Effects of infused methionine, lysine and rumen-protected methionine derivatives on nitrogen retention and wool growth of Merino wethers

Abstract

Nitrogen( N) retentiooa ndw ool growthr ate( WGR)r esponsetso variousa minoa cidsa ndd erivativeas s well as protein sourcesw ered eterminedw ith six ruminallya nd six abomasallyfi stulatedM erino wethersin two balancedc rcss-over designe xperimentsT.h e six treatmentosf the first trial consistedo f a control( RC),r uminallyi nfused:m ethionine(R M), maleylm ethionine(R MM) and2 -methyl-malemyl ethionin(eR MMM),a sw ell aso there ssentiaalm inoa cidss uppliedb y a low (RFM: fish meal)a ndh ighd egradabldei etaryp roteins ource(R SOM:s unflower-oilcakmee al),r espectivelyT.h el atter two treatment(sA FM andA SOM,r espectivelya)n da control( AC) werei ncludedin thes econdtr ial asw ell asa bomasally infusiono f methionine(A M) and/orly sine( AL or AML). Six roughage-basdeide tsw erec ompiledto be iso-nutritiouas nd complementartoy thed ifferente atmentsa ndw eref ed at a maintenanclev el.L ive weightw asn ot affected(P > 0.10)b y anyt reatmenwt hereasth e apparenDt M digestibilityw ase nhance(dP < 0.05)w ith the inclusiono f fish meali n the drets (RFM: 56.'l/o; AFM: 5'7.SVoT)h. e percentagNe retained( 1 5.6a nd3 5.870v s. 26.IEo)d eqeased(P = 0.03)b y ruminally infusedm ethionine(R M) andi ncrease(dP = 0.M) by inclusiono f fish meal( RFM).A bomasallyin fusiono f methionine (AM) resultedin an increase(dP = 0.02)p ercentagNe retained(3 9.0%b) utt hei ntusiono flysine( AL) or both( AML) gave no respons(e2 6.5a nd3 6.64ov s.3}.lVo).WGRw ase nhancebdy 0.21! 0.05 mElcm2lda(yP = 0.0002)a nd0 .27t 0.05m g/ cm'?/da(yP = 0.0001)b y ruminallyin fusiono f derivative(sR MM andR MMM) andt hei nclusiono f naturapl roteins ources (RSOMa ndR FM), respectivelAy.b omasallyin fusiono f methionine(A M) anda mixtureo f aminoa cids( AML) asw ell as dietsc ontainingn aturapl roteins ource(sA SOMa ndA FM) increase(dP < 0.0004)W GR with 31, 35, 19a nd3 8%,r espectively, w hereasly sinei nfusion( AL) hadn o effect.M MM (2-methyl-malemyle thioninea)n df ish meals howg reatp otential as a sourceo f bypassm ethioninee,s peciallyto increasew ool growth( 307oa nd3 6-38Vo)w, hercasM M (maleylm ethionine)(127,)a nds unflower-oilcakmee al( 17-19%)appears to be about half as efficient. 

Stikstof( N)-retensieen wolgroeitemp(oW cTlresponst ot verskeiea minosureen -derivatea sookp roteibnbronnise m ets es ruminale en ses abomasaleg efistuleerdMe erinohamelsin twee gebalanseerdoeo rskakelproefontwerp-eksperimente bepaalD. ie sesb ehandelingvsa nd ie eerstee ksperimenhte tb estaa[u it 'n kontrole( RC),r uminaailn gedruptem; etionien (RM), maleiblmetionie(nR MM) en 2-metielmaleielmetion(ieRnM MM) sowela sa ndere ssensielaem inosurew at onderskeidelikd eur'n laags( RFM:v ismeel)e nh oogsd egradeerbadri€e etproteienbro(RnS OM:s onneblbmoliekoekmeveoro) rsien is. Laasgenoemdtew ee behandelilgs( AFM en ASOM, onderskeidelike)n 'n kontrole (AC) is in die tweede eksperimenint gesluita sooka bomasalien druppelinvga nm etionien(A M) er/of lisien( AL of AML). Sesr uvoergebaseerde di€tei s met inagnemingv and ie verskillendbee handelingosp 'n iso-voedingstofbassaisa mgestelr l teeno nderhoudspeil gevoer.L iggaamsmassias nie deure nigeb ehandelingb eihvloedn ie (P > 0.10) terwyl die skynbarev e.teerbaarheidv an die DM deurd ie insluitingv anv ismee(l RFM:5 6.7%,A FMi 57.57 a)i n die dietev erhoog( P < 0.05)i s. N-retensiea,s p ersentasiev anN ingeneem(1 5.6e n 35.8Vav s.26.17o),1,ste rlaag(P = 0.03)d eurr uminaailn gedruptem etionien(R M) en verhoog( P = 0.04)d eurd iei nsluitingv anv ismeelA. bomasalien druppelinvga nm etionien(A M) hetN -retensiea,s p ersentasie vanN ingeneem(3 9.07o)v,e rhoog( P = 0.02),m aard ie indruppelingva nl isien( AL) of albeia minosure(A ML) het geen respons(2 6.5e n 36.6Vov s.3O.lVog) ehadrt .e.W CT is meto nderskeidel0ik. 21t 0.05m g/cm'z/da(gP = 0.0002)e n 0.27t 0.05m g/cm'?/da(Pg = 0.0001d) eurr uminalein druppelinvga nd ied erivate(R MM enR MMM) end ie insluitingv ann atuurlike proteienbronn(eR SOMe nR FM) verhoogA. bomasalien druppelinvga nm etionien(A M) en 'n mengsevl ana minosure (AML) asookd ietew at natuurlikep roteibnbronn(Ae SOMe nA FM) bevath, etW GT meto nderskeidel3ik1 , 35, 19e t38Vo verhoog( P < 0.0004)t erwyl lisieni ndruppeling(A L) ge€ni nvloedg ehadh et nie.M MM (2-metiel-maleielmetionieenn) vismeelt oon grootp otensiaaal s bron vand eurvloeimetionievn€, ralo m wolgroeit e verhoog( 3O%e n 36-38qa)t,e rsyl maleielmetionie(nM M) (127r)e n sonneblomoliekoekm(e1e7l- 19%)o ngeveedri eh elftes od oeltreff€nwd as.

Keywords: Amino acids, methionine, lysine, derivatives, nitrogen retention, wool growth, i nfusion, sheep.