Ideal amino acid profiles as a basis for feed protein evaluation

Transcription

1 Livestok Prodution Siene 64 (2000) lote/ livprodsi Idel mino id proiles s sis or eed protein evlution * S. Boisen, T. Hvelplund, M.R. Weisjerg Deprtment o Animl Nutrition nd Physiology, Dnish Institute o Agriulturl Sienes, Reserh Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmrk Reeived 23 Mrh 1999; reeived in revised orm 3 August 1999; epted 11 August 1999 Astrt The most importnt single tor eting the eiieny o protein utiliztion is the proile o digestile essentil mino ids entering the smll intestine. Assuming onstnt idel mino id proile o sored protein the requirements o ll mino ids n e lulted when the requirement o one individul mino id hs een determined. In non-ruminnts, the supply will e gretly inluened y the diet, ut less so in ruminnts due to the rumen miroil degrdtion o eed protein nd synthesis o miroil protein with high iologil vlue. However, the high-produing diry ow requires signiint mount o rumen espe protein. Thus, the proile o the undegrded eed protein ould inluene the proile o the mino ids entering the smll intestine to point t whih individul mino ids eome limiting. For non-ruminnts, lysine is usully the irst limiting mino id in eedstus. This hs led to the generl prtie o expressing the requirements or ll other essentil mino ids reltive to lysine. Alterntively, the mino id requirements n e expressed reltive to N. Then, dietry N required or synthesis o other N-ompounds is lso inluded. Moreover, the requirements o ll mino ids n e lulted when the N requirement hs een determined. However, this method nnot e used or ruminnts, euse the N requirement o rumen miroes my e higher thn the requirement o the niml. In the uture, omputerised niml models sed on sientiilly orret eed evlution systems oer the opportunity or seuring optiml eeding o rm nimls in reltion to their idel mino id proile or ll dierent purposes o prodution Pulished y Elsevier Siene B.V. All rights reserved. Keywords: Pig; Diry ow; Amino ids; Idel protein; Protein evlution 1. Introdution mrkedly euse o dierenes in ntomy nd digestive proesses. Thus, the signiint synthesis o The nutritionl vlue o individul dietry protein mino ids in the miroil ermenttion proesses soures or ruminnts nd non-ruminnts diers in the rumen my redue the importne o the dietry protein qulity or ruminnts signiintly. This hs een demonstrted y eeding ure s the *Corresponding uthor. Tel.: ; x: only N-soure to diry ows whih were still le to produe milk with norml mino id omposition E-mil ddress: sigurd.oisen@grsi.dk (S. Boisen) (Virtnen, 1966). Consequently, lterntive p / 00/ $ see ront mtter 2000 Pulished y Elsevier Siene B.V. All rights reserved. PII: S (99)

2 240 S. Boisen et l. / Livestok Prodution Siene 64 (2000) prohes re required to evlute the qulity o isoleuine, leuine, histidine, phenyllnine nd vldietry protein. ine. Common to oth niml types, however, is Arginine is lso n essentil mino id or mny undmentl demnd tht eed proteins must e niml speies, e.g. irds nd ish. However, mmdigestile, though the mino id requirements o mls, e.g. pigs nd ruminnts, synthesize rginine in high-produing diry ows put onstrints on the the ure yle where ure is produed rom surplus desired rte o protein hydrolysis y the rumen nitrogen. On the other hnd, most rginine produed miroes. in the ure yle is roken down nd some nimls Most nturlly ouring proteins re inherently (e.g. young pigs) need dietry supply (Fuller, highly digestile. However, in some eeds digestiili- 1994). Thereore, rginine is onsidered to e ty is impired y ompt protein struture or the semi-essentil mino id. However, in ll ommon presene o protese inhiitors, letins, tnnins nd diets rginine seems to e in onsiderle surplus other nti-nutritionl onstituents. Controlled heting s disussed lter. n ountert mny o these eets ut exessive Cystine nd tyrosine re lso onsidered s semiheting or inpproprite hemil tretment o eeds essentil mino ids s they n only e synthesized during proessing n redue digestiility y d- y nimls rom methionine nd phenyllnine, versely modiying physil struture nd hemil respetively. Thereore, the mino id requirements mke-up. The vilility o lysine nd other mino hve to inlude the sum o methionine 1 ystine ids is prtiulrly sensitive to proessing on- (sulphur mino ids) nd phenyllnine 1 tyrosine ditions due to the ormtion o Millrd produts nd (romti mino ids), respetively. In ddition, other mino id omplexes or produts t elevted ulilling the requirements o the sum lone my not tempertures (Boisen, 1998). On the other hnd, or e suiient euse methionine nd phenyllnine ruminnt eeds, onsiderle eorts hve een ous- nnot e synthesized rom ysteine nd tyrosine, sed on the possiility o reduing the vilility o respetively. dietry protein or the mirolor in the rumen y The remining eight mino ids, inluding hemil nd physil tretments nd still preserving lnine, sprti id, sprgine, glutmi id, high mino id digestiility in the smll intestine. glutmine, serine, glyine nd proline, n ll e The im o this pper