The DGAT1 catalyzes the final step of triglyceride synthesis and is located on centromic end of bovine chromosome 14. The substitution AA to GC in exon VIII changes Lysine to Alanine. The allele K affects fat yield, percent of fat and protein, allele A affects the yields of milk and protein. Samples of semen from 103 bulls were genotyped. A 411bp fragment from exon VIII was amplified and digested by AcoI with PCRRFLP method. The frequencies of KK, KA and AA were 0.592, 0.408 and zero respectively. The frequency of alleles K and A were 0.7961 and 0.2039. The PCR product of KK genotype was sequenced. The sequence of allele K of DGAT1 gene was registered in NCBI gene bank with accession number EU077528. The first lactation records of 43303 dairy cattle from 1999 to 2006 were used for prediction BV under Animal Model with DFREML software. The average BV for yield of milk, fat and protein, percent of fat and protein were 180.2 (±28.8) kg, 3.7 (±1.26) kg, 2.3 (±1.06) kg, -0.036% (±0.014) and -0.03% (±0.01), respectively. The association between BV of the bulls and the genotypes for DGAT1 gene were studied with GLM procedure of SAS package. The average BV of milk yield for KA and KK genotype were 288.8 and 109.6 kg (P<0.01) and for fat yield were 5.6 kg (KK) and 0.91 kg (KA) (P>0.05). The difference between BV of protein yield for KK (5.5 kg) and KA (0.025 kg) was significant (P<0.05). The average BV of fat percent were -0.009% (for KK genotype) and -0.067% (for KA genotype) and the difference of means was significant (P<0.05). The differences of these values for percent of protein for KK (-0.0158%) and KA (-0.0597%) were also significant (P<0.05).

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