Digestibility of extruded peas, extruded lupin, and rapeseed meal in rainbow trout žoncorhynchus mykiss/ and turbot ž Psetta maxima/

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1 Ž. Aquculture Digestiility of extruded pes, extruded lupin, nd rpeseed mel in rinow trout žoncorhynchus mykiss/ nd turot ž Psett mxim/ Christine Burel, Thierry Boujrd, Frncesc Tulli, Sdsivm J. Kushik,) Lortoire de Nutrition des Poissons, Unite mixte INRA-IFREMER, Sttion d Hydroiologie, BP 3, Sint Pee-sur-NiÕelle, Frnce Diprtimento di Scienze dell Produzione Animle, UniÕ. di Udine, Õi S. Muro, 2 I Pgncco ( UD ), Itly Received 22 July 1999; received in revised form 18 Jnury 2000; ccepted 19 Jnury 2000 Astrct Apprent digestiility coefficients Ž ADC. of nutrients nd energy of extruded pes, extruded lupin nd rpeseed mels were determined in juvenile rinow trout nd turot. Extruded lupin ws found to e promising sustitute for fish mel in the diets of trout nd turot, with n cceptle digestiility of its dry mtter Ž 70% in trout nd 81% in turot. nd high digestiility of its protein Ž 96% in trout nd 98% in turot. nd its energy Ž 77% in trout nd 85% in turot.. Extruded pes hd lower digestiility of its protein in trout Ž 88%. thn in turot Ž 92%., nd the ADC of energy, minly supplied s strch, ws reltively low Ž 69% in trout nd 78% in turot.. The digestiility of rpeseed mel ws improved y therml tretment. Without therml tretment, rpeseed mel hd low digestiility of its dry mtter Ž 57%. nd energy Ž 69%. in turot. The vilility of phosphorus ws higher for extruded lupin Ž62% in trout nd 100% in turot. compred to the other plnt-ingredients. When compred to solvent-extrcted mel, the vilility of phosphorus from rpeseed mel ws improved y het tretment in oth species Ž 42% vs. 26% in trout nd 65% vs. 49% in turot.. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Nutrition; Digestiility; Oncorhynchus mykiss; Psett mxim; Pes; Lupin; Rpeseed; Phosphorus ) Corresponding uthor. Tel.: q ; fx: q Ž. E-mil ddress: kushik@st-pee.inr.fr S.J. Kushik r00r$ - see front mtter q 2000 Elsevier Science B.V. All rights reserved. Ž. PII: S

2 286 ( ) C. Burel et l.raquculture Introduction Prtil or even totl replcement of dietry fish mel with soyens Žmel, extruded product or protein concentrte. hs een successfully ccomplished in numer of teleost fishes Ž Tcon, 1994; Kushik et l., 1995; Mmrini et l., Given tht plnt ingredients in generl hve phosphorus contents lower thn tht of fish mels, the incorportion of soyen products in fish feeds is known to reduce phosphorus lods in the effluent wter Ž Bergheim nd Sveir, 1995; Cin nd Grling, However, since Europen production of soyen is extremely limited, it is considered worth exploring the possiilities of using other ingredients Ž pulses, cerels or oil seeds. s fish mel sustitutes. While the content of protein of pes is low Ž -25% dry mtter, DM., it is rich in strch Ž ) 50% DM., with reltively high energy content. In species such s slmonids, the digestive utilistion of polyscchrides or polyholosides is limited ŽSingh nd Nose, 1967; Plmer nd Rymn, 1972., ut het tretments, such s extrusion, re known to rek the structure of strch, nd thus, gretly improve its digestiility ŽBergot, 1979; Bergot nd Breque, ` 1983; Hilton et l., 1981; Kushik Extruded pes hve een successfully used s fish feed ingredient ŽGomes nd Kushik, 1989; Gomes et l., 1993; Gouvei et l., Dehulling leds to decrese in the fire content of pe seeds to improve their digestiility. Thnks to genetic selection, current pe vrieties contin no tnnins ut only low levels of trypsin inhiitors nd lectins ŽBond nd Duc, 1993., which cn e further dectivted with the high tempertures occurring in the extrusion process Ž Melcion nd vn der Poel, Mny improvements hve een mde in the processing conditions of extrusion, preventing excessive heting nd Millrd rection, which oth decreses protein digestiility. Severl works hve lso demonstrted the interest of the incorportion of lupin seed mels, especilly dehulled nd extruded lupin, in the diets for rinow trout ŽDe l Higuer et l., 1988; Gomes nd Kushik, 1989; Hughes, 1988; Moyno et l., 1992; Bngoul et l., 1993; Gouvei et l., Lupin seeds hve high content of protein Ž 35 50% DM. nd re reltively rich in oil Ž out 10%., nd strins of white lupin Ž Lupinus lus. with low lkloid contents re now ville Ž Roemer, But lupin lso contin high proportions of -glctosides Ž 7 15% DM. nd fire Ž 25 30% DM. Ž Ferrndo nd Blum, 1989., reducing the digestiility of its dry mtter. Dehulling indeed decreses the fire content Ž Melcion nd vn der Poel, 1993., wheres it hs no effect on -glctosides, minly loclised in cotyledons. But extrusion tretment increses the utilistion of the components of lupin Ž Bngoul et l., 1993., nd especilly, of the nitrogen-free extrcts. Rpeseed is minly n oil-source Ž 40 45% DM., ut the rpeseed mel otined fter extrction of oil is n interesting protein-source with protein content vrying etween 32% nd 45% DM. In Europe, it is Brssic npus oleifer tht is minly cultivted. Rpeseed mel hs een the oject of numerous studies in rinow trout s potentil sustitute to fish mel ŽYurkowski et l., 1978; Hilton nd Slinger, 1986; Gomes nd Kushik, 1989; Gomes et l., 1993; Adou Dde et l., 1990; McCurdy nd Mrch, While the dvntge of rpeseed mel is the qulity of its protein Žits mino cid profile is more interesting thn tht of soyen., it contins high proportion of fire