is to disuss the opportunity synthesized rom metolites produed during the or using the idel mino id proile s undmen- oxidtion o gluose. Although severl ppers in the tl sis or evlution o the protein in eed or rm literture report eneiil eet o supplying some nimls. The pper ouses on the growing pig s o these mino ids in the diet (Heger et l., 1987; representtive o non-ruminnts nd on the high- Chung nd Bker, 1992; Kirhgessner et l., 1995), produing diry ow s representtive o rumin- their mount in ommon diets is generlly suiient. nts. Current estimtes o idel protein or these two An overview o the syntheti pthwys o nontegories o rm nimls nd options or uture essentil nd semi-essentil mino ids re indiimprovements in its use in eed evlution will lso ted, together with the essentil mino ids or the e disussed. pig in Fig. 1. The mino ids re urther grouped ording to their hemilly retive (or untionl) side hins. 2. Essentil nd non-essentil mino ids Proteins re omposed o 20 dierent mino ids, 3. The idel protein onept o whih nine nnot e synthesized y most niml speies. Thereore, ontinuous supply o these nine The mino id requirements o rm nimls re mino ids plus suiient nitrogen or synthesizing inluened y mny dierent tors inluding: (1) the other mino ids re essentil or mintenne popultion, i.e. weight, dily gin, sex nd genotype; nd prodution (growth). The nine essentil mino (2) environment nd (3) helth sttus (Moughn, ids re: Lysine, methionine, threonine, tryptophn, 1989; Fuller, 1991,1994). However, most hnges in

3 S. Boisen et l. / Livestok Prodution Siene 64 (2000) Fig. 1. Essentil, semi-essentil nd non-essentil mino ids or the growing pig grouped in reltion to their untionl groups. The syntheti routes or the semi-essentil nd non-essentil mino ids re lso indited. mino id requirements do not led to hnges in lysine. The rgument or using lysine hs een tht the reltive proportion o the dierent mino ids. lysine is usully the irst limiting mino id in the Thereore, the tul hnges n lmost exlusively diet nd is not used or the synthesis o other e onsidered to reer to the mount o lned N-ompounds. The ove deinition ws introdued protein, or idel protein or the niml. In idel or the growing pig y ARC (1981). protein eh essentil mino id is eqully limiting The deinition ws extended to inlude n optiml or perormne (i.e. mintenne nd prodution, rtio etween essentil nd non-essentil mino ids e.g. growth) in the tul eeding sitution, nd there (Wng nd Fuller, 1989). However, euse the is miniml surplus o N. Consequently, the ppli- mount o non-essentil mino ids is inluened y tion o n idel protein proile in diet ormultion is the omposition o these, orret deinition should lso vlule tool or minimizing N exretion rom rther inlude the requirement or non-essentil rm niml prodution without ny losses in per- mino id-n or simply the requirement or totl N ormne (Boisen, 1993). The idel protein is usul- (Boisen, 1997). Consequently, the proile o essentil ly deined s: mino ids should preerly e given reltive to N or reltive to rude protein (N ). The idel The peret rtio mong the essentil mino protein n lterntively e deined s: ids required or mintenne nd prodution. The peret rtio mong individul essentil Assuming onstnt idel mino id proile the mino ids nd N required or optiml perrequirements o ll essentil mino ids n e ormne. lulted when the requirement o one individul mino id hs een determined. Commonly, the From this deinition it lso ollows tht with mino id proile hs een expressed reltive to onstnt omposition o the idel protein the require-

4 242 S. Boisen et l. / Livestok Prodution Siene 64 (2000) ments or ll essentil mino ids n e lulted (Boisen nd Moughn, 1996). In the literture, when the N requirement (idel protein-n) hs een mny studies o idel protein proile in ommon diets determined. hve een sed on pprent digestile mino ids (e.g. Wng nd Fuller, 1990; Lenis et l., 1993; Tuitoek et l., 1997). However, vlues o pprent 4. Current estimtes o idel protein or rm digestiility my underestimte the digestiility o nimls low-protein soures (e.g. erels) nd in prtiulr the reltively lowest mino ids (e.g lysine in erel 4.1. The growing pig proteins nd sulphur mino ids in legume proteins). The proposl or n idel mino id proile or New pprohes or determining ilel digestiility the growing pig given y ARC (1981) ws sed on o mino ids in pig eedstus nd eed mixtures erlier studies o the requirements or the individul hve reently een desried (Boisen nd Moughn, essentil mino ids. However, these requirements 1996), nd it ws onluded tht true ilel dihve ommonly een determined y mesuring the gestiility o mino ids determined under stneet on perormne when dierent mounts o drdized onditions should generlly e used in eed supplementry mino ids re dded to sl diet evlution. Vlues or true (stndrdized) digestile onsisting o nturl ingredients. Consequently, the mino ids in single eedstus re, in ontrst to determined requirements o mino ids re inlu- vlues o pprent digestile mino ids, not inened y the ury o the determined vlues o luened y protein