3.70pp点点通2004

SmallRuminantResearch53(2004)253–273MetabolizableenergyrequirementsoflactatinggoatsI.
V.
Nsahlaia,b,A.
L.
Goetscha,,J.
Luoa,c,Z.
B.
Johnsond,J.
E.
Mooree,T.
Sahlua,C.
L.
Ferrellf,M.
L.
Galyeang,F.
N.
OwenshaE(Kika)delaGarzaInstituteforGoatResearch,LangstonUniversity,P.
O.
Box730,Langston,OK73050,USAbDepartmentofAnimalandPoultryScience,UniversityofNatal,P/BagX01,Scottsville,PMB3209,R.
SouthAfricacCollegeofAnimalScienceandTechnology,NorthwestScience-Technology,UniversityofAgricultureandForestry,Yangling,Shaanxi,712100,ChinadDepartmentofAnimalScience,UniversityofArkansas,Fayetteville,AR72701,USAeDepartmentofAnimalScience,UniversityofFlorida,Gainesville,FL32611,USAfUSMeatAnimalResearchCenter,P.
O.
Box166,ClayCenter,NE68933,USAgDepartmentofAnimalScienceandFoodTechnology,TexasTechUniversity,Box42141,Lubbock,TX79409-2141,USAhPioneerHi-BredInternational,CropGeneticsResearchandDevelopment,7100NW62ndStreet,P.
O.
Box2,Johnston,IA50131,USAReceived24May2002;receivedinrevisedform24April2003;accepted5April2004AbstractDatafrom44studieswith243treatmentmeanobservations,representing2476goatsinvariousstagesoflactation,wereusedtoestimatetherequirementandefciencyofuseofMEformilkproduction.
Developmentandevaluationdatasubsetscomprised,respectively,68and32%ofobservations.
MEintakewasalsoadjustedforenergylostinexcretionofexcessnitrogenouscompoundsinurine(MEExN),as62.
21kJ/gofNintakeaboveendogenousurinaryN(0.
165g/kgBW0.
75).
AdjustedMEintakewaspartitionedintothatusedformaintenanceandactivityinpenorstallsettings(MEm;bytwomethods),MEsecretedinmilkandMEgainedasBW.
ForMethod1,MEm=1.
1*315kJ/kgBW0.
75/km,withkmorefciencyofMEuseformaintenance=0.
503+(0.
019*ME,MJ/kgDM).
ForMethod2,estimatesofMEminacompanionstudyfordairy(501.
3kJ/kgBW0.
75)andothergoatbiotypes(422.
7kJ/kgBW0.
75)wereused.
WhenBWincreased,MEintakewasadjustedfortissueaccretion(efciency=0.
75)toderivedietaryMEusedinmilksecretion(MEl-d).
Milkyieldwascorrectedto4%fat[4%FCM;MJ/kg=1.
4694+(0.
4025*%milkfat)].
FordoesdecreasinginBW,FCMfromthediet(FCMd)wasestimatedbyadjustingforuseofmobilizedtissueenergy(23.
9kJ/g;efciency=0.
84).
NoparticularequationsexplainedconsiderablymorevariabilityinobservedFCMorNEforlactationthanotherequations.
Basedonno-interceptregressions(MEl-dagainstFCMd)withMethod1,thedietaryMErequirementforlactationwas4598(S.
E.
=106.
6)and4937(S.
E.
=106.
5)kJ/kgFCMwithandwithoutadjustmentforMEExN,respectively.
WithMethod2andno-interceptequations,thedietaryMErequirementforlactationwas4882(S.
E.
=105.
2)and5224(S.
E.
=105.
8)kJ/kgFCMwithandwithoutadjustmentforMEExN,respectively.
PredictionaccuracywassimilarbetweenmethodsandimprovedslightlybycorrectionforADG.
Inconclusion,withthelargeamountofdataemployedinthisstudy,theseestimatesandthisfactorialapproachseemusefultopredictenergyrequirementsoflactatinggoats,withpotentialforfutureenhancementsbasedonresearchofthefactorialapproachassumptions.
2004ElsevierB.
V.
Allrightsreserved.
Keywords:Goat;Lactation;EnergyrequirementCorrespondingauthor.
Tel.
:+1-405-466-3836;fax:+1-405-466-3138.
E-mailaddress:goetsch@luresext.
edu(A.
L.
Goetsch).
0921-4488/$–seefrontmatter2004ElsevierB.
V.
Allrightsreserved.
doi:10.
1016/j.
smallrumres.
2004.
04.
007254I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–2731.
IntroductionTheproductivityandlong-termviabilityofanyanimalproductionsystemlargelydependsonqual-ityoftheanimalsandenvironmentalfactors.
Oneofthemostimportantenvironmentalfactorsisthedietbecausefeedscanlimitproductivityintermsofquality,quantityanddistributionwithintheyear.
However,dairyanimalsareoftenintensivelyfarmedandassuchdonotsufferasfrequentlyfromseasonalchangesinfeedsuppliescomparedwithotherclassesoflivestock.
Nonetheless,successfullyprovidingap-propriateamountsandtypesoffeedstointensivelyfarmedlivestocknecessitatessomeknowledgeofnu-trientrequirements.
Moreover,nutrientrequirementsarenotstatic,butcanchangewithgeneticselectionandcrossbreeding.
Furthermore,physiologicalstateoftheanimalinuencesnutrientrequirements.
Con-sequently,livestocknutrientrequirementsmustbeperiodicallyreviewedandreevaluated,thesuccessofwhichisprimarilydictatedbytheavailabilityandqualityofresearchresults.
Becauseoftheimportanceofadequatenutritiontohighlevelsandefcienciesofgoatproduction,thistopichasreceivedanappreciableamountofresearchemphasisinthelast20years.
However,sincethelastNRC(1981)reportforgoats,therehasnotbeenathor-oughcompilingintheUSofdatafromfeedingandnutritionexperimentswithgoatsforuseindescrib-inganimalnutrientrequirements.
Infact,arevisionofnutrientrequirementsforlactatinggoatswassug-gestedbyRandyetal.
(1988)morethan10yearsago,whichinpartmaybebecausetheNRC(1981)MErequirementforlactatinggoatswasbasedonfourex-perimentalvalues.
Therefore,theobjectiveofthisre-searchwastocompileliteraturedataandevaluateMErequirementsoflactatinggoats.
2.
Materialsandmethods2.
1.
DatabaseDatawerecollectedfrompublishedliteratureandassessedforsuitabilityindeterminingnutrientrequire-mentsoflactatinggoats;datameetingprescribedcri-teriawereretained.
Retentionofdatainthedatabasedependedoninformationinthereportconcerningmilkyield(kg),BW(kg),ADG(g/day)andMEintake(kJ/day).
ForstudiesinwhichmeanBWwasnotpre-sented,anaverageofinitialandnalBWwasusedasmeanBW.
IfADGwasprovidedinadditiontoei-therinitialornalBW,thesevaluesandthedurationoftheexperimentwereusedtoestimatemeanBW.
Insomeinstances,fecalandurinecollectionswereper-formed,whichalongwithanassumptionofmethanelossallowedforadirectdeterminationofMEintake.
However,inmostcasesMEintakewasestimatedfromdietaryingredientcompositionandMEconcentrationsinfeedstuffsindietsfromliteraturesources,eitherbyauthorsoftheoriginalreportorcalculatedinthisstudy.
AdetaileddescriptionofhowdietaryMEcon-centrationwasestimatedisinacompanionreport(Luoetal.
,2004b).
Therewere49reportsorreferencesand296treatmentmeanobservationswithestimatesof4%fat-correctedmilk(4%FCM);44ofthesereportsmettheeligibilitycriteria.
Inordertousedatafromfoureligiblestudiesforwhichmilkcompositionwasnotlisted,milkfatcompositionwasestimatedfromtheotherdata.
Becausemilkcompositioncanvarywithbothbreedandstageoflactation,milkcompo-sitionmeanswerecalculatedfordifferentbreedsandphasesoflactation(i.
e.
,earlylactation,weeks1–10;mid-lactation,weeks11–20;latelactation,>weeks20;Table1).
ThesevaluesandmilkyieldwereusedtoestimatemissingFCMdata.
The44eligiblereportscomprised243treat-mentmeanobservationsderivedfrom2476goats.
Thesestudieswererandomlyseparatedintotwosubsets—oneforpredictionequationdevelopmentandtheotherforevaluation.
Thedevelopmentsub-setcomprised34reportswith170treatmentmeanobservationsderivedfrom1605goats(Table2).
2.
2.
DietaryNEsecretedinmilkandFCMarisingfromdietaryNEEnergysecretedinmilk,i.
e.
,NEforlactation(NEl,kJ/day),wascalculatedfrommilkyieldandmilkfatconcentrationwiththeequationofNRC(1989)fordairycattle:NEl(MJ/kg)=1.
4694+(0.
4025*%fatinmilk).
DoestypicallyloseBWduringearlylacta-tion,whichisnormallyrecoupedlater.
ThismeansthatNElcanarisefromenergyofbothfeedandcatabolizedbodytissue.