3 ( ) C. Burel et l.raquculture Ž 30 40%. esides other nti-nutritionl fctors Ž ANF. such s tnnins, sinpin nd phytic cid. Rpeseeds re lso known to contin glucosinoltes Ž GLS., whose metolites hve goitrogenic ctivity in ll nimls, including fish ŽYurkowski et l., 1978; Higgs et l., 1982, Hrdy nd Sullivn 1983; Letherlnd et l., 1987; Hossin nd Juncey, 1988; Teskeredzic et l., However, the qulity of rpeseed mel hs een considerly improved over the recent pst with genetic selection of new vrieties clled colz 00 with no erucic cid nd with low GLS contents Ž mmolrg DM.. Besides, technologicl tretments, such s dehulling nd the utilistion of high tempertures nd orgnic solvents during oil extrction, llow the decrese of the content of GLS, fire, sinpin nd tnnins Ž Mwson et l., 1995; Higgs et l., The eneficil effects of dry extrusion for reducing the ANF content hs lso een shown Ž Fenwick et l., 1986; Smithrd nd Eyre, 1986., ut such tretment is not yet currently pplied on regulr sis. The present study ws undertken to determine the digestiility of nutrients nd energy of extruded pes, extruded nd dehulled lupin, dehulled nd solvent-extrcted rpeseed mel nd dehulled nd het-treted rpeseed mel Ž pressure-cooking. in freshwter-grown rinow trout nd sewter-grown turot. The pe seeds used were not dehulled in order to estlish if this tretment might e shunted for decresing the cost of the technicl tretment. The potentil of solvent-extrction of rpeseeds, without het tretment, ws lso tested for the colz 00 owing to its economic dvntge in comprison to tht of the pressure-cooking currently used for common rpeseed mels. 2. Mteril nd methods 2.1. Chrcteristics of plnt-protein sources tested Pe Ž Pisum stiõum. nd lupin Ž L. lus. seeds were provided y Union Ntionle Interprofessionelle des Plntes Riches en Proteines Ž UNIP., Pris, Frnce, nd processed y Centre Technique Interprofessionel des Olegineux Metropolitins Ž CETIOM., Bordeux, Frnce. After crushing Žroller grinder; first stge dimeter: 1.9 mm, second stge dimeter: 1.2 mm., the rough flour otined from pes ws directly extruded ŽFrnce extrusion; two long single-screw elements nd two twin-screw elements; men power: 27 kw; inlet moisture: 17%; tempertures: 1868C, 1508C nd 1028C, for sleeves 1, 2 nd 3, respectively; pressure: 26 r; outlet rte: 158 kgrh; speed: 527 rpm; specific mechnicl energy: 114 W hrkg.. Crushed lupin seeds were dehulled y exhustion Ž clener-seprting system Denis D50. efore eing extruded Žmen power: 18 kw; inlet moisture: 17%; tempertures: 1288C, 1068C nd 928C, for sleeves 1, 2 nd 3, respectively; pressure: 38 r; output rte: 101 kgrh; speed: 591 rpm; specific mechnicl energy: 90 W hrkg.. Rpeseeds Ž B. npus., provided y CETIOM, were sumitted to very extensive dehulling tretment Žseeds were lown towrds trget y propeller disk, then the hulls were seprted from the kernels y ir clssifiction nd exhustion using sorter with lowing ottom, nd finlly, kernels were sorted y exhustion using sieve on clener-seprting system Ž Denis D50., in order to reduce their fire content.. Then, two

4 288 ( ) C. Burel et l.raquculture different methods of ft extrction were used. The first method consisted of direct oil extrction without het tretment. Kernels were sumitted to doule-pressing under rollers, then the oil ws extrcted in shking filter Ž Guedu type ML 750. y eight consecutive hexne wshings in percoltion Žprtil filling of the filter with hexne, rewing during 15 min, then filtrtion over nitrogen pressure; temperture C.. The desolventtion ws relised y stem injection Ž3 r, 5 min; mximl temperture: 808C; totl durtion: 2 h.. The second method for extrcting oil, following doulepressing of the kernels, consisted of pressure-cooking Žmen temperture: 978C; pressure: 50 r; output rte: 250 kgrh; men durtion: 1.5 h. with wter injection Žfrom 15 to 30 lrh. using modern system of mechnicl cooking nd power press. The residul oil ws extrcted y six consecutive hexne wshings in percoltion Žtemper- ture C., followed y desolventtion y stem injection Ž5 min; 6 r; mximl temperture: 1058C; totl durtion: 74 min.. Susequent grinding produced the two rpeseed mels: solvent-extrcted rpeseed mel nd het-treted rpeseed mel. All ingredients were ground Ž F 400 mm. efore incorportion into the diets. The chemicl compositions of the ingredients tested re shown in Tle Digestiility mesurements Ž. The pprent digestiility coefficients ADC for dry mtter, protein, strch, totl phosphorus nd energy of the plnt-protein sources were mesured indirectly using Tle 1 Chemicl composition of the ingredients tested on dry mtter sis Fish mel Extruded Extruded Rpeseed mel Rpeseed pes lupin solvent mel het extrcted treted Dry mtter Ž % Ash Ž % Crude protein Ž % Crude ft Ž % Strch Ž % Gross energy Ž kjrg Totl phosphorus Ž % Phyttes Ž % Phytic cid Ž % Glucosinoltes Ž mmolrg Rest Ž % ADF Ž %. c NDF Ž %. c Glctosides Ž %. c High qulity Norwegin herring mel treted t low temperture. Rest, theoreticlly corresponding to lignin, monoscchrides, non-strch polyscchrides nd oligoscchrides ws estimted s follows: 100yŽ moistureqshqcrude proteinqcrude ftqstrch.. c The vlues indicted for ADF, NDF nd -glctosides re the verges otined from out 20 smples of similr plnt-ingredients Ž UNIP nd CETIOM, personl communiction..

