The effects of simple processing methods of cassava leaves on HCN content and intake by growing pigs

摘要

Thecompositionoftheleavesoftwentycassavavarieties,takenfromtheupperpartoftheplantatthetimeofrootharvesting,rangedfrom23.7to31.1%forDM,23.7to29.5%forcrudeprotein(inDM)and610to1840forHCN(mg/kgDM).Leavescollectedfromahigh-yieldingvarietyafter60daysofgrowthandatrootharvest(180days)werewiltedfor24hoursfordeterminationofchangesintheDMandHCNcontent.TheHCNlevelwasreducedby58%after24hourswithnodifferencebetweenthetwosourcesofleaves.ThreesimplemethodstoreduceHCNcontentofcassavaleavesbeforefeeding(washing,choppingandwashing;andchopping,washingandwilting)werecomparedinafeedingtrialwith6pigsof25kgmeanliveweight(3MongCaiand3F1[LargeWhite*MongCai])inadoubleLatinsquarearrangement2[3*3)with21-dayperiods.Theleaveswereofferedadlibituminonefeedtroughwithamixtureofensiledcassavarootsandricebran(2:1freshbasis)at80%ofadlibitumlevelinaseparatetrough.Thefreshcassavaleaveswerereadilyconsumedproviding38%ofthedietaryDMandover70%ofthedietaryproteinwithnoeffectofprocessingmethodontotalDMintake,whichrangedfrom27to31g/kgliveweight.LevelsofHCNwerereducedslightly(16%)bywashingandsubstantially(82%)bywilting,resultinginintakesofHCNbetween6.0and15mg/kgliveweight,levelsconsiderablyhigherthanpreviouslyreportedassafetoavoidtoxicity(1.4to4.4mg/kgliveweight).TherewerenoapparentsymptomsofHCNtoxicity.Theresultsindicatethatfreshcassavaleaves,choppedandwashedbeforefeeding,canbeincludedinensiledcassavaroot/ricebrandietsforgrowingpigsatlevelsofupto40%ofthedietDM,andasthesolesourceofsupplementaryprotein.Thelongtermeffectsofthisfeedingsystemhavestilltobedetermined.