level nd re thereore dditive digestile (ville) mino ids in question in the in eed mixtures (Boisen, 1998). Furthermore, vlues sl diet (Suer nd Ozimek, 1986; Moughn et l., o true (stndrdized) digestile mino ids n e 1987). onsidered to orrespond to the determined mino id requirements whih over oth mintenne nd Aville dietry mino ids in the smll protein retion in the growing pig s determined intestine y Fuller nd oworkers (Wng nd Fuller, 1989; Estimtes o mino id requirements nd the Fuller et l., 1989). resulting idel mino id proile rely on severl From the disussion ove, it ollows tht in experimentl tors. erel-sed diets vlues o pprently digestile Firstly, they depend on hemil nlyses. In lysine my generlly underestimte the reltive prtiulr the sulphur mino ids, methionine nd mount o digestile lysine in the inl diets, nd ystine, re very suseptile to degrdtion during onsequently overestimte the ontriution o most the preeding id hydrolysis nd my e under- o the other mino ids in the ssumed idel protein estimted leding to n overestimtion o the require- in the experimentl diet. ment. Seondly, they depend on the tehnique nd Idel mino id proile lultion o the digestiility (vilility) o the Although the onept o idel protein hs een mino ids. Amino ids re only digested in the used ommonly during the lst two dedes preise smll intestine nd their digestiility needs to e mino id pttern or growing pigs hs not yet een determined t the terminl ileum (y istultion or inlly doumented. Thereore, severl dierent ptslughter tehnique) euse o miroil meto- terns re used. Tle 1 summrizes some idel lism in the hindgut. proteins given in the literture. The tle demon- Mesurements o ilel digestiility o mino ids strtes onsiderle dierenes etween the dierent re signiintly inluened y endogenous protein proposls. losses, nd vlues o pprent digestiility re there- As disussed ove, the mino id pttern given ore relted only to the speii protein level, or more reltive to N (1 kg rude protein orresponding to orretly, to the speii onentrtions o the in- 160 g N) ppers to e more inormtive due to the dividul mino ids in the experimentl diet inlusion o dietry N required or synthesis o other

5 S. Boisen et l. / Livestok Prodution Siene 64 (2000) Tle 1 1. These re ompred with the omposition in sow s Amino id proile (reltive to lysine) o idel protein or growing milk, whih hs een ound to e very onsistent pigs (Boisen et l., 1988) nd were suggested to hve A B C D E F G H een developed during the evolution to hve n idel Lysine pttern or sukling pigs. Most vlues re ompr- Met 1 Cys le exept those or sulphur mino ids (met 1 Threonine ys) nd threonine whih hve reltively higher Tryptophn Isoleuine requirement thn their ontents in sow s milk. These Leuine mino ids re hrteristilly very high in the Vline endogenous protein loss rom the digestion proesses Histidine in the gut o growing pigs (Boisen nd Moughn, Phe 1 Tyr ). Ater wening, due to the dietry hnge Arginine rom highly digestile nutrients in the milk to more A: ARC (1981); B: INRA (1984); C: NRC (1988); D: Wng nd more ier-rih diets, endogenous protein losses nd Fuller (1989); E: Fuller et l. (1989); F: Chung nd Bker inrese nd ontriute onsiderly to the totl (1992); G: Rhone Poulen (1993); H: Cole nd Vn Lunen (1994). mino id mintenne requirements o the growing pig. Consequently, growing pigs hve higher require- N-ompounds thn essentil mino ids. Further- ments or sulphur mino mino ids nd threonine more, the ury o the pttern does not rely on thn sukling pigs. On the other hnd, the pttern in orret estimte o the ville mount o one sow s milk or the other essentil mino ids pper prtiulr mino id, whih is prtiulrly pro- to e resonle estimte or growing pigs. Furlem with lysine. Not only in reltion to the ove thermore, due to the deposition o predominnt disussion on pprently digestile lysine ut lso in portion o the requirements or mino ids (out reltion to mny proessed oods, whih my ontin 80%), the mino id pttern o deposited protein in lower mounts o ville lysine thn ssumed. the growing pig is lso similr to tht o milk protein Besides, speii vlues or oth methionine nd (Tle 2). phenyllnine (rther thn simply sulphur mino Severl mino id ptterns or mintenne hve ids nd romti mino ids) need to e given or een suggested. The mintenne requirement or N omplete idel protein. n e mesured t N-equilirium (no gin or loss o Tle 2 shows some o the ptterns relulted N). However, this is muh more diiult to derom given vlues o N nd rom the vlues in Tle termine diretly or mino ids euse t N- Tle 2 Amino id omposition (g/160 g N) o idel protein or growing pigs A B C D E F G H Ftor Lysine Methionine Met 1 Cys Threonine Tryptophn Isoleuine Leuine Vline Histidine Phenyllnine Phe 1 Tyr A: ARC (1981); B: NRC (1988); C: Wng nd Fuller (1989); D: Fuller et l. (1989); E: Chung nd Bker (1992); F: Sows milk (Boisen et l., 1988); G: Deposited rom 20 to 90 kg live weight (Jørgensen et l., 1988); H: Proposed stndrd omposition (Boisen, 1997); Ftor: onversion tors rom N requirement to individul mino id requirements.