5 ( ) C. Burel et l.raquculture chromic oxide s n inert trcer y the method of sustitution ŽSugiur et l., 1998; Bureu et l Two reference diets were prepred for trout nd turot, respectively, contining 1% chromic oxide. The test diets were mde y mixing 70% of the reference diet mixture nd 30% of the respective plnt-ingredient to e tested s shown in Tle 2. Pellets Ž B 4 mm. were prepred using power press Simon-Hensen ŽSimon-Hensen, Hollnd; dry pelleting.. In ll the mesurements, fish were fed y hnd to the reference or the test diets to pprent stition in one dily mel. The digestiility mesurements in rinow trout Ž Oncorhynchus mykiss. were crried out in the INRA fcilities t St Pee-sur-Nivelle Ž Frnce. using 10 cylindro-conicl tnks Ž cpcity: 60 l; wter-flow rte: 5 lrmin. supplied with recycled freshwter Žtemperture 16.58C.. Twenty rinow trout Ž out 100 g ech. were rndomly llocted to ech tnk. Fish were sumitted to 1-week dpttion period to the experimentl conditions Ž12 h of light:12 h of drk. nd experimentl diets. Then, fecl smples were collected for 1 Tle 2 Ingredients nd chemicl composition of diets used in the digestiility mesurements Diets Rinow trout Turot Ref. 1 Test 1 Test 2 Test 3 Test 4 Ref. 2 Test 1 Test 2 Test 3 Test 4 Ingredients (%) Extruded pes Extruded lupin Rpeseed mel, solvent-extrcted Rpeseed mel, het-treted Fish mel Geltinised whet strch Fish oil Vitmin mixture Minerl mixture Sodium lginte Chromic oxide Chemicl composition Dry mtter Ž % Crude protein Ž %DM. Strch Ž % DM Gross energy Ž kjrg DM. Phosphorus Ž %DM. As per Ntionl Reserch Council Ž NRC. Ž Ingormgrkg diet: clcium cronte Ž 40% C., 1.12 g; mgnesium oxide Ž 60% Mg., 0.62 g; ferric citrte, 0.1 g; potssium iodide Ž 75% I., 0.2 mg; zinc sulphte Ž 36% Zn., 0.2 g; copper sulphte Ž 25% Cu., 0.15 g; mngnese sulphte Ž 33% Mn., 0.15 g; disic clcium phosphte Ž 20% C, 18% P., 2.5 g; colt sulphte, 1 mg; sodium selenite Ž 30% Se., 1.5 mg; KCl, 0.45g; NCl, 0.2 g.

6 290 ( ) C. Burel et l.raquculture week from duplicte groups of fish per dietry tretment, using n utomtic fecl collector Ž Chouert et l., nd the collected fecl smples were frozen dily. The mesurements in turot Ž Psett mxim. were crried out in the IFREMER fcilities t Brest Ž Frnce., using 10 cylindro-conicl tnks Žcpcity: 500 l; wter-flow rte: 5 lrmin. supplied with fresh thermo-regulted sewter Ž slinity: 35, 168C.. Thirty-five turots Ž out 110 g ech. were rndomly llocted to ech tnk. Following 2-week period of dpttion to rering conditions Ž 12 h of light:12 h of drk. nd experimentl diets, fecl smples were collected from the two groups of fish per dietry tretment over 1 week, using the feces settling column system similr to the one descried in Cho et l. Ž ut dpted to cylindro-conicl tnks. Smples, constituted of feces nd residul wter, were centrifuged in order to recover the nitrogen compounds in suspension, nd kept frozen. The feces of turot hve tendency to loose their consistency in the wter-column. In order to prevent this disintegrtion, higher proportion of inder Ž lginte. ws dded in the turot diets compred to the trout diets Ž see Tle 2.. Pooled feces from ech group of fish were freeze-dried prior to the nlysis for chromic oxide, protein, ft, energy, sh nd phosphorus content. ADCs of the reference diet were clculted ccording to Mynrd nd Loosly Ž 1969.: ADC of dry mtter of diet Ž %. s100= w1yž dietry Cr O rfecl Cr O.x ADC of nutrients nd energy of diet Ž %. s100= w1yž dietry Cr O rfecl Cr O = Ž fecl nutrient or energy concentrtionrdietry nutrient or energy concentrtion.x The ADC of dry mtter, nutrients nd energy in the tested ingredients were clculted Ž. s follows Sugiur et l., 1998 : ADC of dry mtter of test ingredient Ž %. sžadc of the test diety0.7=adc of the reference diet. r0.3 ADC of nutrient or energy of test ingredient Ž %. swžnutrient or energy concentrtion in test diet=nutrient or energy ADC of the test diet. yž0.7=nutrient or energy concentrtion in reference diet = nutrient or energy ADC of the reference diet.xrž0.3 = nutrient or energy concentrtion in ingredient. All vlues re expressed per unit of dry mtter. As ingredients were weighed nd mixed with the reference diet on s fed sis Ž30% of the plnt-protein source nd 70% of the reference diet., the rtio 3:7 ws corrected for the clcultion for ech test diet tking into ccount the dry mtter contents of the test ingredient nd of the reference diet Anlyticl methods Anlyses of ingredients, diets, nd freeze-dried fecl smples were mde following Ž. the usul procedures AOAC, 1995 : dry mtter fter drying t 1058C for 24 h; sh y

