Effect of kikuyo (Pennisetum clandestinum) or ryegrass (Lolium hibridum) intake on conjugated linoleic acid concentration and fatty acids composition of milk fat

摘要

Theeffectofgrazingryegrassorkikuyowithtwocuttingagesonbovinemilkproductionandfattyacidcompositionofmilkfat,includingconjugatedlinoleicacid(CLAcis9trans11)wasevaluated.Threepastures(treatments)(30Holsteincows;10pertreatment)wereusedconsistingof:1)ryegrass,cuttingage45day,2)kikuyucuttingage50daysandnbsp;3)kikuyu70dayscuttingage.nbsp;Astripgrazingsystemwasusedwithaconstantforageofferof4kgDM/100kgnbsp;LW/daythatwasregulatedwithanelectricfence.Theexperimentlasted29days,15daysofpre-experimentalperiodwherethecowsweregrazingkikuyuandwereadaptedtofeedsupplementfollowedby14daysofdatacollection.nbsp;Intakeofkikuyuwasestimatedusingchromiumoxideasexternalmarkerandindigestibleaciddetergentfiber(iADF)asinternalmarker.nbsp;Totaldrymatterintakewas15.8,14.9y13.4Kg/dayforcowsgrazingK50,K70andR45respectively(P0.05).AhighermilkproductionwasobservedincowsgrazingryegrassandK50thanforcowsgrazingK70(P0.05).Milkprotein,milkfat,polyunsaturatedfattyacids,andCLAconcentrationwerehigherincowsgrazingkikuyuthanintheonesgrazingryegrass.MilkCLAconcentrationwashigherforcowsgrazingK50thanforcowsgrazingK70(p0.1).