InordertoestimateNElfromthedietalone(Nel-d),itwasassumedbasedonAFRC(1993,I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273255Table1Summarizedmilkcomposition(mean±standarddeviation)ofgoatsduringdifferentphasesoflactationBreedPhaseanMilkconstituent(%)FatProteinTotalsolidsAlpine1943.
60±1.
9902.
89±0.
51511.
1±2.
492623.
53±1.
1722.
77±0.
58210.
8±0.
063183.
92±2.
0823.
33±0.
677Saanen173.
26±1.
4773.
04±0.
25710.
4±0.
76223.
34±0.
3252.
99±0.
085344.
50±1.
4283.
84±0.
198Nubian144.
23±0.
6192.
59±0.
4398.
3±0.
77244.
38±0.
536Damascus1214.
32±1.
3884.
11±1.
32813.
3±1.
532294.
86±2.
1604.
33±1.
62613.
6±1.
82363.
91±0.
8664.
17±0.
269Granadina115.
943.
1814.
72115.
98±0.
9493.
40±0.
25915.
2±1.
182344.
74±0.
44119.
8±2.
40Angora145.
23±0.
9464.
11±0.
118DwarfeastAfricangoat,Moroccangoat253.
92±1.
1193.
44±1.
53413.
6±2.
55Indigenous/feral1165.
94±3.
1164.
45±1.
03717.
7±1.
09Crossbreed(indigenous*dairy)263.
46±1.
0243.
53±0.
73411.
4±0.
50Otherdairy1153.
99±0.
7732.
99±0.
3652143.
49±0.
8623.
15±0.
282383.
95±0.
4862.
99±0.
142Swedishlandrace2103.
67±0.
5003.
01±0.
33911.
6±0.
75a1:1–10weeks;2:11–20weeks;3:>20weeks.
1998)thatmobilizedtissuecontained23.
9MJ/kgandenergyfrommobilizedtissuewasusedwithanef-ciencyof84%formilksynthesis(NEl-t,kJ/day).
Hence,NEl-dwascalculatedasthedifferencebetweenNElandNEl-t.
Likewise,FCMarisingfromNEl-dalone(FCMd;kg/day)wasestimated.
2.
3.
DietaryMEavailableformilksynthesisArststepinestimatingMEfromthedietusedformilksynthesiswastosubtractthemaintenanceplusactivityrequirement(MEm)fromtotalMEin-take.
Thiswasaccomplishedbytwoapproachesormethods.
ForMethod1,MEmwasderivedwithAFRC(1998)recommendationsfortheNEformaintenancerequirement(NEm;315kJ/kgBW0.
75),energyusedforactivityinapenorstallenvironment(10%ofNEm)andefciencyofMEuseformaintenance[km;0.
503+(0.
019*ME,MJ/kgDM)].
TheaverageMEconcentrationindietsofthedatabasewas10.
5MJ/kgDM(S.
D.
=0.
95;range=7.
1–12.
9),andmeankmwas0.
70(S.
D.
=0.
018;range=0.
64–0.
75).
TheMErequirementforproduction(MEp)wascalculatedbysubtractingMEmfromMEintake.
Method2forestimatingtheMEmrequirementwasbasedonndingsofLuoetal.
(2004b).
Luoetal.
(2004b)estimatedMEmrequirementsforgrow-ingdairyandindigenousgoatsbiotypesof580and489kJ/kgBW0.
75,respectively;theMEmformaturegoatswitharelativelysmalldatabasewas462kJ/kgBW0.
75.
Assumingthatrelativediffer-encesbetweenbiotypesinMEmofgrowinggoatswasmaintainedtomaturity(NRC,2000),maturedairyandindigenousgoatswouldhaveaMEmre-quirementof501.
3and422.
7kJ/kgBW0.
75,respec-256I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273Table2SummaryofthedevelopmentdatasubsetReferenceaSourceForageBreedcLiveweight(kg)ADG(g/day)dFCMerange(kg/day)Typeb%MinMax445Andradeetal.
,1996AH+FS340.
7–43.
780.
030.
01.
10–1.
33428Aguileraetal.
,1990PelletedAH35–40734.
1–40.
649.
378.
71.
40–1.
89751CiszukandLindberg,1988Hay/straw402046.
8–53.
666.
0125.
01.
75–2.
52140Economides,1986AH32–38544.
0–68.
813.
366.
72.
91–4.
31827Fernandezetal.
,1988CSH38–43142.
1–62.
63.
3114.
31.
23–2.
33605Goetschetal.
,2000CSHandAH40–80135.
8–59.
215.
893.
01.
62–3.
5353Hadjipanayiotou,1992BH22–24565.
2–65.
911.
414.
32.
42–2.
92231Hadjipanayiotou,1984BS(urea-treated)14–17563.
0–63.
12.
05.
01.
75–1.
80233Hadjipanayiotou,1987BH24–30552.
0–61.
045.
53.
12.
29–2.
84320Hadjipanayiotou,1988bBH12–14561.
7–62.
611.
026.
01.
87–2.
21293Hadjipanayiotou,199550BH:50BS30573.
2–73.
351.
975.
02.
67–2.
78241Hadjipanayiotouetal.
,198865BH:35AH30566.
8–68.
026.
871.
43.
98–3.
99374HadjipanayiotouandPhotiou,199518BH:27BS562.
7–67.
5202.
0156.
01.
55–1.
79296Hadjipanayiotouetal.
,199616BS:56BH25571.
2–74.
1199.
047.
02.
58–3.
72367Hongetal.
,1988AH59–69268.
9130.
0100.
03.
30–3.
70533Hussainetal.
,1996Hayandsilage20–231944.
0–45.
426.
2183.
30.
72–0.
95298Kawasetal.
,1991Cunhasilage45–751436.
6–37.
150.
0120.
00.
43–0.
49349Kiranadietal.
,1994GrassandGS48–60122032.
6372.
40.
08–0.
21253LoucaandPapas,1973AH26556.
3–61.
050.
077.
42.
27–2.
60258Luetal.
,1990aAMandCSH40–45148.
68.
024.
02.
01–2.
31300Luetal.
,1990bCSH33–37147.
831.
051.
02.
69–2.
72343Lu,1993CSH29–36147.
45.
724.
82.
42–2.
4390Qietal.
,1992BG+GPH43165.
336.
420.
82.
65–2.
81337Randyetal.
,1988GH51.
6–61.
6192.
0229.
32.
23–4.
00842Rapettietal.
,2001Grasssilage55247.
0–61.
529.
0125.
01.
89–4.
3796Sahluetal.
,1993AM5157.
6–63.
429.
62.
03.
32–3.
96828Sahluetal.
,1999AH+BG22–38843.
0–44.
334.
961.
80.
69–1.
06341Santinietal.
,1991AH37–82160.
0–62.
07.
1100.
04.
28–5.
4694Santinietal.
,1992AH37–82162.
0–65.
080.
040.
03.
30–3.
50657SanzSampelayoetal.
,1998AH(long/pelleted)44–49749.
1–49.
767.
433.
71.
80–1.
83350Sastradipradjaetal.
,1994Grass25–391221.
568.
019.
00.
28–0.
55726Schiavonetal.
,1996GH20151.
423.
023.
01.
49412Sibandaetal.
,1997GHandAH1235.
1–41.
09.
059.
00.
75–1.
31342Tehetal.
,1994CSH19–20148.
2–54.
839.
6110.
34.
22–4.
58aDatabasereferencenumber.
bAH:alfalfahay;FS:foragesorghum;CSH:cottonseedhulls;BH:barleyhay;BS:barleystraw;GS:grasssilage;AM:alfalfameal;BG:bermudagrass;GPH:groundpeanuthulls;GH:grasshay;listednumbersarepercentagesofDM.
c1:Alpine;2:Saanen;3:Nubian;5:Damascus;7:Granadina;8:Angora;12:indigenousferal;14:crossbred(indigenous*dairytype);19:otherdairy;20:Swedishlandrace.
dMin:minimum;max:maximum.
eFCM:4%fat-correctedmilk.
tively.
AnadjustmentofMEmforthestateoflac-tation(comparedwithnonlactinganimals)ofNRC(2000)(i.
e.
,20%greater)wastestedbutfoundtoleadtopoorrelationshipscomparedwiththosederivedwithoutadjustment.
InadditiontousingMEintakeaboveMEmformilkproduction,MEcanbeusedfortissueaccretion,ex-cretionandbergrowth.
Consequently,fordoesin-creasinginBW,theAFRC(1993)recommendationfortheenergyconcentrationintissuegain(23.
9MJ/kg)andtheNRC(1989)recommendationforefciencyofuseofdietaryMEintissuedeposition(kg=0.
75)bylactatingdairycattlewereemployedtocalculateMEusedforgain(MEg)andaccretedenergy(NEg).
MEgI.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273257wassubtractedfromMEptoestimatetheremainingamountofMEfromthedietavailableformilksyn-thesis(MEl-d).
MetabolizabilityofenergyinfeedstuffsistypicallydeterminedatornearthemaintenancelevelofnutrientintakeandatornearNequilibrium,thepointatwhichNintakeandexcretionareequal.
