Ammoniated rice straw or untreated straw supplemented with a molasses-urea block for growing Sindhi x Local cattle in Vietnam

摘要

Animportanteconomicissue,whichhasnotbeenadequatelyevaluated,istherelativeeffectivenessofammoniationusingureaascomparedwithsupplementinguntreatedricestrawwithamolasses-ureablock.Thepresenttrialwasdesignedtocomparethesetwosystems.Growingcrossbredheifers(SindhiXLocalYellowcattle)werefedeither(ARS)ammoniatedricestraw(ensiledwith2.5kgurea,0.5kgoflime[Ca(OH)2]and0.5kgofsalt/100kgairdrystraw)oruntreatedstrawandamolasses-ureablock(MUB)(finalmolasses50,urea10,salt5,lime8,sugarcanebagasse27%).GrowthrateswereconsistentlyhigherontheammoniatedstrawcomparedwiththeMUBsupplementeduntreatedstraw.Improvementwas25%(P=.001)mainlybecauseofanalmost50%increase(P=.001)inintakeofstrawwhenitwasensiledwithurea.TotalDMintakealsotendedtobehigherwiththeammoniatedstrawtreatment(P=.13)buttheslightdifferencesinfeedconversionwerenotsignificant(P=.42).Onbothtreatmentsthestrawwasofferedatlevelsonlyslightlyexceedingmeasuredintake(about20%above)thustherewaslittleopportunityforselection.Itispossiblethatif,inthepresentexperiment,theuntreatedstrawhadbeenofferedatamuchhigherlevel(100%aboveintake)thengrowthperformancewouldhavebeenthesameonbothtreatmentsbutwithcostadvantagesfortheMUBtreatment.Thishypothesiswillbetestedinthenextseriesoftrialsonthistopic.