Effect of offer level of Kikuyu grass (Pennisetum clandestinum) on production, milk quality and nitrogen balance in Holstein cows

摘要

Totesttheeffectoftwopastureallowance(PA)onmilkproduction(Mprod)andcomposition,andnitrogenbalance(N)inHolsteincowsgrazingkikuyugrass,astudywasconducedwithsixcowswithtwoormoreparturitioninsecondmonthofnursing(188.5±41d)randomlyassignedtotwotreatments:2.5(L)and3.5kgofdrymatter(MS)/100kgofbodyweight(BW)(H)inacross-overdesignwithtwo14daysperiodsand25daysbetween-periods.Duringthreedaysbeforebegantheexperimentalperiod,themilkproductionwasregistered,cowswereweighted(BW)andbodyconditionscore(BCS)weredetermined.Elsewhere,milksampleswererecollectedandanalyzedtoproteinandfat,andfaecalsampleswereanalyzedtobasalchromiumcontent.Then,thecowswereindividuallyallocatedinakikuyuprairieusingmetallicwandsandtiedwithabowfixedtoneck.Thecowsweresupplementduringthetwomilking,supplysimultaneously5.0gofchromicoxide.Duringthelastfourdaysofeachexperimentalperiodwerecollectedindividualsamplesofmilkandanalyzedtoprotein,fat,totalsolids,urea,cheeseyieldandcheeseproteincontent.Elsewhere,werecollectedfaecessamplesandanalyzedtoN,non-degradableneutraldetergentfiberandchromiumaswellasurinesamplesthatwereanalyzedtoN,creatinineandallantoincontent.RuminalfluidsampleswerecollectedthelastexperimentaldayandanalyzedtopHandammoniumcontent.Elsewhere,eachcowwasweightedandbodyconditionscored.Itwascalculatedthepasturedrymatterintake(pDMI),totaldrymatterintake(tDMI)andsubstitutionrate(ST).ItwasestimatedtheNintake(Nint),Ninfaeces(Nfae),Ninurine(Nurin),Ninmilk(Nmilk),Nreplenished(Nrep),theNefficiencytomilkproteinproduction(Neffic)andmicrobialproteinsynthesis(Mprot).TheCMSFwaslowerincowsoftheOFBajatreatmentaswastheCMST(p0.01).TreatmentsdidnotaffectthePDCN,theGCCandtheLWoftheanimals.Therewasalsonoeffectoftreatmentsonthequalityofmilkandrumenactivity.ThetreatmentOFBajahadgreaternbsp;EUN(p0.02)withoutaffectingothervariablesoftheNbalance.Itwasconcludedthat3.5PA,comparedwith2.5nbsp;kg,nbsp;improvedNintandreducedNefficbutdidnotaffectBW,Mprodnormilkcomposition.