Abstract:

【Objective】 Analysis of association between DGAT1 gene and milking traits for Chinese Holstein in the south of China was investigated. 【Method】 The polymorphism of the K232A site in exon 8 of DGAT1 gene was investigated in 605 Chinese Holstein cows from 30 bull families in Jinshan Dairy Farm of Shanghai Bright Dairy Group using PCR-SSCP, and with a mixed animal model, the effects of the polymorphism of the K232A site on test-day milk yield, fat percentage, milk protein percentage, 305 days corrected milk yield, milk fat yield, milk protein yield and SCS were analysed. 【Result】 Three genotypes were found and the genotypic frequencies of KK, KA and AA were 0.7918, 0.1917, and 0.0165, respectively. The gene frequencies of K and A were 0.8876 and 0.1124. The very significant association of the DGAT1 K232A with tested day milk yield, milk fat percentage, 305 days corrected milk yield and milk protein yield (P＜0.01), and significant association with milk fat yield were identified, and had no significant effect on the SCS in milk (P＞0.05). LSD showed that the cows with KK and KA genotypes had higher tested day milk yield, 305 days corrected milk yield and milk protein yield than those with AA genotype (P＜0.01),while had lower milk fat percentage and milk protein percentage (P＜0.01). 【Conclusion】 The DGAT1 K232A subsitution has a great genetic effect on milking traits and could be a useful genetic marker for Chinese Holsteion breeding.

Key words: Chinese Holstein, DGAT1, milking traits, PCR-SSCP