7 ( ) C. Burel et l.raquculture comustion t 5508C for 12 h; protein Ž N=6.25. y the Kjeldhl method fter cid digestion; gross energy in n ditic om clorimeter Ž Prr Instruments, Moline IL.; ft fter extrction with petroleum ether y the Soxhlet method. Strch ws mesured y n enzymtic method Ž Thivend et l., using glucomylse nd glucose oxidse. Chromic oxide in the diet nd feces ws determined ccording to Bolin et l. Ž Totl phosphorus ws mesured y spectrophotometric nlysis of the phosphovndomolydte complex fter minerliztion nd cid digestion Ž AFNOR, Phytic cid nd phytte contents were determined ccording to Dvies nd Reid Ž Dt nlysis Dt re presented s mens with stndrd error. To test the effect of the ingredients for ech species, dt were sujected to one-wy nlysis of vrince Ž P-0.05., nd when pproprite, mens were compred y the Tukey s multiple rnge test or y the Student s t-test. 3. Results The ADC vlues otined with the two reference diets for protein nd strch re from fish mel nd geltinised whet strch, respectively, which re the min components of these reference diets. Hence, these vlues cn e compred with those otined from the plnt-ingredients tested Ž Tle 3.. Tle 3 ADC Ž %. of the nutrients nd energy of plnt-ingredients in rinow trout nd turot, nd comprison, when possile, with those of fish mel nd geltinised whet strch contined in the reference diet. Fish mel Geltinised Extruded Extruded Rpeseed mel, Rpeseed mel, strch pes lupin solvent-extrcted het-treted Trout Dry mtter 66.3" " " "3.1 NS Protein 89.2" " " " "1.5 P Energy 68.9" " " "3.1 P Strch 98.3" "4.8 P Phosphorus 42.6" " " "2.6 P Turot Dry mtter c 71.5"4.8 c 80.5" " "4.9 P Protein 90.8" " " " "3.4 P Energy 77.7"2.5 c 85.1" "4.0 c 80.9"0.9 P Strch 81.6" "2.5 NS Phosphorus c )100 c ) " "4.8 P ADC vlues re given s mens Ž ns2. with stndrd error. Superscript letters indicte sttisticl differences Ž one wy ANOVA nd Tukey s multiple rnge test or t-test. etween ADC vlues, relted to the ingredients tested for ech species. Mens with no common letter re significntly different Ž P

8 292 ( ) C. Burel et l.raquculture In turot, the digestiility of dry mtter ws significntly lower for the two rpeseed mels, especilly the solvent-extrcted one, compred to the extruded pes nd extruded lupin. No significnt difference ws oserved in rinow trout. In rinow trout, the ADC of protein from ll the plnt-ingredients ws comprle to tht from fish mel, nd even significntly higher in the cse of extruded lupin. In turot, the highest ADC vlues of protein were lso recorded for extruded lupin, ut vlues were not significntly different thn those of extruded pes, het-treted rpeseed mel nd fish mel. The ADC of proteins ws significntly lower for the solvent-extrcted rpeseed mel. The digestiility of the energy of the extruded pes ws significntly lower thn tht of the extruded lupin nd solvent-extrcted rpeseed mel in rinow trout. In turot, the ADC vlues of energy of the solvent-extrcted rpeseed mel were significntly lower thn those of the other plnt-ingredients. Digestile energy of extruded pes ws lso low in turot, ut differences were only significnt when compred to tht of extruded lupin. The digestiility of pe strch ws significntly lower thn tht of geltinised whet strch in trout. In rinow trout, the digestiility of phosphorus ws significntly higher for extruded lupin compred to tht of ll the other plnt-ingredients. The lowest digestiility of phosphorus ws oserved for the solvent-extrcted rpeseed mel. In turot, the vlues were significntly higher for extruded lupin nd extruded pes thn those of other ingredients. The digestiility of phosphorus of the solvent-extrcted rpeseed mel ws lso lower thn tht of the het-treted rpeseed mel. 4. Discussion In some cses, high vriility ws oserved etween the ADC vlues otined for the two groups of fish Ž n s 2. used per dietry tretment Žcoefficients of vrition, CV, up to 19.3%.. As lredy suggested y De l Noue et l. Ž 1980., greter numer of replictes would hve provided higher sttisticl power for dt nlyses. Besides, given tht two different methods of fecl collection were used, it is lso not resonle to drw conclusions s to whether the differences mong ADC vlues for trout nd turot were species-relted. Protein from extruded pes, extruded lupin nd het-treted rpeseed mel ppered to e digested y rinow trout nd turot s efficiently s those of high qulity Norwegin fish mel, in good greement with the dt of Sullivn nd Reigh Ž in hyrid striped ss. ADC of protein ws high for these plnt-ingredients in oth species, nd even significntly higher thn tht of the fish mel in the cse of extruded lupin in trout, in ccordnce with the dt of Hughes Ž nd Bngoul et l. Ž ADC of protein from solvent-extrcted rpeseed mel hd digestiility similr to tht of the fish mel in trout, ut in turot, their digestiility ws significntly lower. This would suggest tht turot re more sensitive to ANFs contined in rpeseed mel, lthough the ctivity of these fctors ws reduced y the therml tretment. The levels of GLS were 26 nd 40 mmolrg in het-treted nd solvent-extrcted rpeseed mel, respectively. Indeed, significnt decrese of the digestiility of protein is oserved in rt fed diets