However,inordertomeetproductionneeds,goatsoftenconsumeNinex-cessoftheequilibriumpoint,resultinginconsiderableexcretionofurinaryN,principallyasurea.
EnergyinurinaryNaboveendogenousurinaryN(EUN)con-ceivablycouldbeusedinotherproductivefunctions.
GiventheverywiderangeinCPconcentrationinthedatabase(i.
e.
,9.
9–19.
9%),anapproachsimilartothatofTyrrelletal.
(1970)wasusedtoderivetheenergycostofexcretionofexcessN.
TheEUNestimateof0.
165g/kgBW0.
75forgoatsproposedbyLuoetal.
(2004a)wasapplied.
UrinaryNaboveEUNwasassumedtobeexcessurinaryN(ExUN,g/day).
However,therewereonly81treat-mentmeanobservationsinwhichurinaryNoutputwaslisted,includingonesfromfourreports(ManikandSastradipradja,1989;Baracosetal.
,1991;AndrighettoandBailoni,1994;Brun-Bellut,1997)thatdidnotmeetselectioncriteriaforuseinestimat-ingtheMErequirementforlactation.
ThedietaryCPconcentrationrangedfrom36to214g/kgDM.
ItisexpectedthatforagivendietaryCPconcentration,urinaryNoutputincreaseswithincreasingmaturityandthusBWoftheanimal.
ThispatternofvariationinurinaryNintheoryshouldvarywithdietaryCPconcentration,resultinginafamilyofcurves.
Giventhatthebehaviorofthisrelationshipwasnotknown,bothmultipleregressionandnon-linearregressionproceduresweretested;thelatteraccountedfor13%morevariationthantheformer.
Thus,anon-linearregressionofExUNondietaryCPconcentration(%)andBWwasttedandusedtoderiveExUNforobservationswhereurinaryNwasnotlisted:ExUN=0.
555(S.
E.
=0.
1401)*BW0.
048(SE=0.
0037)*CP,n=81,R2=0.
72(1)NinetreatmentmeanobservationsfromthedatabasehadestimatesofbothurinaryNandenergy.
Aregres-sionofurinaryenergyagainstN(n=9;adjusted-R2=0.
95)indicatedthattheenergycontentofurinewas33.
01(S.
E.
=0.
943)kJ/gofurinaryN;thisisverysimilartoavalueof34usedbyKatipanaandSastradipradja(1994)andAstutietal.
(1998).
Moreover,Emmans(1994)estimatedthat29.
2kJofheatenergyisreleasedpergramofurinaryN.
Thus,62.
21kJ/gofNwasmultipliedbyExUNtoestimateMElostinExUN(MEExN,kJ/day).
MEExNwassub-tractedfromMEl-dtoderiveavalueadjustedforlossofenergywithexcretionofexcessN.
2.
4.
EfciencyofuseoftotalanddietaryMEpandMEmplusMEpWithbothmethods,NEforproduction[NEp=NElplusdepositedtissueenergy(NEg)]wasregressedagainstMEptoestimateefciencyofuseofMEp(kp).
Similarly,efciency(kp-d)ofuseofdietaryMEforproduction(MEp-d)wasderivedbyregressingNEpfromthediet(NEp-d=NEl-d+NEg)againstMep-d.
Also,NEformaintenanceplusproduction(NEmp=NEm+NEp)wasregressedagainsttotalMEmplusMEp(MEmp)andMEmplusdietaryMEforproduc-tion(MEmp-d)toobtaincombinedefcienciesforpro-duction(kmpandkmp-d,respectively).
kp-dandkmp-dwerederivedusingdataofanimalsthatwerenotlos-ingBW,andefciencieswereestimatedwithoutandwithadjustingforMEExN.
Becauseoverone-halfofthedatawasderivedfromgenotypesofgoatsselectedformilkproduction,dummyvariableswereusedtotestforthispotentialeffect[Bdummy=1fordairygoatbiotypesand0forothers;Sdummy=productofavailableenergyinput(i.
e.
,independentvariable;MEp,MEp-d,MEmporMEmp-d)andBdummy].
2.
5.
StatisticalanalysesAllanalysesanddataderivationstepswereper-formedwithSAS(1990).
Regressionswerenotweightedbythenumberofobservationspertreatmentmean.
MEl-d(kJ/day)wasregressedagainstFCMdtoestimatedietaryenergyrequiredtosynthesize1kgofFCM.
TheefciencywithwhichMEl-dwasusedformilksynthesis(kl-d)wasderivedbyregressingNEl-d(kJ/day)againstMEl-d(kJ/day),andalsoindirectlybyregressingMEl-dagainstNEl-d.
Regressionsweret-tedforMEl-dandNEl-dbothwithandwithoutadjust-mentforMEExN.
Modelswithandwithoutinterceptswereimplementedbecauseinprincipleintercepts258I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273shouldbezero.
Toimprovemodelt,observationsforwhichthemagnitudeoftheresidualsexceededtwotimestherootmeansquareerror(R.
M.
S.
E.
)wereomittedfromanalyses,andregressionswereretted.
BasedonthepatternofscatterplotsofresidualsofMEl-dandNEl-dandpresenceofsomepositiveintercepts,asnotedbelow,afurtherinvestigationen-taileduseofmultipleregressionsofMEintake(kJ/kgBW0.
75)againstADG(g/kgBW0.
75),FCM(kg/kgBW0.
75)and(or)NEl(kJ/kgBW0.
75).
Equationsderivedfromthedevelopmentdatasubsetwereusedtopredictvaluesfortheevaluationdatasubset.
Observedvalueswereregressedonpredictionstodeterminewhetherinterceptsandslopesequaledzeroandone,respectively(MontgomeryandPeck,1982);anequationwithaninterceptofzeroandslopeofoneindicatesgoodt.
Fig.
1.
Relationshipswiththedevelopmentdatasubsetbetween4%fat-correctedmilk(FCMd;kg/day)fromthedietanddietaryMEforlactation(MEl-d;MJ/day),andbetweendietaryNEforlactation(NEl-d;MJ/day)andMEl-d(MJ/day)without(A,C)andwith(B,D)correctionforenergylostinexcretionofexcessN,respectively.
BasedonMethod1,withuseofassumptionsofAFRC(1998)topredictMEformaintenanceandactivity.
3.
Results3.
1.
MEl-d/FCMdandkl-dwithMethod1Fig.
1depictsrelationshipsbetweenMEl-dandFCMdandNEl-dforthedevelopmentdatasubsetbasedonMethod1.
Eqs.
(2)and(3)(Table3)wereobtainedbyregressingMEl-d(kJ/day)againstFCMd(kg/day)afteradjustingforMEExNandwithoutad-justment,respectively.
Interceptsforbothequationsdidnotdiffer(P>0.
05)fromzero.
Whenregressionswereforcedtopassthroughtheorigin,differing(P0.
05)slopeswere0.
62(S.
E.
=0.
014)and0.
58(S.
E.
=0.
013)withandwithoutadjustingforMEExN,re-spectively.
EfciencyofdietaryMEuseforlactationcanalsobederivedbydividingtheenergyconcentra-tioninFCM(3.
079MJ/kg)byslopesofno-interceptequationsofEq.
(2)and(3)(e.
g.
,NRC,1989),result-inginkl-dof0.
67and0.
62withandwithoutadjustingforMEExN,respectively.
SimilartotheapproachusedforEqs.
(2)and(3),MEl-dwasregressedagainstNEl-d,resultinginEq.
(6)withadjustmentforMEExNandEq.
(7)withoutad-justment(Table3).
Interceptsofbothequationsdidnotdiffer(P>0.
05)fromzero,incontrasttointerceptsofEqs.
(4)and(5).
Forcingtheseregressionthroughtheoriginyieldeddiffering(P>0.
05)regressioncoef-cientsof1.
49(S.
E.
=0.
035)and1.
60(S.
E.
=0.
035)withandwithoutadjustingforMEExN,correspond-ingtokl-dof0.
67and0.
63,respectively,asexpectedbasedoncalculationbydivisionofenergyinFCMbyslopesofno-interceptequationsofEqs.
(2)and(3).
Plotsofresiduals(observed–predictedversuspre-dicted)ofMEl-dandNEl-dforEqs.
(2)–(5)wereestab-lishedwiththedevelopmentdatasubset;theseshowednoobviousbiasinprediction.
ResidualsofMEl-dandNEl-dforno-interceptequationswereplotted,againwithnoobviousbiasnoted.
Also,plotsofresidualsofMEl-dfromno-interceptandinterceptregressionsofMEl-dagainstNEl-ddidnotdisplayobviouspatternsofchangeasobservedNEl-dincreased.
However,itwasnotedthattheratioofobserved:predictedvaluesinthedevelopmentdatasubsetforEqs.
(2)–(7)tendedtovarywithADG.
Hence,ratioswereregressedagainstADG(g/day)toderivemultiplicativecorrectionfac-tors(CF1)reportedinTable4.
3.
2.
MEl-d/FCMdandkl-dusingMEmwithMethod2Fig.
