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1、InternationalDairyJournal9(1999)709}713Correlationbetweeni-caseinvariantsandcitratecontentinmilkquanti"edbycapillaryelectrophoresisMartinBraunschweig*,ZdenkoPuhanLaboratoryofDairyScience,SwissFederalInstituteofTechnology,CH-8092Zurich,SwitzerlandReceived9April1999;accept
2、ed7October1999AbstractThemilksofcowswithknowngeneticvariantsofproteinswerequanti"edbycapillaryelectrophoresis(CE)forcitratecontent.Fromseventest-bullsofthebreedSwissBrown]BrownSwiss(SB]BS)withthetwocaseinhaplotypesB-A-B-AandB-A-B-Bfora-,a,-,b-,andi-casein(CN),137daughter
3、swereselected.Theywereassignedintotwogroupsaccordingtothecaseinhaplotype4142inheritedfromthefather.Duringthe"rstlactation,fromeachcow,twomilksamples,i.e.between30}80and170}215dayswereanalysedforcitratecontent.Fromthedataobtainednocorrelationbetweenthecaseinhaplotypeandth
4、ecitratecontentinmilkwasfound.Thesameapplieswhenthecowsweregroupedaccordingtoi-CNgenotypesAA,ABandBB.Thecitratecontentinthesecondintervalbetween170and215dayswasforallcowssigni"cantlylowerthaninthe"rstinterval(30}80days)ofthelactation.(2000PublishedbyElsevierScienceLtd.Al
5、lrightsreserved.Keywords:Citratecontent;Capillaryelectrophoresis,Milkproteinvariants1.Introductioncomplexeswithcalciumions,investigationswerefocusedonthecontentofcitrateini-CNAAversusi-CNBBCitricacidisknownforitskeyroleinthemetabolismmilk.Milkwithi-CNAAwasfoundtocontains
6、igni"-ofplantandanimalcell.Thesynthesisofmilkoccursincantlymorecitratethani-CNBBmilk(Marianietal.,thealveolarcellsoftheudderandtheconcentrationof1976;Mariani,Losi,Morini&Castagnetti,1979;Hans-citrateincowmilkisabout90foldofthatinblood.Theson&Pettersson,1985).Incontrastto
7、this,inanothermeancontentofcowmilkhavebeenreportedtobestudythesigni"canceofthecorrelationbetweencitrate1.7}1.9gL~1(Jenness,1988).Citrateformsinmilksaltscontentandthegeneticvariantsofi-CNhasnotbeenwithcalcium,magnesiumandtoamuchlesserextentcon"rmed(Remeuf,Cossin,Dervin,Le
8、noir&Tomas-withsodiumandpotassium.About7}10%ofthetotalsone,1991).Jakob(1993)alsoreportedthattherewasnoc