6 244 S. Boisen et l. / Livestok Prodution Siene 64 (2000) equilirium redistriution o tissue protein will this generl idel protein or growing pigs is our. Thus, utneous tissues inluding hir will suggested (Tle 2). In the tle is lso given the ontinue to grow (Fuller, 1994) nd rom the diges- onversion tors rom N to the individul mino tion proesses losses o endogenous protein will lso ids. From these tors the requirements or ll ontinue. To ompenste or this, musle protein will mino ids n e lulted rom mesurements o e degrded (De Lnge et l., 1989). As the pttern N requirements. o musle protein is onsiderly lower in sulphur mino ids nd threonine thn protein in hir nd Protein qulity o eeds endogenous losses, reltive surplus o ll other When the idel protein hs een estlished, essentil mino ids eomes ville. Conse- detiled inormtion out the protein qulity o quently, the experimentlly determined requirements single eedstus nd omplete diets n e otined or these mino ids my e more or less under- rom lultions o the ontriution o eh inestimted (Boisen, 1997). dividul mino id to the idel pttern (Tle 3). It ollows tht present knowledge o the speii The tle demonstrtes the well-known t tht requirements or mino ids or mintenne is erels re generlly low in lysine nd threonine, nd rther limited, lthough it is generlly ssumed tht mize lso in tryptophn, while legumes re low in the reltive requirements or mintenne inrese sulphur mino ids. These mino ids re lso during growth. On the other hnd, mintenne onsidered to e the irst limiting mino ids in pig requirements reltive to totl requirements seem to diets nd n ll e otined ommerilly s e reltively low, exept or sulphur mino ids, industril mino ids. O these, methionine is threonine nd tryptophn (Moughn, 1995). Further- produed synthetilly nd onsists o 50:50 more, the eiieny o utiliztion o ville dietry mixture o the D- nd L-orms (D,L-methionine), while mino ids or retion nd how this my hnge the other mino ids re miroilly produed nd during growth is unler. Thereore, it is suggested re 100% L-orm. tht, or prtil eed evlution, the idel protein The potentil or improving protein qulity (idel pttern or growing pigs is onsidered onstnt rom protein rtio) y mino id supplementtion n e 20 kg to slughter t 100 kg live weight. Bsed on exempliied y simple mixture o rley nd Tle 3 Protein qulity o ommon protein soures in pig eeds lulted rom the mino id pttern reltive to tht o idel protein Cerels Oilseed y-produts Others Brley Whet Mize SBM RSM SFM Whet Pe Fish rn mel Lysine Methionine Met 1 Cys Threonine Tryptophn Isoleuine Leuine Vline Histidine Phenyllnine Phe 1 Tyr Arginine IP rtio SBM: soyen mel; RSM: rpeseed mel; SFM: sunlower mel. Idel protein-n reltive to totl N. First limiting mino id.

7 S. Boisen et l. / Livestok Prodution Siene 64 (2000) Tle 4 Protein qulity (omposition o stndrdized digestile mino ids reltive to the idel mino id pttern) o eeds or growing pigs Brley Soyen mel Brley/ SBM diet Brley/ SBM 1 (SBM) (87:10) supplemented AA Lysine Methionine Met 1 Cys Threonine Tryptophn Isoleuine Leuine Vline Histidine Phenyllnine Phe 1 Tyr IP rtio Supplementtion per kg eed: 0.23 g lysine, 0.03 g methionine nd 0.09 g threonine. Idel protein-n reltive to totl N. First limiting mino id. soyen mel (Tle 4). The rtio o idel protein- limiting mino id is histidine nd not methionine N to totl N n e inresed rom 63 to 87% y s in Tle 4. This lso illustrtes tht the order o supplementing with lysine, threonine nd limiting mino ids my hnge. Consequently, methionine. The potentils nd limittions or im- when using ixed vlues the lulted order o proving the protein qulity o pig diets y mino id limiting mino ids my not lwys e orret or supplementtion is urther illustrted in Fig. 2. the tul eed. Although the omposition o the diets in Tle 4 nd In more omplex diets the protein qulity my e Fig. 2 re identil, the dt or digestile mino improved to more thn 90% y supplementtion with ids re rom dierent soures. In Fig. 2 the third the irst limiting mino id. However, in generl it Fig. 2. Amino id omposition reltive to idel protein o rley/ soyen mel pig diet. The igure illustrtes the potentils nd limittions or improving the protein qulity o pig diets y mino id supplementtion (Boisen, 1993). Let xis: Amino id ontriution to idel protein reltive to lysine in unsupplemented diet; right xis: Theoretil iologil vlue (BV) o dietry protein. The inrese in BV ter supplementtion o lysine nd threonine, respetively, is indited. The igure is sed on other dt thn those given in Tle 4. For urther inormtion see text.

8 246 S. Boisen et l. / Livestok Prodution Siene 64 (2000) n e onluded tht ter supplementtion o the wht extent is it possile to inluene the omirst two to three limiting mino ids, most o the position o the protein leving the rumen. It hs oten other essentil mino ids my eome limiting. een emphsized tht the omposition o duodenl Thereore, or proper mino id supplementtion o protein is rther onstnt due to high proportion o diets, ext knowledge o the ville dietry miroil protein whih ws erlier onsidered to e essentil mino ids, reltive to their requirements, very onstnt (Purser nd Buehler, 1966; Bergen et is neessry. However, ompred to the irst limiting l., 1968). On the other hnd, i the eed protein hs mino id, the requirements or the other essentil low degrdility in the rumen nd n mino id mino ids hve een muh less studied (NRC, omposition dierent rom the miroil protein, it 1998). my hve n impt on the mino id omposition o the outlow rom the rumen The diry ow Comprisons o the mino id omposition o the eed with tht o the duodenl protein rom 33 For ruminnts, the most importnt single tor dierent diets (Tle 5) lerly show tht metoeting the eiieny o protein utiliztion is, s or lism in the rumen leds to redued vrition in the monogstri nimls, the proile o digestile essen- onentrtions o the individul mino ids. Howtil mino ids entering the smll intestine. How- ever, onsiderle vrition remins whih my e ever, the supply o mino ids or sorption in the used y ontriutions rom dietry mino ids. smll intestine o ruminnts is mixture o unde- On the other hnd, in review o the literture Clrk grded dietry protein nd miroil protein pro- et l. (1992) ound vritions in the teril mino dued in the rumen. To hieve n idel protein t id ompositions o 441 smples olleted ter the duodenl level, it is neessry to lne the eeding 61 dierent diets, whih were generlly mino id omposition o the miroil protein out the doule those given in Tle 5. Still, the produed in the rumen with eed protein whih hs men mino id omposition ws very lose to tht esped degrdtion in the rumen. given in Tle 5 nd muh o the higher vrition n proly e sried to the dierent methods Amino id outlow rom the rumen used or isoltion nd nlysis. Tle 5 shows tht The mjor ontriution to duodenl protein low is the mino id omposition o isolted rumen miroil protein. A entrl question is thereore to teri, s well s the vrition o the individul mino Tle 5 Amino id omposition (g AAN/ 100 g AAN) in ruminnt diets, isolted rumen teri, endogenous protein nd duodenl ontent Feed Rumen teri Endogenous protein Duodenl ontent d Men CV Men CV Men CV Men CV Lysine Methionine Threonine Isoleuine Leuine Vline Histidine Phenyllnine Arginine Results or 33 dierent diets (Hvelplund nd Mdsen, 1989). Results rom 49 smples olleted ter eeding 24 dierent diets (Hvelplund, 1986). Vlues or duodenl endogenous low estimted y Lrsen et l. (2000). d Not determined CV: Coeiient o vrition.

