6794

6336

كارشناسي ارشد

علوم دامي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده كشاورزي

1390

يازده،56ص.: مصور،جدول

ص.ع.به فارسي و انگليسي

محمدعلي ادريس، سعيد انصاري

حميدرضا رحماني، بدرالدين ابراهيم سيدطباطبايي

7/4/91

امير حسين مهدوي، مجيد طالبي

مهندسي كشاورزي

ID6336

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

AbstractMilk fatty acid composition is a parameter of great interest for evaluation of nutritional quality of milk Stearoyl CoA desaturase 1 SCD1 also known as 9 desaturase is a key enzyme in mammary lipidmetabolism because it is able to add a double bond in the 9 position in a large spectrum of medium and longchain fatty acids With regard to the role of SCD1 in lipid metabolism and QTL studies for milk productiontraits SCD1 has been regarded as a candidate gene related to milk production traits in dairy cattle Onepolymorphism SNP in exon 5 region of this gene might control translation or stability of SCD1 mRNA Thispolymorphism is the result of substitution of valin allele V with alanine allele A In the case of being alanine there will be a restriction site for the restriction enzyme NcoI and as a result alleles A and V will berecognizable as bands with length 200bp and 400bp respectively To investigate this polymorphism and itsrelationship with milk production traits blood sample from 408 Holstein cattle in 5 industrial dairy farmslocated in Isfahan province that had records for milk production and composition for first parity was randomlytaken Genotyping was done by PCR RFLP technique After extracting DNA to determine the quality andquantity of extracted DNA amplification and digestion by restriction enzyme digestion product was observedon 1 5 agarose gel Both alleles A and V were observed in all 5 herds and which their frequencies were 0 58and 0 42 respectively Frequency of genotypes AA AV and VV were also 0 26 0 65 and 0 09 respectively Thefrequency of genotypes was not in Hardy Weinberg equilibrium Disequilibrium shows Herds could be underselection and the selection may indirectly affect SCD1 gene which cause disequilibrium for milk production andprotein percentage Genetic analysis of the population was done by the PopGen32 software Results indicate ahigh diversity within this polymorphism and a high inbreeding and genetic relationship within the studiedpopulation To investigate the effect of genotype on production traits SAS software procedure GLM wasemployed In analysis the effects of genotype and combined effect of herd year and season of parturition wereconsidered as fixed effects and days in milk and open days were considered as co variables Genotype hadsignificant effect on corrected milk production and protein percentage P 0 01 Individuals with genotype VVhad statistically more milk protein percentage and corrected milk production in comparison with genotypes AVand AA Also cows having genotype AV showed more milk protein percentage and corrected milk productioncompared to genotype AA These findings show that this polymorphism could be considered as an additive geneaction Dominance effect for the studied traits was not significant P 0 05 which confirmed additively of thepolymorphism As there were a good relationship between the polymorphism with protein percentage andcorrected milk production and also a high diversity within the studied population this polymorphism can beused as a selection tools for these traits Key words SCD1 Gene Holstein Cattle Genotype Polymorphism

محمدعلي ادريس، سعيد انصاري

حميدرضا رحماني، بدرالدين ابراهيم سيدطباطبايي

امير حسين مهدوي، مجيد طالبي