Feeding urea treated barley straw to growing Friesian heifers

摘要

EleventrialswithgrowingFriesianheifersofdifferentageswerecarriedout.Intrials1,2and6,thevoluntaryintakeofuntreated(US)andurea-treatedstraw(UTS)wasmeasuredwithFriesianheifersofferedaconstantallowanceofaconcentratemixture.Theeffectoffeedingahigh(HP)orlowprotein(LP)concentratemixturealongwithUSorUTS,respectivelywasstudiedinfourtrials(trials3,9,10and11).Inanotherthreetrials(trials4,5and7),UTSofferedwithaLPcontentconcentratemixturewascomparedwithUSgivenalongwithaHPmixtureprovidedbysoybeanmeal(HP)oracombinationofsoybeanmealandurea(LP+U).Finally,intrial8theeffectofcompletereplacementofbarleyhaybyUTS,bothofferedadlibitum,wasstudiedovertheperiodof4-6monthsofage.UTShadgreatercrudeprotein(98vs43g/kgDM)andinvitrodigestibility(53.2vs44.9%)thanUS.VoluntaryintakeofUTSwasgreaterby3.2%(trial1),8.6%(trial2)and10%(trial6)comparedtoUS.Therewasnodifference(trials3,6,9,10and11)intheperformanceofheifersonUSandUTSfedalongwithaHPandLPmixture,respectively.Withtheexceptionoftrial5,therewasanoverallincrease(12.4%)inweightgainofheifersontheurea-treatedthantheurea-supplementeddiets.Finally,UTSsuccessfullyreplacedbarleyhay(trial8).Basedonanimalperformancedata,andthefeedingcostsobtainedinthepresentstudies,ureatreatmentexpensesrangingfromCYP12.04-45.80maybejustified.Itisconcludedthatundercertainconditionsureatreatmentofstrawiseconomicallyviableandtreatmentmayenhancestrawutilization.