9 S. Boisen et l. / Livestok Prodution Siene 64 (2000) ids, is very lose to tht o the duodenl ontent. testinl rude protein digestiility (mesured with the This indites tht the vrition in the mino id moile g tehnique) is lso ssumed to represent omposition o duodenl ontents is inluened y individul mino id digestiilities. vritions in the miroil popultion, s well s dietry protein Protein qulity o eeds In onlusion, these results demonstrte tht there A generl improvement o the protein qulity n e signiint dierenes in the mino id when ompring the mino id omposition o omposition o miroil protein produed in the duodenl low nd rumen teri with dietry rumen. Thereore, it is importnt to identiy the protein ws indited in Tle 5. In prtiulr the tors responsile or this vrition when prediting ontriution o lysine nd threonine, whih re oten the mino id proile o the miroil protein the irst limiting mino ids in diets or mmmls, produed ter eeding dierent diets. were ound to e onsiderly inresed in the duodenl protein low Aville mino ids in the smll intestine The idel mino id pttern or the diry ow n The digestiility in the smll intestine o indi- e onsidered to e losely relted to the omvidul mino ids rom miroil protein produed position o the ow s milk. The mino id requirey the rumen teri ppers to e quite onstnt ments or mintenne hve not een determined nd hs een determined to e out 85% or ll diretly or diry ows. However, tenttive estimino ids, exept or ystine, whih ws deter- mte n e otined rom generl vlue or mined to e only out 75% (Storm et l., 1983; mmmls relted to metoli weight (Fuller, 1991). Hvelplund nd Hesselholt, 1987). These results were For 500 kg ow produing 30 kg milk with 3.2% otined rom sheep y inusion o miroil protein protein, the lulted mino id requirements or nd orrespond, thereore, to the true digestiility, s mintenne y this method ount, or most mino endogenous losses re not onsidered to inluene the ids, or out 30% o the mino ids in the milk. mesurements. The lulted totl dily mino id requirements The rumen degrdility o protein s well s the re given in Tle 6. An lterntive lultion rom intestinl digestiility o undegrded protein rom the mintenne requirements suggested y Asplund dierent eedstus n e muh more vrile. In (1994) or sheep would result in higher vlues. reent study y Weisjerg et l. (1996), whih The lultions were sed on the ollowing inluded 15 dierent onentrtes, lrge dierenes ssumptions: in intestinl mino id digestiilities were oserved mong dierent onentrtes, with the highest or (i) the dietry intke meets the energy requirepotto protein (Protmyl, 0.98) nd the lowest or ments or mintenne nd prodution o 30 kg ottonseed ke (0.84). With respet to individul milk, mino ids, glutmi id nd rginine hd higher, (ii) miroil prodution in the rumen is 125 g nd threonine nd glyine lower, digestiilities om- mino id per kg ermented rohydrtes, pred to totl mino ids, wheres the reminder o (iii) the mino id omposition o miroil the individul mino ids were similr to totl protein orresponds to the one used in the Nordi mino ids. In generl, the digestiility o the mino protein evlution system (Mdsen et l., 1995), ids, mesured y the moile nylon g tehnique, (iv) ll mino ids in miroil protein re 85% my oten e very similr to tht determined or digestile, rude protein in onentrtes (Weisjerg et l., 1996) (v) there re no hnges in the ody mino id s well s in roughges (Ski et l., 1996), lthough pool. higher digestiility vlues hve een reported or mino ids thn or rude protein (Skorko-Sjko et The lulted miroil protein supply with digestl., 1994). As mino id digestiility is the vlue ile essentil mino ids is or ll mino ids less required in modern protein evlution systems, in- thn the mount required (Tle 6).