9 ( ) C. Burel et l.raquculture contining progoitrin, epiprogoitrin or gluconpin Ž Bille et l., 1983; Bjerg et l., 1989., ll present in rpeseed, ut in smller mounts, following therml tretment. The digestiility of protein hs lso een found to e lower in common crp when isothiocyntes Ž hydrolytic products of GLS. were dded to the feed ŽHossin nd Juncey, The digestiility of strch contined in extruded pes ws lower Ž83% in trout nd 75% in turot. thn tht of geltinised whet strch in oth species, lthough it ws not significnt in turot. These results suggest lower level of geltinistion in the strch of extruded pes. Digestiility of strch is lso known to decrese with incresing dietry strch levels in trout Ž Bergot, In our cse, the reference diets contined 17% nd 8% of geltinised whet strch, nd the diets contining pes contined 27% nd 21% of strch from pes, for trout nd turot, respectively. It might e dvisle to express the digestiility of one type of strch for given level of dietry incorportion. Our results re, nevertheless, in good greement with the dt of Jollivet et l. Ž reporting high ADC vlues Ž 75 83%. for cooked cornstrch in turot, with vlues comprle to those of Bergot nd Breque ` Ž in trout. In trout, there ws no significnt difference in the digestiility of dry mtter mong the plnt-ingredients, due likely to the low sttisticl power of the experiment. The digestiility of the energy from pes ws significntly lower thn tht of the extruded lupin nd solvent-extrcted rpeseed mel. This my e relted to the fct tht energy from pes is minly from strch, which is generlly less digestile thn protein or ft. In ddition, pe seeds were not dehulled nd our own unpulished results hve shown tht dehulling improves the digestiility of dry mtter nd energy of this foodstuff. In turot, the significnt differences were found etween the plnt-ingredients in the ADC of dry mtter. The digestiility of energy for this species did not follow the sme pttern: the mjor difference ws tht the digestiility of the energy from extruded pes ws lower thn tht for the het-treted rpeseed mel. The imperfect prllelism etween the ADC vlues of dry mtter nd those of energy is ttriutle to the different gross energy contents of crohydrte nd protein; s mentioned ove, energy is minly otined from crohydrte Ž strch nd other scchrides. in extruded pes, insted of protein s in rpeseed mels nd lupin. The low digestiility of dry mtter nd energy of the solvent-extrcted rpeseed mel found in turot ws proly due to the high fire Žcid detergent fires Ž ADF. nd neutrl detergent fires Ž NDF.. content of rpeseed mel Ž Tle 1., s lso shown y Hilton nd Slinger Ž Bngoul et l. Ž reported tht the extrusion of lupin improved the utilistion of the N-free extrcts in rinow trout. These uthors suggested tht this improvement ws relted to higher rekdown of the cell wlls, llowing etter ccess of the digestive enzyme to the cell components, ndror to prtil degrdtion of -glctosides. Following extrusion t high temperture, decrese of 30% of the concentrtion of these compounds ws oserved y Melcion Ž Het tretment seems to lso hve eneficil effect on the utilistion of dry mtter nd energy in rpeseed mel. Indeed, the ADC vlues otined with the het-treted mel were higher thn those otined with the solvent-extrcted mel. In ddition, Gomes et l. Ž found high digestiility vlues in trout for co-extruded product of mixture of rpeseed nd pes. However, n effect of GLS contined in higher proportion in the

10 294 ( ) C. Burel et l.raquculture solvent-extrcted rpeseed should lso e considered in turot. Hossin nd Juncey Ž found decrese in dry mtter digestiility in common crp when fed feed supplemented with isothiocyntes. In trout, no significnt difference ws found mong the two rpeseed mels for the digestiility of dry mtter nd energy. The ADC vlues otined in this species were much higher thn those reported y Higgs et l. Ž 1996., ut similr to those found y Hilton nd Slinger Ž nd Adou Dde et l. Ž The ADC vlues of phosphorus from plnt-ingredients, especilly extruded pes nd lupin, were clerly over-estimted in turot. Literture reports phosphorus vilility of 19 58% for severl fish species including rinow trout for plnt-products such s rice nd soyen mel Ž Lll, This over-estimtion my e cused y the leching of this compound from feces in the column efore smpling. The leching of phosphorus from feces could induce stronger over-estimtion of its ADC vlues in the test diets contining pes nd lupin thn in the reference diet ecuse of the very low concentrtion of this nutrient in these plnt-ingredients. Secondly, the increse of the ADC vlues of this component in the test diets