3602

3405

كارشناسي ارشد

علوم دامي

اصفهان : دانشگاه صنعتي ، دانشكده كشاورزي

1385

هفت ، 57، [II] ص: جدول

ص. ع. به فارسي و انگليسي

مهندسي كشاورزي

ID3405

فارسي و انگليسي: قابل رويت در نسخه ديجيتال

Abstract This study was conducted to determine the genetic correlation between age at firstcalving and some productive milk yield milk fat yield and percent and reproductive open days dry period and calving interval traits The data were used in this study include534857 records of productive traits and 475589 records of reproductive traits in 3 firstlactation of Isfahanian Holstein dairy cows The DFREML software package was used toanalysis data set To estimate genetic and phenotypic parameters the SIMPLEX methodand No 7th animal model were used for univariate and multivariate analyse respectively The average and heritability of age at first calving were calculated to be 26 57 and 0 55respectively The heritability of milk yield milk fat yield and fat percent in differencelactation period were 0 11 0 15 0 13 0 21 and 0 17 0 25 respectively The heritabilityof maternal effects and fix environmental effects was calculated in univariate analysis Thegenetic correlations of productive traits in different lactation period exhibited reductionaltrend The genetic correlation between age at first calving and milk yield milk fat yield fatpercentage open days calving interval and dry period in second lactation period werecalculated to be 0 19 0 13 0 16 0 11 0 056 and 0 043 respectively however thesecorrelations in third lactation period had almost reductional trend All calculatedcorrelations between age at first calving and other studied traits had significant differencesin all 3 lactation period P 0 05 Because of positive genetic correlations with productivetraits age at first calving could affect animal productive performance

محمد علي ادريس

غلامرضا قرباني ، محمد مهدي محمد علي پور

مسعود عليخاني، عبدالمجيد رضايي