10 248 S. Boisen et l. / Livestok Prodution Siene 64 (2000) Tle 6 Estimtes o the irst limiting mino id in dierent eedstus or ulilling the mino id requirements (g AA/ dy) o the diry ow rom ruminlly undegrded eed protein Supply rom ruminlly undegrded protein Requirements Miroil Deiit Brley Mize SBM RSM Fishmel Mixture supply d e Lysine Methionine Threonine Isoleuine Leuine Vline Phenyllnine Mintenne 1 prodution o 30 kg milk with 3.2% protein (no hnges in ody protein mss). Predited outlow rom the rumen o digestile miroil mino ids when the dietry energy supply ulils the requirements. Soyen mel. d Rpeseed mel e Composition,%: rley, 10; mize, 30; rpeseed mel, 30; ish mel, 20; grss, 10. First limiting mino id. The deiit in the requirements must thereore e duodenl low the perentge o diets in whih the met rom undegrded dietry protein. Dierent eed mino id is reltively undersupplied is lulted proteins hve dierent mino id omposition nd (Tle 7). Apprently, the most requently limiting digestiility nd onsequently dierent potentil or mino id is leuine whih is lulted to e supplying the ow with the mino ids tht re in undersupplied y 89% o the diets, while methionine, short supply. This is lso illustrted in Tle 6 where lysine nd threonine were ound to e undersupplied the mounts o supplementry digestile mino ids y 68, 34 nd 15% o the diets, respetively. This required to meet the requirements o the irst limiting inding is rther surprising, euse leuine hs, to mino id re lulted or dierent eeds. These the uthors knowledge, never een experimentlly lultions ssume tht the mino id proile o the ound to e the irst limiting mino id. On the undegrded protein is the sme s tht o the intt other hnd, Tle 7 lso demonstrtes tht the protein. Furthermore, it is ssumed tht eh in- ontriutions o methionine nd lysine to the duodedividul mino id is digested in the smll intestine nl low re muh more vrile thn tht o leuine, to the sme extent lthough this my not lwys e inditing tht the supply o the two ormer mino the se s disussed erlier. ids is muh more inluened y diet omposition Tle 6 illustrtes tht the irst limiting mino id thn tht o leuine. Most proly, methionine is diers mong eeds. For rpeseed mel nd ishmel, the irst limiting mino id in diets in whih leuine ws irst limiting. For grins, inluding soyen mel is the min protein, wheres lysine is rley, ots nd mize the lultions showed tht the irst limiting mino id when erel protein lysine ws the irst limiting mino id. For soyen predomintes. Consequently, leuine would e exmel, methionine ws identiied s the irst limiting peted to generlly e the seond limiting mino mino id. id. This is in greement with the inding o Fisher In Tle 7 n idel mino id proile is lulted (1972). on the sis o the requirements given in Tle 6. The proportions o methionine nd lysine in the The idel proile is ompred with vlues estimted idel mino id proile shown in Tle 7 re or endogenous protein (Lrsen et l., 2000) nd somewht lower thn the vlues proposed y Ruldiretly determined vlues or duodenl low re- quin et l. (1993). However, it should e noted tht sulting rom 33 diets (Hvelplund, 1986). Bsed on the vlues given in Tle 7 re in % o totl mino the vrition determined or eh mino id in the ids, wheres those given y Rulquin et l. (1993)

11 S. Boisen et l. / Livestok Prodution Siene 64 (2000) Tle 7 Amino id proile (g AA/100 g AA ) o idel protein ompred with those o endogenous protein nd duodenl low nd lulted per ent o diets in whih the mino ids in duodenl low were reltively undersupplied when ompred to the idel protein,d Idel Endogenous Duodenl low Reltive, protein protein undersupply Men CV e (% o diets ) Lysine Methionine Threonine Isoleuine Leuine Vline Phenyllnine Tryptophn not inluded. Clulted rom requirements or mintenne nd milk prodution see Tle 6. Lrsen et l. (2000). d Results rom 33 dierent diets (Hvelplund, 1986). e Bsed on the duodenl low given in the preeeding olumn. re in % o protein. When this is tken into onsid- (e.g. NIRS) whih re muh more rpid nd n e ertion the vlues given y Rulquin re lower or used on-line during eed prodution, ter pprolysine ut higher or methionine ompred to those prite lirtion nd n utomti set-up. Generlly, in Tle 7. physil nlysis methods my eome relisti These theoretil lultions indite tht dier- lterntives or the diret ut more slow hemil ent mino ids n limit milk prodution nd, methods in routine nlyses o eed qulity. urthermore, they suggest whih mino id is the With more preise knowledge o the nutritionl irst limiting in dierent eeds. The lultions vlue o the tul eed thes it my lso e gree with experiments or estimting the mino id relevnt to onsider doumented smller dierenes requirements or milk prodution o diry ows, nd hnges in the idel protein omposition. These whih hve shown tht dierent mino ids re irst my primrily e used y niml tors, e.g. sex limiting in dierent eeding situtions, nd lso tht nd ge ut lso the helth sttus my e relevnt to lysine nd methionine seem to e the most requently orret or. Future eed evlution or oth ruminnts limiting mino ids (Fisher, 1972; Seymour et l., nd non-ruminnts ims t developing dynmi 1990; Frser et l., 1991; Shw et l., 1992). whole niml models where new knowledge with respet to the idel protein onept n e inorported when ville. 