2depictsrelationshipsbetweenMEl-dandFCMdandNEl-dforthedevelopmentdatasubsetbasedonMethod2.
Eqs.
(8)and(9)(Table3)wereobtainedbyregressingMEl-d(kJ/day)againstFCMd(kg/day)afteradjustingforMEExNandwithoutad-justment,respectively.
InterceptsforbothEquationsdidnotdiffer(P>0.
05)fromzero.
Whenregressions260I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273Table4CorrectionfactorsforADGtopredict4%fat-correctedmilkyield(CF1)andtotalNEoflactation(CF2)basedonno-interceptversionsofEqs.
(2)–(13)EquationDependentvariableIndependentvariableaEstimatebR.
M.
S.
E.
cAdjusted-R2AdjustedforexcessNdInterceptSlopeMethod1e2CF1ADG1.
077(0.
0293)0.
0017(0.
00037)0.
360.
11Yes3CF1ADG1.
076(0.
0306)0.
0018(0.
00033)0.
380.
11No4CF1ADG1.
158(0.
0312)0.
0019(0.
00039)0.
380.
13Yes5CF1ADG1.
151(0.
0000)0.
0020(0.
00000)0.
400.
13No6CF1ADG1.
077(0.
0293)0.
0017(0.
00037)0.
360.
11Yes7CF1ADG1.
076(0.
0306)0.
0018(0.
00038)0.
380.
11NoMethod2e8CF2ADG1.
059(0.
0296)0.
0018(0.
00037)0.
370.
12Yes9CF2ADG1.
034(0.
0270)0.
0016(0.
00034)0.
330.
11No10CF2ADG1.
132(0.
0316)0.
0020(0.
00040)0.
390.
13Yes11CF2ADG1.
098(0.
0290)0.
0018(0.
00036)0.
350.
13No12CF2ADG1.
034(0.
0230)0.
0016(0.
00034)0.
330.
11Yes13CF2ADG1.
059(0.
0296)0.
0018(0.
00037)0.
370.
12NoaADGisliveweightgain(g/day).
bValuesinparenthesesareS.
E.
cRootmeansquareerror.
dYes:adjustedforexcretionofexcessurinaryN;No:noadjustment.
eMethod1:useofassumptionsofAFRC(1998)topredictMEformaintenanceandactivity;Method2:useofestimatesofMEformaintenanceandactivityfromLuoetal.
(2004b).
wereforcedtopassthroughtheorigin,differing(P>0.
05)slopeswere4882(S.
E.
=105.
2)and5224(S.
E.
=105.
8)kJ/kgBW0.
75withandwithoutadjustingforExUN,respectively.
TheefciencyofutilizationofMEl-dforlactationwasrstderivedbyregressingNEl-d(kJ/day)againstMEl-d(kg/day);thisresultedinEq.
(10)(afteradjust-ingforMEExN)andinEq.
(11)(withoutadjustmentforMEExN;Table3).
InterceptsforbothEqs.
(10)and(11)weredifferentfromzero(P0.
05)slopeswere0.
59(S.
E.
=0.
013)and0.
55(S.
E.
=0.
011)withandwithoutadjustingforMEExN,respectively.
EfciencyofdietaryMEuseforlacta-tionwasalsoderivedbydividingtheenergyconcen-trationinFCMbyslopesofno-interceptequationsofEqs.
(8)and(9)(e.
g.
,NRC,1989),resultinginkl-dof0.
63and0.
59withandwithoutadjustingforMEExN,respectively.
SimilartotheapproachusedforEqs.
(6)and(7),MEl-dwasregressedagainstNEl-d,resultinginEq.
(12)withadjustmentforMEExNandEq.
(13)withoutadjustment(Table3).
InterceptsforbothEqs.
(12)and(13)didnotdiffer(P>0.
05)fromzero,incontrasttointerceptsofEqs.
(10)and(11).
Forcingtheseregressionthroughtheoriginyieldeddiffer-ing(P>0.
05)regressioncoefcientsof1.
59(S.
E.
=0.
034)and1.
70(S.
E.
=0.
034)withandwithoutadjustingforMEExN,correspondingtokl-dof0.
63and0.
59,respectively,asexpectedbasedoncalcu-lationbydivisionofenergyinFCMbyslopesofno-interceptequationsofEqs.
(8)and(9).
PlotsofresidualswereexaminedasforequationsofMethod1,withnoobviousbiasdetected.
Itwasobservedwiththedevelopmentdatasubset,asforMethod1,thatbasedonno-interceptmodelstheratioofobserved:predictedFCMandNEltendedtochangewithincreasingADG.
Consequently,theseratioswereregressedagainstADG(g/day)toderivemultiplica-tivecorrectionfactors(CF2;Table4).
3.
3.
PredictionsfortheevaluationdatasubsetTheno-interceptequations(Eqs.
(2)–(13);Table3)andtheircorrespondingcorrectionfactors(Table4)wereusedtopredictFCMandNEl(P-FCMandI.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273261Fig.
2.
Relationshipswiththedevelopmentdatasubsetbetween4%fat-correctedmilk(FCMd;kg/day)fromthedietanddietaryMEforlactation(MEl-d;MJ/day),andbetweendietaryNEforlactation(NEl-d;MJ/day)andMEl-d(MJ/day)without(A,C)andwith(B,D)correctionforenergylostinexcretionofexcessN,respectively.
BasedonMethod2,withuseofestimatesofMEformaintenanceandactivityfromLuoetal.
(2004b).
P-NEl,respectively)intheevaluationdatasubset,consistingof81observations.
Regressionsofob-servedagainstpredictedvaluesresultedinequationsreportedinTable5,andmeansofpredictedandob-servedvaluesforthereportsintheevaluationdatasubsetaregiveninTables6and7forFCMandNEl,respectively.
Interceptsandslopesdidnotdifferfromzeroandone,respectively(P>0.
05),exceptthatforEq.
(6)theslopewaslessthanone(P0.
05)foranyefciency.
Ratiosofobserved–predictedNEtendedtochangewithincreas-ingADG.
Consequently,theseratioswereregressedagainstADG(g/day)toderivemultiplicativecorrec-tionfactors(CF3)reportedinTable9.
ObservedMEp,MEp-d,MEmpandMEmpintheevaluationdatasubsetwereregressedagainstpredic-tionsbasedonno-interceptversionsofEqs.
(14)–(29)andCF3;forbothmethodsinterceptsandslopesdidnotdifferfrom0and1,respectively(P>0.
05),andexplainedvariabilitywassimilarbetweenmethodsaswell(Table10).
AdjustmentforMEExNdidnotim-provepredictions.
Table11providesobservedandpre-dictedvaluesforreportsintheevaluationdatasubset.
3.
5.
RegressionrelationshipsamongvariablesEstimatesofklandME/FCM(kJ/kg)basedonmul-tipleregressionanalysiswere,respectively,0.
70and4384(Table12;Eqs.
(30)and(31))withoutcorrectingforMEExN,and0.
72and4298(Table12;Eqs.
(32)and(33))afteradjustingforMEExN.
Usingtheevaluationdatasubset,predictionpotentialofEqs.
(30)–(33)wasalsoassessed(Table13);slopesdidnotdifferfromonebutinterceptsdifferedfromzero(P20weeks.
eValueswerepredictedfromtheno-interceptequations.
fPredictedobserved.
264I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273Table7ObservedversuspredictedNEoflactation(NEl,MJ/day)fortheevaluationdatasubsetbasedontheefciencyofuseforlactationofdietaryME(kl-d)fromno-interceptversionsofEqs.
(4)(P4),(5)(P5),(6)(P6),(7)(P7),(10)(P10),(11)(P11),(12)(P12)and(13)(P13)andADGcorrectionfactorsReferenceaSourceForageObservedNElPredictedNElTypeb%P4,kl-d=0.
62P5,kl-d=0.
58P6,kl-d=0.
67P7,kl-d=0.
63P10,kl-d=0.
59P11,kl-d=0.
55P12,kl-d=0.
63P13,kl-d=0.
59788Abijaoudeetal.
,2000AH+SBP654.
624.
815.
766.
235.
645.
086.
394.
986.
26133Badamanaetal.
,1990Hay57–618.
136.
166.
456.
736.
366.
066.
795.
966.
69292Brun-Bellutetal.
,1990Driedbeetpulp10–157.
336.
528.
258.
518.
087.
148.
247.
008.
07292Brun-Bellutetal.
,1990Driedbeetpulp10–156.
185.
866.
716.
986.
605.
736.
555.
646.
45495Eik,1991Grasssilage6.
986.
756.
546.
926.
455.
756.
525.
666.
43485El-Galladetal.
,1988Berseem,cloverhay,sweetsorghum20–402.
123.
944.
214.
494.
154.
164.
864.
104.
79739Goetschetal.
,2001CottonseedhullsandgroundAH35–8010.
2110.
419.
6610.
279.
568.
9510.
078.
849.
97234Hadjipanayiotou,1988aBarleystrawandBH245.
916.
116.
687.
076.
585.
626.
615.
