Feeding behaviour of layer hens supplemented with snail or oyster shells in the last laying phase: effects on egg quality

摘要

Theexperimentaimedtoevaluatetheeffectsofadditionalbiologicalsourcesofcalciumtohensbetween60to72weeks-old,oneggproductionandeggquality.Atotalof72ISABrownhenshavinganaveragelayingrateof86.6±4.14%weredividedinto4dietarytreatmentsgroupsinwhichoystershells(OandO+)andsnailshells(SandS+)wereused.IndietarytreatmentsO+andS+,henswerefedwithabalanceddietandsupplementedwithoysterandsnailshells,respectively,throughfreechoice-feedingsystem.CompletelyRandomizedDesignwasused.HenswerehousedinCaliforniancagesandeachdietwasdeliveredtoninecages(replications)oftwohenseach.Thesupplementationofshellssignificantlyincreasedthedailyintakeofcalciumperhenandperegg.ComparedtothecontroldietsSandO,theintakeofbalancedfeedsignificantlydecreasedinS+andO+,respectively.Theintakeofcrudeproteinandmetabolisableenergysignificantlydecreasedinoystershelldietarytreatments;butnotinsnailshellones.Irrespectiveofthetypeofshell,nosignificanteffectofshellsupplementationwasrecordedonfeedconversionratioandlayingrate.ThelayingrateimprovedsignificantlyinO+comparedtoS+.Snailshellsupplementation,significantlyimprovedtheeggweight(60.8versus63.4ginSandS+,respectively);but,thatofoystershelldidnot.Nosignificanteffectofshellsupplementationwasnoticedonthickness,weight,percentageandindexofeggshell.TheHaughunitandalbumenheightofeggweresimilar.Economically,thesupplementationofsnailshellsignificantlyreducedtheefficiencyofdiet.Itcanbeconcludedthat,despitetheincreaseofcalciumintakeof,thesupplementationofsnailoroystershellstoISAbrownagedlayerhensdidnotsignificantlyimproveeggshellcharacteristics;but,thatpracticeincreasetheeggweightinhensfedwithsnailshell.