5. Options or uture improvements in the use o idel protein in eed evlution 6. Conlusions Current eed ormultion nd eed evlution is generlly sed on verge tle vlues or the The idel mino id proile is vlule tool or ontents nd digestiility o mino ids in the protein evlution o eeds or rm nimls. The individul eedstus. However, new pprohes or idel protein most investigted is tht or growing nlysis o digestile mino ids sed on rpid in pigs. However, even or this purpose speii vitro nd in situ nlysis tehniques (Hvelplund et mino id proile hs not een inlly doumented l., 1992; Boisen nd Fernndez, 1995) pper to or generlly epted. result in more orret estimtes o the tul eed The idel mino id pttern needs to e relted to thes. Alterntively, physil nlysis methods ville dietry mino ids in the smll intestine,

12 250 S. Boisen et l. / Livestok Prodution Siene 64 (2000) i.e. stndrdized ( true ) digestile mino ids. The Boisen, S., A new protein evlution system or pig eeds opportunity to supply pig diets with industril mino nd its prtil pplition. At Agri. Snd. Set. A, Anim. Si. 48, id preprtions overing the generlly irst limiting Boisen, S., Fernndez, J.A., Predition o the pprent ilel mino ids, i.e. lysine, methionine, threonine nd digestiility o protein nd mino ids in eedstus nd eed tryptophn, hs drwn more ttention to the preise mixtures or pigs y in vitro nlyses. Anim. Feed Si. requirements or the other essentil mino ids, Tehnol. 51, euse they my eome limiting in mino idonentrtions Boisen, S., Beh-Andersen, S., Dnielsen, V., Amino id in sow s milk in reltion to oiil reom- supplemented diets mndtions or mino ids or wenling pigs [in Dnish]. For ruminnts, the determintion o the intestinl Commun. no 712 rom the Ntionl Institute o Animl supply o mino ids, nd onsequently the require- Siene, Denmrk, p. 4. ments or these, is more omplited. Thus, severl Boisen, S., Moughn, P.J., Dietry inluenes on endogenous preditions o the proesses in the digestive trt re ilel protein nd mino id loss in the pig A review. required. These inlude: (i) miroil degrdtion o At Agri. Snd. A, Anim. Si. 46, Boisen, S., Moughn, P.J., Dierent expressions o dietry the dietry protein in the rumen, (ii) miroil net protein nd mino id digestiility in pig eeds nd their synthesis o protein in the rumen relted to the pplition in protein evlution: A theoretil pproh. At speii eed, whih minly orresponds to the Agri. Snd. A, Anim. Si. 46, dietry supply o ermentle rohydrtes, nd (iii) Chung, T.K., Bker, D.H., Idel mino id pttern or digestion in the smll intestine (ilel mino id 10-kilogrm pigs. J. Anim. Si. 70, digestiility) o undegrded dietry protein nd Clrk, J.H., Klusmeyer, T.H., Cmeron, M.R., Miroil protein synthesis nd lows o nitrogen rtions to the miroil protein. duodenum o diry ows. J. Diry Si. 75, More reserh is needed or otining ommonly Cole, D.J.A., Vn Lunen, T.A., Idel mino id ptterns. In: epted nd more orret eed evlution systems, D Mello, J.P.F. (Ed.), Amino Aids In Frm Animl Nutrition, inluding protein evlution systems, or the dier- CAB Interntionl, pp ent rm nimls. The implementtion o suh syso De Lnge, C.F.M., Suer, W.C., Sournt, W.B., The eet protein sttus o the pig on the reovery nd mino id tems, in whih more lexile idel protein onept omposition o endogenous protein in digest olleted rom plys entrl role, n generlly improve eed the distl ileum. J. Anim. Si. 67, utiliztion nd thus redue the vste o nutrients. Fisher, L.J., Response o ltting ows to the intrvenous Furthermore, niml welre nd perormne n e inusion o mino ids. Cn. J. Anim. Si. 52, improved nd environmentl pollution rom exreted Frser, D.L., Ørskov, E.R., Whitelw, F.G., Frnklin, M.R., surplus nitrogen minimized. Limiting mino ids in diry ows given sein s the sole soure o protein. Livest. Prod. Si. 28, Fuller, M.F., Present Knowledge o Amino Aid Requirements For Mintenne nd Prodution: Non-ruminnts. In: Eggum, B.O., Boisen, S., Børsting, C., Dnær, A., Hvelplund, Reerenes T. (Eds.), Protein Metolism nd Nutrition, EAAP pul. no 59, vol. 1, Herning, Denmrk, pp ARC, The Nutrient Requirements o Pigs. Commonwelth Fuller, M.F., Amino id requirements or mintenne, Agriulturl Bureux, Slough, London. ody protein retion nd reprodution in pigs. In: D Mello, Asplund, J.M., The metoli requirement or mino ids J.P.F. (Ed.), Amino Aids in Frm Animl Nutrition, CAB in ruminnts. In: Asplund, J.M. (Ed.), Priniples o Protein Interntionl, pp Nutrition o Ruminnts, CRC Press, London, pp Fuller, M.F., MWillim, R., Wng, T.C., Giles, L.R., The Bergen, W.G., Purser, D.B., Cline, J.H., Eet o rtion on optimum dietry mino id pttern or growing pigs. 2. the nutritive qulity o rumen miroil protein. J. Anim. Si. Requirements or mintenne nd or tissue protein retion. 27, Br. J. Nutr. 62, Boisen, S., New strtegy or optimizing mino id supply Heger, J., Frydryh, Z., Fronek, P., The eet o non to growing pigs. In: Verstegen, M.W.A., den Hrtog, L.A., vn essentil nitrogen on the utiliztion o dietry protein in the Kempen, G.J.M., Metz, J.H.M. (Eds.), Nitrogen Flow in Pig growing rt. J. Anim. Physiol. Anim. Nutr. 57, Prodution nd Environmentl Consequenes, Pudo, Wgen- Hvelplund, T., The inluene o diet on nitrogen nd mino ingen, pp id ontent o mixed rumen teri. At Agri. Snd. 36, Boisen, S., Idel protein nd its suitility to hrterize protein qulity in pig eeds. A review. At Agri. Snd. Set. Hvelplund, T., Hesselholt, M., Digestiility o individul A, Anim. Si. 47, mino ids in rumen miroil protein nd undegrded dietry

