Prediction of some Tunisian roughages voluntary intake by heifers and ewes from chemical composition and ruminal degradation characteristics

摘要

Thepresentstudyaimsatpredictingthevoluntaryintakeofdifferentroughagesbyheifersandewes.RationsbasedonEgyptianclover(Trifoliumalexandrium),oat(avenasativa),barley(Hordeumvulgare)Souihli,barlyManel,vetch(Viciasativa)-oatsilage,andvetch-oathayweredistributedadlibitumtwiceadayduringthreeperiodsof4weekseachto6Holsteinheifers(age=14monthsandaveragebodyweight=360kg,STD=51kg).Heifersand6black-Thibarewes(age=48monthsandaveragebodyweight=57Kg,STD=7.85kg).nbsp;Heifersandewesregimenwereenrichedby30g/kgLW0.75nbsp;and10g/kgLW0.75ofconcentraterespectively,andby50g/animaldailyofcommercialmixtureofmineralsandvitaminsforeachanimal.Chemicalcomposition(DM,CP,NDF,NDSandCF)wasdeterminedforeachroughage.Ruminaldegradabilityoftheseroughageswasdeterminedusingthetechniqueofnylonbagsandwasnbsp;modelledas:Dg=nbsp;a+b(1-e#8211;ct),whereDgistheruminaldegradabilityintimetanda,bandcareconstants.TheCPandNDFcontentsrangedfrom7.6to19.1%DMandfrom42.0to56%DM,respectively.FortheDgparameters,thefraction#8220;a#8221;rangedfrom5.2to23.5;thefraction#8220;b#8221;rangedfrom51.1to71.2and#8220;c#8221;rangedfrom0.0114to0.0570.Thereweresignificantdifferences(p0.05)amongroughageswithregardtoimmediatelysolublefraction#8220;a#8221;,insolublebutdegradablefraction#8220;b#8221;,andfractionrateofdegradation#8220;c#8221;.Thevoluntaryintakeofroughagesbyheifersrangedfrom5821gDMto9873gDMdaily.Averagesilageintakeswere6884gDMdaily.Thislowvaluemayberelatedtothequalityofroughageconservation.Thevoluntaryintakeofroughagesbyewesrangedfrom784gDMto1104gDMdaily.TheintakeofbarleySouihliwashigher.Roughageintakecanbepredictedbasedonchemicalcharacteristics.TheMATandtheNDScontentswithruminaldegradabilityparametersexplained52%ofthetotalvariationofroughageintakebyHolsteinheifers.Roughageintakebyewescanbepredictedbasedontheirchemicalandbiologicalparameters.