4406

4155

كارشناسي ارشد

علوم دامي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1387

يازده ،61[II]ص،مصور ،جدول ،نمودار

ص.ع به :فارسي و انگليسي

محمد علي ادريس ،حميد رضا رحماني

بدر الدين ابراهيم سيد طباطبايي

18/1/87

نفيسه نيلي ،آقا فخر مير لوحي

مهندسي كشاورزي

ID4155

به فارسي و انگليسي : قابل رويت در نسخه ديجيتال

Abstract An important purpose in dairy cattle breeding is reaching to an efficient and economic benefit without increasing the herd size Milk and other dairy products are the most important parts of human foods Therefore increasing production and improvement of milk quality are always the main purpose in milk production industry There are several selection methods which could be used to approach genetic improvement and increase the production and quality of milk products New methods of selection like using genetic polymorphism of genes affecting production traits such as genetic markers along with other common methods of selection can accelerate the genetic improvement process Also increasing selection accuracy and reducing bias rate in evaluation of populations effectively However there are a lot of genes reported affecting milk production and milk contents which can be used as genetic markers such as beta lactoglobulin gene Beta lactoglobulin is a small globular protein of whey protein in ruminants milk which is present in some non ruminants milk too Previous studies have shown this protein is a polymorph in most of dairy cattle breeds which is due to simple replacement of a base pair in beta lactoglobulin gene which could be simply identified by PCR PFLP technique The purposes of this study were to determine the frequency of polymorphism at this locus and its effect on production traits of Iranian Holstein cattle Therefore a total of 234 blood samples were collected from four different farms in Isfahan city and genomic DNA was extracted by modified Miller s method PCR RFLP technique was used to determine the genotypes The segment including the mutation resulting in polymorphism was amplified by specific primers Then 262 bp product was digested by Hae III restriction enzyme Digested product was loaded on 16 non denaturing polyacrylamide gel Presence of segments with 109 and 153 bp referred to A allele and segments with 109 79 and 74 bp referred to B allele The results of allelic and genotype frequencies showed that B allele 0 525 and AB genotype 0 41 were most frequent ones To study the effects of genotype SAS software Proc GLM was employed In the linear model of analysis the effects of herd and genotype were considered as the fixed effects and days in lactation dry period and open days were considered as the covariables Among milk production and milk contents traits reproduction and birth weight genotypes were only significantly effective on birth weight P 0 05 and crude milk production P 0 10 AA genotype had the highest relationship with higher crude milk production as well as higher birth weight which might be considerd in selection index for suitable genotype selection of these traits

محمد علي ادريس ،حميد رضا رحماني

بدر الدين ابراهيم سيد طباطبايي

نفيسه نيلي ،آقا فخر مير لوحي