compred to the reference diet could e not only relted to its higher vilility in the 30% of pes or lupin, ut lso to n improvement of the digestiility of the phosphorus from the 70% of reference diet. The incorportion of plnt-ingredients in the diet is reported to ffect the intestinl trnsittime, due to the presence of fires nd sugrs Ž Storekken et l., In ddition, n increse of the sorption of phosphorus t the intestinl level, due to its lower concentrtion in the lupin or pes-sed diets might e lso n explntion. Despite such n over-estimtion of phosphorus vilility in turot, our dt suggest tht the ville phosphorus ws lower in the rpeseed mels, especilly in the solvent-extrcted mel, thn in the extruded lupin in oth fish species. Rpeseed mels used here hd higher level of phytic cid Ž % DM., in tune with literture dt Ž % DM; Higgs et l., 1996., thn lupin mel Ž 1.3% DM.. Phosphorus in the phytte form is known to e unville to fish, which hve no endogenous or microil phytse in their intestinl trct Ž Lll, Phytse is lso present in plnt seeds not sumitted to therml tretment, ut its ctivity is low Ž IUrkg. in crude pes, lupin, or in rpeseed mel, compred with those of whet or rye Ž up to 8000 IUrkg. Ž Pointillrt, The lower ADC vlues of phosphorus from the solvent-extrcted rpeseed mel compred to those of the het-treted mel my e due to its higher GLS content. Hossin nd Juncey Ž indeed showed decline in sh digestiility with high isothiocynte levels in the feed. Higher ADC vlues were oserved for the ingredient Ž extruded lupin. hving the lowest content of phytic cid nd phyttes, ut lso of totl phosphorus. This rgues in fvour of the hypothesis tht the lower the dietry concentrtion in phosphorus, the etter is its digestiility, in greement with the oservtions of Vielm nd Lll Ž in Atlntic slmon nd of Breves nd Schroder Ž in terrestril vertertes. The results otined with extruded pes re more difficult to explin ecuse they were not in ccordnce with those of the extruded lupin in rinow trout. How fr the ADC of phosphorus is ffected y dietry phosphorus level nd y the phytic cid in fish remins to e investigted. In conclusion, of the three plnt protein sources tested here, extruded lupin ppers to e the most promising sustitute for fish mel in the diets of oth trout nd turot. Extruded whole pes pper to hve lower digestiility of its protein nd phosphorus

11 ( ) C. Burel et l.raquculture in trout, of its dry mtter in turot, nd of its energy in oth species. It might e dvisle to remove the hulls of the pe seeds efore extrusion in order to improve the digestiility of energy. Finlly, the use of rpeseed mel, despite much progress in genetic engineering nd processing technologies, ppers limited. It is s yet difficult to point out which of the following fctors, high fire content, phytic cid or GLS, is individully or collectively involved. It might lso e of interest to study the effect of extrusion on nutrientrenergy digestiility of rpeseed mel. Acknowledgements This work hs een prtilly supported y the CETIOM nd y the UNIP. The uthors grtefully cknowledge the skilled technicl ssistnce of D. Blnc, H. Le Delliou nd P. Peyrotte. References Adou Dde, B., Aguirre, P., Blnc, D., Kushik, S.J., Incorportion du colz 00 sous forme de tourteu ou d mnde dns les liments de l truite rc-en-ciel Ž Oncorhynchus mykiss.: performnce zootechnique et digestiilite. Bull. Fr. Piscic. 317, AFNOR, Assocition Frnßise de Normlistion. Vol Aliments des Animux-Dosge du phosphore totl Methode spectrophotometrique ŽAniml feeding stuffs Determintion of totl phosphorus content-spectrophotometric method.. AFNOR, Norme frnßise enregistree 80133, ISOrDIS 6491 method, Pris. AOAC, Agriculture Chemicls; Contminnts, Drugs. 16th edn. Officil Methods of Anlysis of AOAC Interntionl vol. 1 AOAC Interntionl, Arlington, VA. Bngoul, D., Prent, J.P., Vells, F., Nutritive vlue of white lupin Ž Lupinus lus vr Lutop. fed to rinow trout Ž Oncorhynchus mykiss.: effects of extrusion cooking. Reprod., Nutr., Dev. 33, Bergheim, A., Sveier, H., Replcement of fish mel in slmonid diets y soy mel reduces phosphorus excretion. Aqucult. Int. 3, Bergot, F., Prolemes ` prticuliers poses pr l utilistion des glucides chez l truite rc-en-ciel. wprticulr prolems cused y the use of crohydrtes in rinow troutx Ann. Nutr. Aliment. 33, Bergot, F., Breque, ` J., Digestiility of strch y rinow trout: effects of physicl stte of strch nd of the intke level. Aquculture 7, Bille, N., Eggum, B.O., Jcosen, I., Olsen, O., Sorensen, H., Antinutritionl nd toxic effects in rts of individul glucosinoltes Ž "myrosinses. dded to stndrd diet. J. Anim. Physiol. Anim. Nutr. 49, Bjerg, B., Eggum, B.O., Jcosen, I., Otte, J., Sorensen, H., Antinutritionl nd toxic effects in rts of individul glucosinoltes Ž "myrosinses. dded to stndrd diet Ž 2.. J. Anim. Physiol. Anim. Nutr. 61, Bolin, D.W., King, R.P., Klostermn, E.W., A simplified method for the determintion of chromic oxide Ž Cr O. 2 3 when used s n index sustnce. Science 116, Bond, D.A., Duc, G., Plnt reeding s mens of reducing ntinutritionl fctors in grin legumes. In: vn der Poel, A.F.B., Huismn, J., Sini, H.S. Ž Eds.., Second Interntionl Workshop on Antinutritionl Fctors Ž ANFs. in Legume Seeds, Recent Advnces of Reserch in Antinutritionl Fctors in Legume Seeds, 70, Wgeningen, Hollnde, 1993, 1 3 decemre. EAAP Puliction, The Netherlnds, pp

