Phosphorus concentrations in blood, milk, feces, bone and selected fluids and tissues of growing heifers as affected by dietary phosphorus

摘要

EffectsofdietaryPonconcentrationsofPinblood,milk,feces,bone,saliva,rumenfluid,varioustissuesandhairofgrowingAngusheiferswereevaluated.Thedurationoftheexperimentrangedfrom525to772ddependingonslaughterdateofindividualanimals.Initially,14weanedAngusheiferswerefedquot;adlibitumquot;alow-Pdiet(0.10%P,drybasis)for270d.Heifersweresubse-quentlyallottedrandomlyintotwogroups(sevenanimals/group)andreceivedeither0.12%P(lowP)or0.20%P(adequateP)(drybasis).Theexperimentalperiodwas245dofthetreatmentphasefornon-pregnantanduntil3weekpostpartumforpregnantheifers.Serum,plasmaandwholebloodPconcentrationsvariedthroughouttheexperimentbut,generally,tendedtoreflectdietaryPaddition.Forthemajorityofthesamplingperiods,bothtreatmentgroupswereabletomaintainacceptednormalserumandplasmaPconcentrations.Liver,kidney,heart,muscle,rumenfluid,fecesandhairPlevelsprovedinsensitivefordistinguishingbetweentreatmentgroups.DietaryPlevelhadnoeffectonPorCacontentofmilk.SalivaPconcentrationwasrelatedtotreatmentgroupsforbothsamplingperiods.RibbonePexpressedaspercentashormilligramP/cm3wasgreater(P0.05)foranimalsreceivinghigherdietaryP.Oftheparametersstudied,bonePconcentrationbestreflecteddietaryPintake.