13 S. Boisen et l. / Livestok Prodution Siene 64 (2000) protein in the smll intestine o sheep. At Agri. Snd. 37, NRC, Nutrient Requirements o Swine, 10th edition, Ntionl Ademy Press, Wshington D.C., p Hvelplund, T., Mdsen, J., Predition o individul mino Purser, D.B., Buehler, S.M., Amino id omposition o id pssge to the smll intestine o diry ows rom rumen orgnisms. J. Diry Si. 49, hrteristis o the eed. At. Agri. Snd. 39, Rhone Poulen, Rhodimet Nutrition Guide, p. 56. Hvelplund, T., Weisjerg, M.R., Andersen, L.S., Estimtion Rulquin, H., Pisulewski, P.M., Verite, R., Guinrd, J., Milk o the true digestiility o rumen undegrded protein in the prodution nd omposition s untion o postruminl lysine smll intestine o ruminnts y the moile g tehnique. At supply: nutrient-response pproh. Livest. Prod. Si. 37, Agri. Snd., Set. A, Anim.Si. 42, INRA, The Diet o Non-Ruminnt Animls: Pigs, Rits Suer, W.C., Ozimek, L., Digestiility o mino ids in nd Poultry. Institut Ntionl de l Reherhe Agronomique, swine: Results nd their prtil pplitions. A review. Pris, p Livest. Prod. Si. 15, Jørgensen, H., Fernndez, J.A., Beh-Andersen, S., Deposi- Shw, C.G., Bozk, C.K., Whitehouse, N.L., Mesh, M.M.A., tion nd mino id ontents in slughter pigs [in Dnish] Amino id limittion nd low to duodenum t our Commun. no 701 rom the Ntionl Institute o Animl stges o lttion. 1. Sequene o lysine nd methionine Siene, Denmrk, p. 4. limittion. J. Diry Si. 75, Kirhgessner, M., Fikler, J., Roth, F.X., Inluene o Seymour, W.M., Poln, C.E., Herin, J.H., Eet o dietry proline supply on N retention in young growing pigs [in protein degrdility nd sein or mino id inusions on Germn]. J. Anim. Physiol. Anim. Nutr. 73, prodution nd plsm mino ids in diry ows. J. Diry Si. Lrsen, M., Mdsen, T.G., Weisjerg, M.R., Hvelplund, T., 73, Mdsen, J., Endogenous mino id low in the Ski, B., Weisjerg, M.R., Hvelplund, T., Rumen nd totl duodenum o diry ows. At Agri. Snd., Set. A, Anim. intestinl trt digestiility o protein nd mino ids rom Si. (in press). dierent roughges determined in situ. J. Anim. Feed Si. 5, Lenis, N.P., vn Diepen, J.T.M., Shutte, J.B., de Jong, J., The idel pttern o ilel digestile mino ids in diets or Skorko-Sjko, H., Hvelplund, T., Weisjerg, M.R., Rumen growing pigs. In: Verstegen, M.W.A., den Hrtog, L.A., vn degrdtion nd intestinl digestiility o mino ids in Kempen, G.J.M., Metz, J.H.M. (Eds). Nitrogen low in pig dierent roughges estimted y nylon g tehniques. J. prodution nd environmentl onsequenes. EAAP Pul. No. Anim. Feed Si. 3, Pudo, Wgeningen, The Netherlnds, pp Storm, E., Brown, D.S., Ørskov, E.R., The nutritive vlue o Mdsen, J., Hvelplund, T., Weisjerg, M.R., Bertilsson, J., rumen miroorgnism in ruminnts. 3. The digestion o miro- Sprondly, R., Olsson, I., Hrstd, O.M., Volden, H., Tuori, M., il mino nd nulei ids in nd losses o endogenous Vrvikko, T., Huhtnen, R., Olsson, B.L., The AAT/ nitrogen rom the smll intestine o sheep. Br. J. Nutr. 50, PBV protein evlution system or ruminnts. A revision Norwegin J. Agri. Si. suppl. 19, Tuitoek, K., Young, L.G., De Lnge, C.F.M., Kerr, B.J., The Moughn, P.J., Simultion o the dily prtitioning o lysine eet o reduing exess dietry mino ids on growingin the 50 kg liveweight pig A toril pproh to inishing pig perormne: An evlution o the idel protein estimting mino id requirements or growth nd minte- onept. J. Anim. Si. 75, nne. Res. Dev. Agri. 6, Virtnen, A.I., Milk prodution o ows on protein ree Moughn, P.J., Modelling protein metolism in the pig eeds. Siene 153, ritil evlution o simple reerene model. In: Moughn, Wng, T.C., Fuller, M.F., The optimum dietry mino id P.J., Verstegen, M.W.A., Visser-Reyneveld, M.I. (Eds.). Model- pttern or growing pigs. 1. Experiments y mino id ling growth in the pig. EAAP Pul. No. 78. Wgeningen Pers, deletion. Br. J. Nutr. 62, The Netherlnds, pp Wng, T.C., Fuller, M.F., The eet o the plne o Moughn, P.J., Smith, W.C., Cornwell, J.K., Determintion nutrition on the optimum dietry mino id pttern or o the iologil vlue o protein soure with supposedly growing pigs. Anim. Prod. 50, idel mino id lne (A.R.C. 1981) or the young pig (10 Weisjerg, M.R., Hvelplund, T., Hellerg, S., Olsson, S., Snne, to 20 kg liveweight). J. Si. Food Agri. 38, S., Eetive rumen degrdility nd intestinl diges- NRC, Nutrient Requirements o Swine, 9th edition, Ntionl tiility o individul mino ids in dierent onentrtes Ademy Press, Wshington, DC., p. 93. determined in situ. Anim. Feed Si. Tehnol. 62,