinelli, J., Het indued hnges in sulfhydryl groups nd disulfide onds in fish protein nd their effet on protein nd mino id digestiility in rinow trout Ž Slmo girdneri.. J. Agri. Food Chem. 32, Rkis, J.J., Biologil nd physiologil ftors in soyens. J. Am. Oil Chem. So. 51, 161A 174A. Refstie, S., Hellnd, S.V., Storekken, T., Adpttion to soyen mel in diets for rinow trout, Onorhynhus mykiss. Aquulture 153, Sttistil Anlysis Systems Institute, SASrSTAT w Guide for Personl Computers, Version 6. SAS Institute, Cry, NC, USA, 378 pp. Storekken, T., Sherer, K.D., Roem, A.J., Avilility of protein, phosphorus nd other elements in fish mel, soy protein onentrte nd phytse treted soy protein onentrte sed diets to Atlnti slmon, Slmo slr. Aquulture, 161. vn den Ingh, T.S.G.A.M., Olli, J.J., Krogdhl, A., Alohol-solule omponents in soyens use morphologil hnges in the distl intestine of Atlnti slmon, Slmo slr L. J. Fish Dis. 19, Vretld, P., Purifition of letins y iospeifi ffinity hromtogrphy. Biohem. Biophys. At 434,