Effects of targeted phase supplementary feeding on gut morphology of scavenging ecotypes of indigenous chickens in Kenya

摘要

Indigenouschickens(IC)dependonnutrientsscavengedforgrowthandeggproductionbutscavengingalonedoesnotprovidesufficientnutrientsforbothmaintenanceandhighproduction.FeedinginterventionstoimproveproductivityhavebeenapplieduniformlywithoutconsideringthedifferentgrowthphasesthoughICexhibitpointsoflowandhighratesofgrowthalongtheirgrowthcurves.Thisstudywasdesignedtoprovideascientificbasisforfeedingstrategiesthatexploitthemorphologicaladaptationsinducedbytherequirementsforimprovedgrowthrates.Theobjectivewastodeterminetheeffectoftargetedphasesupplementaryfeedingongutmorphologicalcharacteristicsatdifferentgrowthphases.Feedingtrialswereconductedforaperiodof21weekswithsupplementationatthreegrowthphases(5-8weeks(TRT2),9-14weeks(TRT3)and15-21weeks(TRT4))whileleavingthechickenstoscavengefortherestofthegrowingperiod.Thecontrolgroup(TRT1)waslefttoscavengefortheentirestudyperiod.Threechickensineachphasewererandomlyselectedforexaminationofhistologyofdigestivesystem.Theweightofthegizzard,lengthofthesmallintestines,andnumberofthevillipercm2inthethreesectionsofthesmallintestinesweremeasured.Treatmentsignificantlyaffectedtheintestinalmorphologyintheduodenumsectiononlybutithadnosignificanteffectonthejejunumandileum.Thevillipopulationwashighestintheduodenumsectionsuggestingthatthiswasthemostactivesectioninnutrientabsorption.Thecontrolgroup(TRT1)inbothICecotypeshadthehighestgizzardweights(11.13and10.71g/KgliveweightforKakamega(KK)andBondo(BN)respectively).Thesamegrouprecordedthehighestmeanintestinallengthinbothecotypes(104.36and113.95cm/KgliveweightforKKandBNrespectively).