536.
50153HadjipanayiotouandHadjidemetriou,1990BH25–655.
445.
535.
185.
515.
084.
735.
444.
635.
34735Luetal.
,1987Cottonseedhulls8.
257.
409.
279.
399.
098.
679.
588.
509.
39842Rapettietal.
,2001Grasssilage5513.
2611.
7015.
2015.
8014.
8513.
1315.
5412.
8515.
18842Rapettietal.
,2001Grasssilage5510.
7211.
8815.
3816.
0415.
0213.
1215.
6412.
8315.
29842Rapettietal.
,2001Grasssilage557.
058.
018.
959.
688.
807.
399.
167.
269.
01707Schmidelyetal.
,2002PelletedAHandSBPsilage7014.
588.
8111.
2211.
7110.
979.
7011.
519.
4911.
26707Schmidelyetal.
,2002PelletedAHandSBPsilage7013.
6513.
1313.
4614.
2113.
3012.
0913.
7711.
9313.
60707Schmidelyetal.
,2002PelletedAHandSBPsilage7012.
0211.
0313.
3613.
9313.
1011.
7913.
7311.
5613.
47Meandifference(Pred-Obs)c0.
520.
611.
060.
450.
460.
870.
610.
70aDatabasereferencenumber.
bAH:alfalfahay;BH:barleyhay;SBP:sugarbeetpulp.
cPredictedobserved.
I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273265Table8RelationshipsbetweenNE(kJ/day)andME(kJ/day)forproductionand(or)maintenanceaEquationDependentvariablebIndependentvariablecEstimatedR.
M.
S.
E.
eAdjusted-R2kporkmpfInterceptSlopeMethod1g14NEpMEp2134(428.
7)0.
48(0.
031)2069.
20.
580.
62(0.
012)15MEp-n2373(421.
5)0.
49(0.
033)2091.
50.
570.
66(0.
014)16NEmpMEmp2959(623.
3)0.
53(0.
027)2105.
00.
700.
66(0.
008)17MEmp-n3105(625.
5)0.
55(0.
028)2127.
30.
700.
68(0.
008)18NEp-dMEp-d1452(553.
6)0.
58(0.
042)2001.
00.
630.
68(0.
015)19MEp-d-n1736(546.
5)0.
59(0.
044)2031.
50.
620.
72(0.
016)20NEmp-dMEmp-d1550(812.
9)0.
62(0.
037)2020.
60.
720.
69(0.
009)21MEmp-d-n1691(821.
1)0.
64(0.
039)2050.
50.
720.
72(0.
009)Method2g22NEpMEp1865(408.
2)0.
50(0.
031)2041.
20.
600.
63(0.
012)23MEp-n2106(402.
5)0.
51(0.
032)2067.
30.
600.
66(0.
013)24NEmpMEmp2344(574.
2)0.
56(0.
025)2094.
50.
740.
66(0.
007)25MEmp-n2487(577.
5)0.
58(0.
026)2120.
70.
740.
69(0.
008)26NEp-dMEp-d1244(542.
6)0.
59(0.
042)2001.
20.
640.
68(0.
015)27MEp-d-n1542(537.
7)0.
61(0.
044)2038.
90.
630.
73(0.
016)28NEmp-dMEmp-d1038(769.
6)0.
64(0.
035)2037.
90.
760.
70(0.
009)29MEmp-d-n1181(779.
7)0.
59(0.
037)2073.
90.
750.
72(0.
009)aMEp:MEavailableforproduction;MEp-d:MEpfromthediet;MEmp:MEformaintenanceplusMEp;MEmp-d:MEmpfromthediet.
bNEp:NEforproduction;NEp-d:NEpfromthediet;NEmp:NEformaintenanceplusNEp;NEmp-d:NEmpfromthediet.
cMEp-n,MEp-d-n,MEmp-nandMEmp-d-nare,respectively,MEp,MEp-d,MEmpandMEmp-dadjustedforMElostinexcretionofexcessurinaryN.
dValuesinparenthesesareS.
E.
eRootmeansquareerror.
fkpandkmpareslopesofno-interceptmodels,indicatingefciencyofuseofMEpandMEmp,respectively.
gMethod1:useofassumptionsofAFRC(1998)topredictMEformaintenanceandactivity;Method2:useofestimatesofMEformaintenanceandactivityfromLuoetal.
(2004b).
1981),whereaspositiveproteinretentioncancoex-istwithnegativeenergybalance(Haqueetal.
,1988).
Anyover-valuationoftheenergyvalueofBWchange,whichisquitepossibleasdiscussedbelow,wouldcon-tributetopositiveinterceptswhenNEl-dwasregressedagainstMEl-d.
TheenergyconcentrationinliveweightchangefromEqs.
(30)–(33)of11.
3MJME/kgADGislessthanone-halfoftheassumedAFRC(1998)valueof23.
9MJ/kg,butnonethelessmaybephysiolog-icallyfeasible.
Forexample,ADGisleastcostly(e.
g.
,15.
1kJ/gADG)iftissueaccretedismainlyleanconsistingof75%water,particularlyifpartofthedepositioncostisfueledbymobilizedtissueenergy.
However,asalludedtolaterregardingtheestimateofkl,coefcientsinmultipleregressionshavebio-logicalrelevanceinthecontextofuseintheentireequationandnotnecessarilywhenviewedalone.
Tomoreaccuratelydescribenutrientrequirementsformilkproductionbygoats,agreaterknowledgeofthecompositionofliveweightlossandgainthrough-outlactationisneeded(AFRC,1998;SuttonandAlderman,2000).
Theassumptionofaconstantenergyconcentrationinliveweightchangemayhavecon-tributedtochangeintheratioofobserved:predictedenergyneedsofthedevelopmentdatasubsetwithincreasingADG,necessitatinguseofcorrectionfactors.
4.
1.
2.
GenotypeInformationavailableinthedatabasedidnotpermitanestimationofenergyexpendedforthesynthesisofber,whichcouldhavevariedamonggenotypes.
Also,withMethod1itwasassumedthatMEmwasthesameforallgoatsrelativetoBW0.
75andthatMEwasnotinuencedbylevelofmilkproduction.
However,266I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273Table9Correctionfactors(CF3)forpredictionofMEforproductionand(or)maintenancebasedonno-interceptversionsofEqs.
(14)–(29)EquationDependentvariableIndependentvariableaEstimatebR.
M.
S.
E.
bAdjusted-R2InterceptSlopeMethod1c14CF3ADG0.
951(0.
0293)0.
0007(0.
00022)0.
790.
0515CF3ADG0.
936(0.
0203)0.
0003(0.
00022)0.
270.
0116CF3ADG1.
010(0.
0101)0.
0008(0.
00011)0.
130.
2217CF3ADG1.
008(0.
0099)0.
0008(0.
00011)0.
130.
2218CF3ADG1.
136(0.
0297)0.
0018(0.
00033)0.
210.
2119CF3ADG1.
118(0.
0295)0.
0017(0.
00032)0.
210.
1920CF3ADG1.
081(0.
0160)0.
0011(0.
00017)0.
110.
2721CF3ADG1.
077(0.
0160)0.
0011(0.
00017)0.
110.
25Method2c22CF3ADG0.
949(0.
0209)0.
0006(0.
00023)0.
840.
0323CF3ADG0.
935(0.
0220)0.
0002(0.
00024)0.
280.
0024CF3ADG1.
008(0.
0106)0.
0007(0.
00012)0.
130.
1925CF3ADG1.
007(0.
0105)0.
0007(0.
00012)0.
130.
1826CF3ADG1.
143(0.
0342)0.
0018(0.
00038)0.
250.
1627CF3ADG1.
125(0.
0336)0.
0016(0.
00037)0.
240.
1428CF3ADG1.
084(0.
0173)0.
0011(0.
00019)0.
120.
2329CF3ADG1.
081(0.
0173)0.
0011(0.
00017)0.
120.
21aADGisliveweightgain(g/day).
bRootmeansquareerror.
cMethod1:useofassumptionsofAFRC(1998)topredictMEformaintenanceandactivity;Method2:useofestimatesofMEformaintenanceandactivityfromLuoetal.
(2004b).
activityandmetabolicratesmaydifferamongbreedsandatdifferentratesofmilkproduction.
4.
1.
3.
MEmSlopesofregressionsforcedtopassthroughtheoriginwereemployedbecausetheoreticallyinterceptsshouldnotdifferfromzero.
Also,forbothMEl-dandkl-d,theslope,nottheintercept,isofinterest.
ItcannotbeconclusivelydiscernedwhyinterceptsofEqs.
(4),(5),(10)and(11)differedfromzero.
However,oneplausibleexplanationinvolvesassump-tionsofMEm.
Theseequationsaddresstheincreaseinenergyrequiredforeachunitincreaseinmilkpro-ducedaswellasanaccompanyingcostofmaintain-ingmammaryglandtissue.
ItisassumedthatthelatterchangeislinearwithincreasingMEl-d,asisalsopresumedformilkproduction.
