Additive, heterosis and reciprocal effects on egg production and quality of exotic x indigenous crossbred chickens in Tanzania

摘要

AstudywasconductedincentralTanzaniatoassesseggproductionandqualityperformance,additivebreed,heterosisandreciprocaleffectsforgeneticstocksarisingfrom4x4diallelcrossesfromfourparentalstocks(twoexoticandtwoindigenouschickens).Thedataoneggproductionandqualitywererecordedonindividualbirdbasisandwereanalyzedusinggenerallinearmodelsprocedures.nbsp;Theresultsrevealedthatthedifferencesbetweengeneticstocksweresignificantforageatsexualmaturity(ASM),firsteggweight(FEW),averageeggweightat48weeksofage(EWT48),eggshellthicknessat48weeksofage(EST48)andnumberofeggsin90daysoflayingafterattainmentofsexualmaturity(EN90).Nosignificantdifferenceswereobservedbetweengeneticstocksfornumberofeggsin180daysoflayingafterattainmentofsexualmaturity(EN180)andeggshapeindexat48weeksofage(ESI48).Indigenouschickensfromthewarmecologicalzone(WW)laideggswiththickershellsat48weeksofage(EST48)andmaturedearlier(140days)thanothergeneticstocks.ThehighestEWT48wasobservedinbroilerstock(56.3g),followedbythecrossbetweenBroilerandBlackAustralorp(54.1g)whileindigenouschickensfromthewarmzone(WW)hadthelowest(42.5g).Thecrossbetweenindigenouschickensfromthewarmecologicalzoneandbroiler(WB)hadmoreeggsat90dayspostsexualmaturitythanothergeneticstocks.TherewerenostatisticaldifferencesbetweengeneticstocksinEN180butthecrossbetweenbroilerstocksandindigenouschickensfromthecoolecologicalzone(BC)followedbythecrossbetweenbroilerandBlackAustralorpchickens(BA)showedbetterperformanceinthistrait.AdditivebreedconstantestimatesforthebroilerstockswerehigherthanthoseofotherstockswithrespecttoFEWandEWT48whiletheBlackAustralorpstockshadslightlyhigheradditiveconstantestimatesforEN90andEN180.Thecrossbetweenindigenouschickensfromthecoolzoneandbroiler(CB)aswellasthecrossbetweenindigenouschickensfromthewarmecologicalzoneandbroiler(WB)exhibitedpositiveheterosisinEN90andEN180.ReciprocaleffectswereobservedforthecrossbetweenBlackAustralorpandindigenouschickensfromthecoolecologicalzoneinFEWaswellasthecrossbetweenBlackAustralorpandBroilerstock(AB)inEST48.ItisconcludedthattheuseofbroilerassiresandeitherindigenouschickensorBlackAustralorpasdamsproducedcrossbredsthatweregoodinFEW,EWT48andEN180whiletheuseofbroilerasdamsandindigenouschickensfromthewarmecologicalzoneassiresfavoredEN90.