12 296 ( ) C. Burel et l.raquculture Breves, G., Schroder, B., Comprtive spects of gstrointestinl phosphorus metolism. Nutr. Rev. 4, Bureu, D.P., Hrris, A.M., Cho, C.Y., Apprent digestiility of rendered niml protein ingredients for rinow trout Ž Oncorhynchus mykiss.. Aquculture 180, Cin, K.D., Grling, D.L., Pretretment of soyen mel with phytse for slmonid diets to reduce phosphorus concentrtions in htchery effluents. Prog. Fish-Cult. 57, Cho, C.Y., Cowey, C.B., Wtne, T., Finfish Nutrition in Asi. Methodologicl Approches to Reserch nd Development. Interntionl Development Reserch Centre, Ottw, Ont. Pul. No. IDRC Chouert, G., De l Noue, J., Luquet, P., Digestiility in fish: improved device for the utomtic collection of feces. Aquculture 29, Dvies, N.T., Reid, H., An evlution of the phytte, zinc, copper, iron nd mngnese contents of, nd Zn vilility from, soy-sed textured-vegetle-protein met-sustitutes or met-extenders. Br. J. Nutr. 41, De l Higuer, M., Grci-Gllego, M., Snz, A., Crdenete, G., Surez, M.D., Moyno, F.J., Evlution of lupin seed mel s n lterntive protein source in feeding of rinow trout ŽSlmo girdneri.. Aquculture 71, De l Noue, J., Chouert, G., Pgniez, B., Blnc, J.M., Luquet, P., Digestiilite chez l truite rc-en-ciel Ž Slmo girdneri. lors de l dpttion ` un nouveu regime limentire. Cn. J. Fish. Aqut. Sci. 37, Fenwick, G.R., Spinks, E.A., Wilkinson, A.P., Heney, R.K., Legoy, M.A., Effect of processing on the ntinutrient content of rpeseed. J. Sci. Food Agric. 37, Ferrndo, R., Blum, J.C. Ž Eds.., L limenttion des nimux monogstriques: porc, lpin, volille. wnutrition of monogstric nimls: pig, rit, poultryx 2nd edn. INRA, Pris Ž Frnce., 293 pp. Gomes, E.F., Corrze, G., Kushik, S., Effects of dietry incorportion of co-extruded plnt protein Ž rpeseed nd pes. on growth, nutrient utiliztion nd muscle ftty cid composition of rinow trout Ž Oncorhynchus mykiss.. Aquculture 113, Gomes, E.F., Kushik, S.J., Incorportion of lupin seed mel, colzpro or triticle s proteinrenergy sustitutes in rinow trout diets. In: Proc. Third Int. Symp. on Feeding nd Nutr. in Fish, To, Tokyo University, Jpn, 1989, 28 out 1er septemre. pp Gomes, E.F., Rem, P., Kushik, S.J., Replcement of fish mel y plnt proteins in the diet of rinow trout Ž Oncorhynchus mykiss.: digestiility nd growth performnce. Aquculture 130, Gouvei, A., Gomes, O.T., Rem, E., Effect of cookingrexpnsion of three legume seeds on growth nd food utiliztion y rinow trout. In: Kushik, S.J., Luquet, P. Ž Eds.., Fish Nutrition in Prctice, Birritz Ž Frnce.. INRA Collogues, 61, Pris, pp Hrdy, R.W., Sullivn, C.V., Cnol mel in rinow trout Ž Slmo girdneri. production diets. Cn. J. Fish. Aqut. Sci. 40, Higgs, D.A., Dosnjh, B.S., Bemes, R.M., Prendergst, A.F., Mwchirey, S.A., Decon, G., Nutritive vlue of rpeseedrcnol protein products for slmonids. In: Kent, N., Anderson, D. Ž Eds.., Proceedings of Estern Nutrition Conference, My DrtmouthrHlifx, Cnd, pp Higgs, D.A., McBride, J.R., Mrkert, J.R., Dosnjh, B.S., Plotnikoff, M.D., Clrke, W.C., Evlution of Tower nd Cndle rpeseed Ž Cnol. mel nd Bronowski rpeseed protein concentrte s protein supplements in prcticl dry diets for juvenile chinook slmon Ž Oncorhynchus tshwytsch.. Aquculture 29, Hilton, J.W., Cho, C.Y., Slinger, S.J., Effect of extrusion processing nd stem pelleting diets on pellets durility, pellet wter sorption, nd the physiologicl response of rinow trout Ž Slmo girdneri, R.. Aquculture 25, Hilton, J.W., Slinger, S.J., Digestiility nd utiliztion of cnol mel in prcticl-type diets for rinow trout Ž Slmo girdneri.. Cn. J. Fish. Aqut. Sci. 43, Hossin, M.A., Juncey, K., Toxic effects of glucosinolte Ž llyl isothiocynte. Žsynthetic nd from mustrd oilcke. on growth nd food utiliztion in common crp. Indin J. Fish. 35, Hughes, S.G., Assessment of lupin flour s diet ingredient for rinow trout Ž Slmo girdneri.. Aquculture 71, Jollivet, D., Gudn, J., Metiller, R., Influence du tritement de l midon et de son tux d incorpor-