However,sincealltreatmentmeanobservationswereforlactatingan-imals,itispossiblethatthepredictionofMEl-datzeromilkproductionincludesenergyattributabletomaintainingafunctionalmammaryglandcapableofmilksecretion.
Inaddition,differentstagesofpreg-nancycouldimpactenergyrequirementsoflactatinganimals.
Datausedinthisstudywerederivedfromexper-imentswithanimalsatvariousstagesoflactationandgeographicallocations.
Animalsacclimatedtoenvironmentswithhightemperatureshavelowermaintenancerequirementsthanonesrearedwithlowertemperatures(Tolkampetal.
,1994;NRC,2000).
Regardingstageoflactation,slightlymorethanone-halfoftheanimalswereintheearlyphaseoflactation,whenbodyenergyreservesareoftenmobilized.
Eik(1991)observedthatbodyfatindoesdecreaseduntilthe28thweekoflactation.
Inearlylac-tation,itiscommonforlactatingdoestohavepositiveproteinretentionbutnegativeenergybalance(Haqueetal.
,1988;Aguileraetal.
,1990;Prietoetal.
,1990;Sastradipradjaetal.
,1994),whichcanbeexplainedbyfatmobilizationandarelativelyhighandincreasingproportionoflean(protein)tissueinthebody.
Hence,becauseofmoreenergyrequiredtomaintainproteinthanfat(Webster,1980),relativetoBW0.
75themain-tenanceenergyrequirementmaybehigherinearlyI.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273267Table10RegressionsofobservedagainstpredictedME(P-ME;kJ/day)withtheevaluationdatasubsetforproductionand(or)maintenancebasedonno-interceptversionsofEqs.
(14)–(29)andADGcorrectionfactorsEquationInterceptP-MER.
M.
S.
E.
aAdjusted-R2Signicance(P20weeks.
dObs:observed;Pred:predicted;Pred-N:predictedwithanadjustmentforenergylostinexcretionofexcessurinaryN.
eMethod1:useofassumptionsofAFRC(1998)topredictMEformaintenanceandactivity;Method2:useofestimatesofMEformaintenanceandactivityfromLuoetal.
(2004b).
fPredictedMEp-dandMEmparenotshownbecauseofBWloss.
gPredictedobserved.
I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273269Table12RegressionsofMEintake(kJ/kgBW0.
75)againstADG(g/kgBW0.
75),4%fat-correctedmilk(FCM;kg/kgBW0.
75)andNEoflactation(NEl,kJ/kgBW0.
75)EquationInterceptADGFCMNElR.
M.
S.
E.
aAdjusted-R2klbEstimateS.
E.
EstimateS.
E.
EstimateS.
E.
EstimateS.
E.
WithoutadjustingforenergylostinexcretionofexcessurinaryN3058328.
611.
32.
204384222.
0439.
60.
693158328.
611.
32.
201.
420.
072439.
70.
690.
70AfteradjustingforenergylostinexcretionofexcessurinaryN3257428.
511.
32.
204298221.
3438.
40.
693357428.
511.
32.
191.
390.
071438.
30.
690.
72aRootmeansquareerror.
bEfciencyofMEuseforlactation.
Table13Regressionsofobservedagainstpredicted4%fat-correctedmilk(P-FCM,kg/day)orNEforlactation(P-NEl,kJ/day)basedonno-interceptversionsofEqs.
(30)–(33)EquationInterceptP-FCMP-NElR.
M.
S.
E.
aAdjusted-R2Signicance(P0.
10).
Thismayinpartrelatetoin-clusioninthedatabaseofgoatsnothighlyselectedformilkproduction,resultinginalargerangeinmilkyield(0.
08–5.
46kg/day)comparedwithdatausedinothersystems(e.
g.
,NRC,1989).
Reportedestimatesofklforlactatinggoatshavebeenquitevariableandinclude0.
69–0.
82(Badamanaetal.
,1990),0.
58–0.
89(SanzSampelayoetal.
,1998),0.
667(Aguileraetal.
,1990),0.
69–0.
70(Hadjipanayiotou,1988a)and0.
62(Economides,1986).
Ourfactorialapproachkl-destimatesbasedonno-interceptregressionsofNEl-dagainstMEl-dof0.
62and0.
58forMethod1and0.
59and0.
55forMethod2withandwithoutadjustmentforMEExN,respectively,arewithintherangeof0.
55–0.
66notedforgoatsandotherruminantsinotherrequirementreports(ARC,1980;AFRC,1998).
EstimatesderivedindirectlyfromregressionofMEl-dagainstFCMdorNEl-dwereslightlygreaterthanfromregressionofNEl-dagainstMEl-d,andwereincloseragreementwithpreviousvaluesnotedforgoats.
Conversely,thosebasedonmultipleregressionanalysisinwhichMEmwasnotassumed(Eqs.
(9)and(11))of0.
70and0.
72wereslightlygreater.
EstimatesofMEl-d/FCMdbasedonno-interceptregressionsinthepresentstudywere4598and4937kJ/kgFCMd(Method1)or4882and5224kJ/kgFCMd(Method2)withandwithoutadjustmentforMEExN,whereasthosefrommultipleregressionanal-ysiswere4298and4384kJ/kgFCM,respectively(Eqs.
(30)and(32),respectively).
Previousesti-matesofMEl/FCMforgoatsaresimilartoonesofthepresentstudy,including4200–4900(Aguileraetal.
,1984,1990)and4712–4838kJ/kgFCM(Hadjipanayiotou,1988a),whichwerederivedusingfactorialapproacheswithoutadjustmentforMEExN.
5.
SummaryandconclusionsWithno-interceptregressionsandemployingMEmproposedbyAFRC(1998),dietaryMErequiredformilkproductionwas4937and4598kJ/kgFCMwith-outandaftercorrectingforMEExN,respectively.
WiththeMEmdeterminedfromestimatesofLuoetal.
(2004b),dietaryMErequiredformilkproductionwas5224and4882kJ/kgFCMwithoutandaftercorrect-ingforMEExN,respectively.
Predictionaccuracywassimilarbetweenmethodsandimprovedslightlybycor-rectionforADG.
Theseestimatesyieldedpredictionscloselymatchingobservedresponsesinmilkyieldandenergywithanevaluationdatasubsetand,thus,shouldhavevaluefordescribingenergyrequirementsoflactatinggoats,particularlyconsideringthelargesizeofthedatabaseusedinthisstudy.
However,forproperemploymentoftheserequirementexpressions,thesameapproachesforpartitioningMEl-dandFCMdisnecessary.
AcknowledgementsThisstudywassupportedbyUSDAProjectNumber9803092.
ReferencesAbijaoudé,J.
A.
,Morand-Fehr,P.
,Tessier,J.
,Schmidely,P.
,Sauvant,D.
,2000.
Inuenceofforage:concentrateratioandtypeI.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273271ofstarchinthedietonfeedingbehaviour,dietarypreferences,digestion,metabolismandperformanceofdairygoatsinmidlactation.
Anim.
Sci.
71,359–368.
AFRC,1993.
EnergyandProteinRequirementsofRuminants.
AnAdvisoryManualPreparedbytheAFRCTechnicalCommitteeonResponsestoNutrients.
CABInternational,Wallingford,UK,pp.
5–55.
AFRC,1998.
TheNutritionofGoats.
TechnicalCommitteeonResponsestoNutrients,ReportNo.
10.
CABInternational,Wallingford,UK,pp.
1–32.
Aguilera,J.
F.
,Guerrero,J.
E.
,Molina,E.
,Boza,J.
,1984.
Efcienciadeutilizacióenergéticaparalactaciónenganadocaprino.
In:9asJornadasCienticasdelaSociedadEspaoladeOvinotecniayCaprinotecnig.
GranadayMálaga:Excas.
DiputacionesProvinciales,pp.
305–310.
Aguilera,J.
F.
,Prieto,C.
,Fonolla,J.
,1990.
ProteinandenergymetabolismoflactatingGranadinagoats.
Br.
J.
Nutr.
63,165–175.
Andrade,H.
,Bernal,G.
,Llamas,G.
,1996.
Inuenceofdifferentalfalfa:sorghumratiosinthedietofdairygoatsonproductivityandrumenturnover.
SmallRum.
Res.
21,77–82.
Andrighetto,I.
,Bailoni,L.
,1994.
Effectofdifferentanimalproteinsourcesondigestiveandmetabolicparametersandmilkproductionindairygoats.
SmallRum.
Res.
13,127–132.
ARC,1980.
TheNutrientRequirementofRuminantLivestock.
TechnicalReviewbyanAgriculturalResearchCouncilWorkingParty.
CommonwealthAgriculturalBureau,FarnhamRoyal,UK,pp.
73–119.
Astuti,D.
A.
,Sastradipradja,D.
,Sutardi,T.
,Haryanto,B.
,1998.
EnergyandproteinrequirementsofgrowingfemaleEtawahcrossbredgoatsdeterminedfrommetabolicparameters.
In:McCracken,K.
,Unsworth,E.
F.
,Wylie,A.
R.
G.
(Eds.
),EnergyMetabolismofFarmAnimals,CABInternational,NewYork,NY,pp.
