Replacing soya bean meal with cassava leaf meal in cassava root diets for growing pigs

摘要

Cassavaleafmealwasusedtoreplacetheproteinofsoyabeanmealatlevelsof0,35,70and100%inadietforgrowingpigsbasedoncassavarootmeal.Theoverallproteinlevelwasrestrictedto11%(DMbasis).Fourcastratedpigs(LargeWhite)of50kgwereusedina4x4LatinSquarearrangementofthetreatments.Theexperimentalperiodswere12days,thefirst7foradaptationtothedietandthelast5fortotalcollectionoffaecesandurine.Duringtheadaptationperiodthepigswereinconcretefloorpenswhileforcollectionofexcretatheywereinmetabolismcages.Feedingwasadlibitumduringtheadaptationperiodandrestrictedduringtheexperimentalperiodtothemaximumeatenbythepigontheleastpalatablediet(usuallythatwith100%cassavaleafmeal).Thecassavaleafcontainedindrymatter:22%Nx6.25and15.5%crudefibre.TheHCNcontent(DMbasis)wasreducedbysun-dryingfrom190mg/kginthefreshleafto20mg/kgintheleafmeal.ThereweresignificantdifferencesinapparentdigestibilityofallnutrientswithlineardecreasesasCLMlevelswereincreased.Thedegreeofdepressionwasmuchmoremarkedforproteinandforetherextractthanfortheotherelements.ExcretionofNinfaeceswassignificantlyhigher,andinurinesignificantlylower,forthethreedietscontainingCLM.DailyNretentiondidnotdifferbetweendietswith100%soyabeanmealand65%proteinfromsoyaand35%fromCLM.Dietswithhigherratesofsubstitution(70and100%CLM)supportedsignificantlylowerNretention.WhenNretentionwasadjustedfordailyamountofNdigested,thenthedietwith35%proteinfromCLMwassignificantlybetterthanthecontrol(0%CLM)andthe100%CLMdietbutdidnotdifferfromthe70%CLMdiet.Theresultssuggestthatnitrogenbalanceingrowingpigsfedacassavarootmealdietisunaffectedwhencassavaleafmealreplacesupto35%oftheproteinfromsoyabeanmeal.Thelowerdigestibilityofthecassavaleafprotein,comparedwithsoyabean,isapparentlycompensatedbyasuperiorbiologicalvalue.