13 ( ) C. Burel et l.raquculture tion insi que de l temperture et du rtionnement sur l digestion chez le turot ŽScophthlmus mximus, L.. ŽSome effects of physicl stte nd dietry level of strch, temperture nd mel size on turot digestive processes.. ICES, C.M. 1988rF:25, Mriculture Commitee, 17 pp. Kushik, S.J., Use of lterntive protein sources for intensive rering of crnivorous fishes. In: Flos, R., Tort, L., Torres, P. Ž Eds.., Mediterrnen Aquculture. Ellis Horwood, Chichester, pp Kushik, S.J., Crvedi, J.P., Llles, J.P., Sumpter, J., Fuconneu, B., Lroche, M., Prtil or totl replcement of fish mel y soyen protein on growth, protein utiliztion, potentil estrogenic or ntigenic effects, cholesterolemi nd flesh qulity in rinow trout. Aquculture 133, Lll, S.P., Digestiility, metolism nd excretion of dietry phosphorus in fish. In: Cowey, C.B., Cho, C.Y. Ž Eds.., Nutritionl Strtegies nd Aquculture Wstes. Proceedings of the First Interntionl Symposium on Nutritionl Strtegies in Mngement of Aquculture Wstes, 1991, University of Guelph, Guelph, Ontrio, Cnd. pp Letherlnd, J.F., Hilton, J.W., Slinger, S.J., Effects of thyroid hormone supplementtion of cnol mel-sed diets on growth, nd interrenl nd thyroid glnd physiology of rinow trout ŽSlmo girdneri.. Fish Physiol. Biochem. 3, Mmrini, M., Roem, A., Crvedi, J.P., Llles, J.P., Kushik, S.J., Effects of replcing fish mel y soy protein concentrte nd of DL-methionine supplementtion in high energy extruded diets on growth nd nutrient utilistion in rinow trout, Oncorhynchus mykiss. J. Anim. Sci. 77, Mwson, R., Heney, R.K., Zdunczyk, Z., Kozlowsk, H., Rpeseed mel-glucosinoltes nd their ntinutritionl effects: Prt 7. Processing. Die Nhrung 39 Ž. 1, Mynrd, L.A., Loosly, J.K., Animl Nutrition. 6th edn. McGrw-Hill, New York. McCurdy, S.M., Mrch, B.E., Processing of cnol mel for incorportion in trout nd slmon diets. JAOCS 69, Melcion, J.-P., Oleo-protegineux et cuisson-extrusion. wcooking-extrusion of plnts rich in oil nd proteinsx In: Colonn, P. Ž Ed.., Cuisson-extrusion, 1986, Septemer, Nntes, Frnce. INRA, Pris, pp Melcion, J.-P., vn der Poel, A.F.B., Process technology nd ntinutritionl fctors: principles, dequcy nd process optimiztion. In: Vn der Poel, A.F.B., Huismn, J., Sini, H.S. Ž Eds.., Second Interntionl Workshop on Antinutritionl Fctors Ž ANFs. in Legume Seeds, Recent Advnces of Reserch in Antinutritionl Fctors in Legume Seeds, 1993, 1 3 Decemer, Wgeningen, The Netherlnds. EAAP Puliction, pp Moyno, F.J., Crdenete, G., De l Higuer, M., Nutritive vlues of diets contining high percentge of vegetle proteins for trout, Oncorhynchus mykiss. Aqut. Living Resour. 5, Ntionl Reserch Council Ž NRC., Nutrient Requirements of Fish. Ntionl Acdemic Press, Wshington, DC. Plmer, T.N., Rymn, B.E., Studies on orl glucose intolernce in fish. J. Fish Biol. 4, Pointillrt, A., Phyttes, phytses: leur importnce dns l limenttion des monogstriques. wphyttes nd phytses: their relevnce in the feeding of pigs nd poultryx INRA Prod. Anim. 7, Roemer, P., Lupinus lus L., vlule future crop of old trdition. Grin Legumes 3, Singh, R.P., Nose, T., Digestiility of crohydrtes in young rinow trout. Bull. Freshwter Fish. Res. L. 17, 21 25, Tokyo. Smithrd, R.R., Eyre, M.D., The effects of dry extrusion of rpeseed with other feedstuffs upon its nutritionl vlue nd ntithyroid ctivity. J. Sci. Food Agric. 37, Storekken, T., Kvien, I.S., Sherer, K.D., Grisdle-Hellnd, B., Hellnd, S.J., Estimtion of gstrointestinl evcution rte in Atlntic slmon Ž Slmo slr. using inert mrkers nd collection of feces y sieving: evcution of diets with fish mel, soyen mel or cteril mel. Aquculture 172, Sugiur, S.H., Dong, F.M., Rthone, C.K., Hrdy, R.W., Apprent protein digestiility nd minerl vililities in vrious feed ingredients for slmonid feeds. Aquculture 159, Sullivn, A.J., Reigh, R.C., Apprent digestiility of selected feedstuffs in diets for hyrid striped ss Ž Morone sxtilis femle= Morone chrysops mle.. Aquculture 138, Tcon, A.G.J., Feed ingredients for crnivorous fish species: lterntives to fish mel nd other fishery resources. Food nd Agriculture Orgniztion of the United Ntions, FAO Fisheries Circulr 881 Rome, Itlie, 35 pp.

14 298 ( ) C. Burel et l.raquculture Teskeredzic, Z., Higgs, D.A., Dosnjh, B.S., McBride, J.R., Hrdy, R.W., Bemes, R.M., Jones, J.D., Simell, M., Vr, T., Bridges, R.B., Assessment of undephytinized nd dephytinized rpeseed protein concentrte s sources of dietry protein concentrte s sources of dietry protein for juvenile rinow trout Ž Oncorhynchus mykiss.. Aquculture 131, Thivend, P., Mercier, C., Guilot, A., Determintion of strch with glucomylse. In: Whistler, R.L., Bemiller, J.N. Ž Eds.., Methods in Crohydrte Chemistry vol. 4 Acdemic Press, New York, pp Vielm, J., Lll, S.P., Control of phosphorus homeostsis of Atlntic slmon Ž Slmo slr. in fresh wter. Fish Physiol. Biochem. 19, Yurkowski, M., Biley, J.K., Evns, R.E., Tchek, J.-A.L., Burton Ayles, G., Acceptility of rpeseed proteins in diets of rinow trout Ž Slmo girdneri.. J. Fish. Res. Bord Cn. 35,