production of a cow mostly depends on number of milking period times amount of milk production per period. Many factors such as genetic, physiologic and environmental factors and manner of farm management can affect on pregnancy rate. However, finding of the main reasons for low reproduction’s efficiency are very difficult due to many complicated factors affecting on. Among important factors affecting reproduction rate are factor XI (FXI) and Diacylglycerol acyltransferase (DGAT1). Factor XI is a blood coagulation factor and deficiency of this factor may decrease growth of ovarian follicle. A QTL has been mapped consistently to the centromeric region of the bovine chromosome 14 that appears to have a main positive effect for variation in fat content of milk. The DGAT1 encodes for acylCoA-diacylglycerol-acyltransferase 1, an enzyme that catalyses the final step of triglyceride synthesis. It was proposed to be a strong candidate gene underlying this effect, due both to its appropriate chromosomal location and the fact that knock out transgenic mice lacking both functional alleles of DGAT1 were totally devoid of lactation. The objective of this study was to determine FXI and DGAT1 genes polymorphism and the relationship with Holstein dairy cow’s reproduction traits. Blood samples were collected from 120 Holstein cows of four different herd management in Isfahan region (94 cows had repeat breeding failure and 26 cows were randomly selected). Isolation of genomic DNA was performed using a salting-out method. For FXI gene no mutant alleles have been identified and all of these samples showed a single 244bp band. The polymerase chain reaction was used to amplify the 378bp DNA fragments from genomic DNA for DGAT1 gene. PCR products were digested with BglI enzyme. At the DNA level it is caused by double substitution at the nucleotide position 10433 and 10434 in exon 8, alanine instead of lysine. lysine encoding allele ( K ) was visible in gel as two bands of 282bp and 96bp. Alanine encoding allele ( A ) was cleaved into three fragments of 254bp, 96bp and 28bp. The frequency of AA, AK and KK genotypes was 0.59, 0.34 and 0.06, respectively. The K and A alleles frequencies were 0.23 and 0.77 respectively in Holstein cattle. Mixed model analysis was used to estimate the effect of the DGAT1 K232A polymorphism for milk production and reproductive traits The K232A polymorphism was significantly associated with percentage of milk and length of pregnancy and not shown to be significantly associated with any other traits.