59–62.
Badamana,M.
S.
,Sutton,J.
D.
,Oldham,J.
D.
,Mowlem,A.
,1990.
Theeffectofamountofproteinintheconcentratesonhayintakeandrateofpassage,dietdigestibilityandmilkproductioninBritishSaanengoats.
Anim.
Prod.
51,333–342.
Baracos,V.
E.
,Brun-Bellut,J.
,Marie,M.
,1991.
Tissueproteinsynthesisinlactatinganddrygoats.
Br.
J.
Nutr.
66,451–465.
Broster,W.
H.
,Oldham,J.
D.
,1981.
ProteinquantityandqualityfortheUKdairycow.
In:Haresign,W.
,Cole,D.
J.
A.
(Eds.
),RecentDevelopmentsinRuminantNutrition.
Butterworths,London,UK,pp.
184–214.
Brun-Bellut,J.
,1997.
Urearecyclingintherumenofdairygoats:effectsofphysiologicalstageandcompositionofintake.
SmallRum.
Res.
23,83–90.
Brun-Bellut,J.
,Blanchart,G.
,Vignon,B.
,1990.
Effectsofrumen-degradableproteinconcentrationindietsondigestion,nitrogenutilizationandmilkyieldbydairygoats.
SmallRum.
Res.
3,575–581.
Ciszuk,P.
,Lindberg,J.
E.
,1988.
Responsesinfeedintake,digestibilityandnitrogenretentioninlactatingdairygoatsfedincreasingamountsofureaandshmeal.
ActaAgric.
Scand.
38,381–395.
Cowan,R.
T.
,Robinson,J.
J.
,Greenhalgh,J.
F.
D.
,McHattie,I.
,1979.
Bodycompositionchangesinlacatatingewesestimatedbyserialslaughteranddeuteriumdilution.
Anim.
Prod.
29,81–90.
Cowan,R.
T.
,Robinson,J.
J.
,McDonald,I.
,Smart,R.
,1980.
Effectofbodyfatnessatlambinganddietinlactationonbodytissueloss,feedintakeandmilkyieldofewesinearlylactation.
J.
Agric.
Sci.
(Camb.
)95,497–514.
Cowan,R.
T.
,Robinson,J.
J.
,McHattie,I.
,Pennie,K.
,1981.
Effectofproteinconcentrationinthedietonmilkyield,changeinbodycompositionandtheefciencyofutilizationofbodytissueformilkproductioninewes.
Anim.
Prod.
33,111–120.
Daniel,C.
,Wood,F.
S.
,1980.
FittingEquationstoData.
seconded.
JohnWileyandSonsInc.
,NewYork,NY,pp.
19–32.
Economides,S.
,1986.
Comparativestudiesofsheepandgoats:milkyieldandcompositionandgrowthrateoflambsandkids.
J.
Agric.
Sci.
(Camb.
)106,477–484.
Eik,L.
O.
,1991.
Effectsoffeedingintensityonperformanceofdairygoatsinearlylactation.
SmallRum.
Res.
6,233–244.
El-Gallad,T.
T.
,Gihad,E.
A.
,Allam,S.
M.
,El-Bedawy,T.
M.
,1988.
EffectofenergyintakeandroughagerationonthelactationofEgyptianNubian(Zaraibi)goats.
SmallRum.
Res.
1,327–341.
Emmans,G.
C.
,1994.
Effectiveenergy:aconceptofenergyutilisationappliedacrossspecies.
Br.
J.
Nutr.
71,801–821.
Emmans,G.
C.
,1997.
Amethodtopredictthefoodintakeofdomesticanimalsfrombirthtomaturityasafunctionoftime.
J.
Theor.
Biol.
186,189–199.
Fernandez,J.
M.
,Sahlu,T.
,Potchoiba,M.
J.
,Lu,C.
D.
,1988.
In:ReportoftheAmericanInstituteforGoatResearch:1985–1988.
LangstonUniversity,Langston,OK,pp.
23–27.
Goetsch,A.
L.
,Detweiler,G.
,Sahlu,T.
,Puchala,R.
,Dawson,L.
J.
,2001.
Dairygoatperformancewithdifferentdietaryconcentratelevelsinlatelactation.
SmallRum.
Res.
41,117–125.
Goetsch,A.
L.
,Puchala,R.
,Lachica,M.
,Sahlu,T.
,Dawson,L.
J.
,2000.
EffectsofdietarylevelsofforageandruminallyundegradedproteinonearlylactationmilkyieldbyAlpinedoesanddoelings.
J.
Appl.
Anim.
Res.
18,49–60.
Hadjipanayiotou,M.
,1984.
Thevalueofurea-treatedstrawindietsoflactatinggoats.
Anim.
FeedSci.
Technol.
11,67–74.
Hadjipanayiotou,M.
,1987.
StudiesonresponsesoflactatingDamascusgoatstodietaryprotein.
J.
Anim.
Physiol.
A.
Anim.
Nutr.
57,52–64.
Hadjipanayiotou,M.
,1988a.
BalancestudieswithlactatingDamascusgoatsofferedavarietyofdiets.
WorldRev.
Anim.
Prod.
24,91–96.
Hadjipanayiotou,M.
,1988b.
Effectofsodiumbicarbonateonmilkyieldandmilkcompositionofgoatsandonrumenfermentationofkids.
SmallRum.
Res.
1,37–47.
Hadjipanayiotou,M.
,1992.
EffectofproteinsourceandformaldehydetreatmentonlactationperformanceofChiosewesandDamascusgoats.
SmallRum.
Res.
8,185–197.
Hadjipanayiotou,M.
,1995.
EffectoffeedingheattreatedsoybeanmealontheperformanceoflactatingDamascusgoats.
SmallRum.
Res.
18,105–111.
Hadjipanayiotou,M.
,Georghiades,E.
,Koumas,A.
,1988.
TheeffectofproteinsourceontheperformanceofsuckingChiosewesandDamascusgoats.
Anim.
Prod.
46,249–255.
Hadjipanayiotou,M.
,Hadjidemetriou,D.
,1990.
Effectoflactationandofroughagetoconcentrateratiosonoutowratesofprotein272I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273supplementsfromtherumenofsheepandgoats.
Livest.
Prod.
Sci.
24,37–46.
Hadjipanayiotou,M.
,Koumas,A.
,Hadjigavriel,G.
,Antoniou,T.
,Photiou,A.
,Theodoridou,M.
,1996.
Feedingdairyewesandgoatsandgrowinglambsandkidsmixturesofproteinsupplements.
SmallRum.
Res.
21,203–211.
Hadjipanayiotou,M.
,Photiou,A.
,1995.
EffectsofproteinsourceandlevelonperformanceoflactatingDamascusgoatsinnegativeenergybalance.
SmallRum.
Res.
15,257–263.
Haque,N.
,Murarilal,Y.
,Khan,M.
Y.
,Biswas,J.
C.
,Singh,P.
,1988.
MetabolizableenergyrequirementsformaintenanceofpashminaproducingCheghugoats.
SmallRum.
Res.
27,41–45.
Hong,B.
J.
,Broderick,G.
A.
,Koegel,R.
G.
,Shinners,K.
J.
,Stuth,J.
W.
,1988.
Effectofshreddingalfalfaoncellulolyticactivity,digestibility,rateofpassage,andmilkproduction.
J.
DairySci.
71,1546–1555.
Hussain,Q.
,Havrevoll,O.
,Eik,L.
O.
,1996.
Effectoftypeofroughageonfeedintake,milkyieldandbodyconditionofpregnantgoats.
SmallRum.
Res.
22,131–139.
Johnson,D.
E.
,Larson,E.
M.
,Jarosz,M.
J.
,1998.
ExtrapolatingfromMEtoNE:unintendedconsequences.
In:McCracken,K.
,Unsworth,E.
F.
,Wylie,A.
R.
G.
(Eds.
),EnergyMetabolismofFarmAnimals.
CABInternational,NewYork,NY,pp.
383–386.
Katipana,N.
G.
F.
,Sastradipradja,D.
,1994.
EnergyandproteinrequirementsofEtawahcrossbredgoatsduringlatepregnancy.
In:EnergyMetabolismofFarmAnimals.
ConsejoSuperiordeInvestigacionesCienticas,Mojacar,Spain,pp.
63–66.
Kawas,J.
R.
,Lopes,J.
,Danelon,D.
L.
,Lu,C.
D.
,1991.
Inueneofforage-to-concentrateratiosonintake,digestibility,chewingandmilkproductionofdairygoats.
SmallRumin.
Res.
4,11–18.
Kiranadi,B.
,Sastradipradja,D.
,Astuti,D.
A.
,Permadi,H.
,1994.
Theeffectofkinggrasssilagewithchickenmanureonthemetabolismandglucoseproductionrateoflactatinggoats.
In:EnergyMetabolismofFarmAnimals.
ConsejoSuperiordeInvestigacionesCienticas,Mojacar,Spain,pp.
71–74.
Louca,A.
,Papas,A.
,1973.
Theeffectofdifferentproportionsofcarobpodmealinthedietontheperformanceofcalvesandgoats.
