9487

8769

كارشناسي ارشد

كشاورزي- علوم دامي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1393

ده،44ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

علي صادقي سفيدمزگي

حسين مهربان، رحمان جهانيان

1/11/93

سعيد انصاري مهياري، محمدرضا سبزعليان

مهندسي كشاورزي

ID8769

Genetic and Economic Aspect of Lactation Persistency in Holestein Dairy Somayeh Hasanvand Somayeh hasanvand@ag iut ac ir Departement of Animal Science College of Agriculture Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiA Sadeghi Sefidmamazgisadeghism@cc iut ac irAbstractThe objectives of this study were to 1 estimate variance componets and phenotypic and genetic trends forpersistency 2 estimate phenotypic and genetic correlation between profitability and persistency and 3 calculate economic value for milk persistency in Holestein dairy cattle population of Iran In order toestimate genetic parametersand trends forthe persistency a total of 2487378 milktest day records of 336 164first calving Holstein cowsfrom2581 herds that calved during the years 1992 to 2012were used Theestimated parameters of Wood function were used to calculate persistency Fixed environment effects wereexamined by SAS software Variance components and heritability were performed using Wombat softwareon the base of univariate animal model Additive genetic and phenotypic variance and heritability wereestimated to be 0 03 0 37 and 0 08 respectively Genetic and phenotypic trends were 0 022 and 0 01 respectively and both of them were statistically significant P 0 05 The results of current study showed thatthe persistencyof Iranian Holstein cowsover these years had a favorable and positive genetic andphenotypictrend To calculate the economic value profitabilty and persistencyrecords belongingto182 521first calving Holstein cows from 2000 to 2011 were used To do this revenues costs andprofitabity were calculated in term of per cow per year that were 65 581 118 37 083 615 and 28 497 503IRls respectively Then anual profitabilty was regressed on persistency to give an estimate of economicvalue using multiple analysis of covariance generelized linear model presidure Proc GLM of SASsoftware The conomic value per standard deviation of persistancy was estiamted to be 1 196 750 IRls Bymeans of BLUPF90 on the base of a bivariate animal model phenotypic and genetic correlation betweenprofitability and persistencywere estimated to be 0 04 and 0 58 respectively Obtained results in the researchcan be useful in evaluation and determination of breeding programs for milk persistancy in Holestein dairycattle population of Iran Keywords variance components milk production traits heritability economic value

علي صادقي سفيدمزگي

حسين مهربان، رحمان جهانيان

سعيد انصاري مهياري، محمدرضا سبزعليان