Abstract: 【Objective】The objective of this study was to study the polymorphism of AGPAT6 gene and relationship between the polymorphisms and the milk performance of dairy cattle.【Method】 PCR-RFLPs method was used for identification polymorphism in cloned the 2nd intron of AGPAT6 (1-acyl-sn-glycerol-3-phosphate acyltransferase zeta). Genotypic effects of the 2nd intron of AGPAT6 on milk yield, milk fat percentage, milk protein percentage, milk dry material and somatic cell score(SCS) were analyzed. 【Result】A PstI-RFLPs and a BanI-RFLPs were detected in the 2nd intron of AGPAT6. The PstI-RFLPs and BanI-RFLPs were common in all the detected breeds(lines). The PstI-RFLPs and BanI-RFLPs were significant relation with average milk fat percentage of Holstein(P < 0.05). Individuals with genotype BB had higher milk fat percentage. The PstI-RFLPs was significant relation with SCS of Holstein(P < 0.05), and individuals bearing AA genotype had higher ( P < 0.05) SCS. The BanI -RFLPs was significant relation with 305-days matured equivalency of Holstein(P < 0.05), and individuals with genotype AA had higher ( P < 0.05) milk yield. The PstI-RFLPs was significant relation with average milk fat percentage and average dry material of Long-Zhou Cow(P < 0.05), but no significant associations were founded between BanI –RFLPs and milk production traits in Long -Zhou Cow. 【Conclusion】The B allele of PstI-RFLPs was favorable allele of milk fat percentage, SCS for Holstein and milk dry material for Long -Zhou Cow. The B allele of BanI -RFLPs was favorable allele of milk fat percentage and the A allele of BanI -RFLPs was favorable allele of 305-days matured equivalency for Holstein.

Key words: AGPAT6 Gene, Dairy Cattle, Milk Production Traits