Anim.
Prod.
17,139–146.
Lu,C.
D.
,Sahlu,T.
,Fernandez,J.
M.
,1987.
Assessmentofenergyandproteinrequirementsforgrowthandlactationingoats.
In:Santana,O.
P.
,daSilva,A.
G.
,Foote,W.
C.
(Eds.
),IVInt.
Conf.
onGoats,DepartamentodeDifusaodeTecnologia,Brasilia,Brazil,pp.
1229–1240.
Lu,C.
D.
,1993.
ImplicationoffeedingisoenergeticdietscontaininganimalfatonmilkcompositionofAlpinedoesduringearlylactation.
J.
DairySci.
76,1137–1147.
Lu,C.
D.
,Potchoiba,M.
J.
,Sahlu,T.
,Fernandez,J.
M.
,1990b.
Performanceofdairygoatsfedisonitrogenousdietscontainingsoybeanmealorhydrolyzedfeathermealduringearlylactation.
SmallRum.
Res.
3,425–434.
Lu,C.
D.
,Potchoiba,M.
J.
,Sahlu,T.
,Kawas,J.
R.
,1990a.
Performanceofdairygoatsfedsoybeanmealormeatandbonemealwithorwithoutureaduringearlylactation.
J.
DairySci.
73,726–734.
Luo,J.
,Goetsch,A.
L.
,Moore,J.
E.
,Johnson,Z.
B.
,Sahlu,T.
,Ferrell,C.
L.
,Galyean,M.
L.
,Owens,F.
N.
,2004a.
Predictionofendogenousurinarynitrogeningoats.
SmallRum.
Res.
53,293–308.
Luo,J.
,Goetsch,A.
L.
,Sahlu,T.
,Nsahlai,I.
V.
,Johnson,Z.
B.
,Moore,J.
E.
,Galyean,M.
L.
,Owens,F.
N.
,Ferrell,C.
L.
,2004b.
Predictionofmetabolizableenergyrequirementformaintenanceandgainofpreweaning,growingandmaturegoats.
SmallRum.
Res.
53,231–252.
Manik,I.
G.
,Sastradipradja,D.
,1989.
Effectofheat-moisturetreatedcassavainureacontainingfeedsupplementoncarbohydrate,proteinandenergymetabolismofgoats.
In:vanderHoning,Y.
,Close,W.
H.
(Eds.
),EnergyMetabolismofFarmAnimals.
CentreforAgriculturalPublishingandDocumantation,PudocWageningen,Netherlands,pp.
73–76.
Moe,P.
W.
,Flatt,W.
P.
,Tyrrell,H.
F.
,1972.
Netenergyvalueoffeedsforlactation.
J.
DairySci.
55,945–958.
Montgomery,D.
C.
,Peck,E.
A.
,1982.
IntroductiontoLinearRegressionAnalysis.
JohnWileyandSonsInc.
,NewYork,NY,pp.
430–437.
NRC,1981.
NutrientRequirementsofGoats:Angora,Dairy,andMeatGoatsinTemperateandTropicalCountries.
NationalAcademyPress.
Washington,DC.
NRC,1989.
NutrientRequirementsofDairyCattle,sixthreviseded.
NationalAcademyPress,Washington,DC.
NRC,2000.
NutrientRequirementsofBeefCattle,7threviseded.
,2000update.
NationalAcademyPress,Washington,DC.
Pailan,G.
H.
,Kaur,H.
,1996.
Inuenceofdietaryproteincontentanddigestibilityonmilkyieldandbloodconstituentsinlactatinggoats.
SmallRum.
Res.
20,47–51.
Prieto,C.
,Aguilera,J.
F.
,Lara,L.
,Fonollá,J.
,1990.
ProteinandenergyrequirementsformaintenanceofindigenousGranadinagoats.
Br.
J.
Nutr.
63,155–163.
Qi,K.
,Lu,C.
D.
,Owens,F.
N.
,1992.
SulfatesupplementationofAlpinegoats:effectsonmilkyieldandcomposition,metabolites,nutrientdigestibilities,andacid-basebalance.
J.
Anim.
Sci.
70,3541–3550.
Randy,H.
A.
,Sniffen,C.
J.
,Heintz,J.
F.
,1988.
EffectofageandstageoflactationondrymatterintakeandmilkproductioninAlpinedoes.
SmallRum.
Res.
1,145–149.
Rapetti,L.
,Crovetto,G.
M.
,Tamburini,A.
,Galassi,G.
,Sandrucci,A.
,Succi,G.
,2001.
Someaspectsoftheenergymetabolisminlactatinggoats.
In:Chwalibog,A.
,Jakobsen,K.
(Eds.
),EnergyMetabolismofFarmAnimals.
WageningenPers,Wageningen,TheNetherlands,pp.
349–352.
Sahlu,T.
,Carneiro,H.
,ElShaer,H.
M.
,Fernandez,J.
M.
,Hart,S.
P.
,Goetsch,A.
L.
,1999.
DietaryproteineffectsonandtherelationshipbetweenmilkproductionandmohairgrowthinAngoradoes.
SmallRum.
Res.
33,25–36.
Sahlu,T.
,Fernandez,J.
M.
,Jia,Z.
,Akinsoyinu,A.
O.
,Hart,S.
,Teh,T.
H.
,1993.
Effectofsourceandamountofproteinonmilkproductionindairygoats.
J.
DairySci.
76,2701–2710.
Santini,F.
J.
,Lu,C.
D.
,Potchoiba,M.
J.
,Coleman,S.
W.
,1991.
Effectsofaciddetergentberintakeonearlypostpartummilkproductionandchewingactivitiesindairygoatsfedalfalfahay.
SmallRum.
Res.
6,63–71.
Santini,F.
J.
,Lu,C.
D.
,Potchoiba,M.
J.
,Fernandez,J.
M.
,Coleman,S.
W.
,1992.
Dietaryberandmilkyield,mastication,digestion,andrateofpassageingoatsfedalfalfahay.
J.
DairySci.
75,209–219.
I.
V.
Nsahlaietal.
/SmallRuminantResearch53(2004)253–273273SanzSampelayo,M.
R.
,Perez,L.
,Boza,J.
,Amigo,L.
,1998.
Forageofdifferentphysicalformsinthedietsoflactatinggranadinagoats:nutrientdigestibilityandmilkproductionandcomposition.
J.
DairySci.
81,492–498.
SAS,1990.
SASUser'sGuide:Statistics,sixthed.
SASInst.
Inc.
,Cary,NC.
Sastradipradja,D.
,Astuti,D.
A.
,Katipana,N.
G.
F.
,Permadi,H.
,1994.
Utilizationofpalmkernelcake,groundkapokseedandsteamedcassava-ureamixassupplementsofgrassdietbylactatinggoats.
In:EnergyMetabolismofFarmAnimals.
ConsejoSuperiordeInvestigacionesCienticas,Mojacar,Spain,pp.
67–70.
Schiavon,S.
,Ramanzin,M.
,Reniero,F.
,Bailoni,L.
,Bittante,G.
,1996.
Relationshipsbetweendeuteriumdilutionspaceandestimatedenergybalanceinlactatinggoats.
SmallRum.
Res.
19,15–22.
Schmidely,P.
,Meschy,F.
,Tessier,J.
,Sauvant,D.
,2002.
Lactationresponseandnitrogen,calciumandphosphorusutilizationofdairygoatsdifferingbythegenotypefors1-caseininmilk,andfeddietsvaryingincrudeproteinconcentration.
J.
DairySci.
85,2299–2307.
Sibanda,L.
M.
,Ndlovu,L.
R.
,Bryant,M.
J.
,1997.
Effectsoffeedingvaryingamountsofagrain/foragedietduringlategestationandlactationontheperformanceofMatebelegoats.
J.
Agric.
Sci.
(Camb.
)128,469–477.
Sutton,J.
D.
,Alderman,G.
,2000.
Theenergyandproteinrequirementsofpregnantandlactatingdairygoats.
TheAgriculturalandFoodResearchCouncilReport.
Livest.
Prod.
Sci.
64,3–8.
Tolkamp,B.
J.
,Ketelaars,J.
J.
M.
H.
,Hofs,P.
,1994.
VoluntaryintakeofdigestibleorganicmatterandfastingheatproductionofWestAfricandwarfgoatsandSwiftersheep.
SmallRum.
Res.
15,45–54.
Teh,T.
H.
,Trung,L.
T.
,Jia,Z.
,Gipson,T.
,1994.
Varyingamountsofrumen-inertfatforhighproducinggoatsinearlylactation.
J.
DairySci.
77,1–6.
Tyrrell,H.
F.
,Moe,P.
W.
,Flatt,W.
P.
,1970.
Inuenceofexcessproteinintakeonenergymetabolismofthedairycow.
In:Proc.
5thSymp.
onEnergyMetabolism,vol.
13.
EuropeanAssoc.
Anim.
Prod.
,pp.
69–71.
Webster,A.
J.
F.
,1980.
Theenergeticefciencyofgrowth.
Livest.
Prod.
Sci.
7,243–252.