Abstract: The PCR-SSCP polymorphism of POU1F1 gene exon 6, GHRgene exon10, GHRH-R gene exon 2 and CSN1S2 gene exon 18 were studied in 93 hybrid dairy cattles improved by crossbreeding with Holstein frozen sperm. The results showed that in four examined genes locus, only the POU1Fl gene exon 6 have two genotypes, the genotypic frequencies of AB and BB were 0.0323 and 0.9677 respectively; the allelic frequencies of A and B were 0.0162 and 0.9838, and the individual with genotype AA has not discovered. The population was at Hardy-Weinberg equilibrium at this locus. The gene heterozygosity and polymorphism information content were 0.0318 and 0.0313 respectively. The sequencing result showed that comparing with Y15995 of POU1Fl gene sequence in general yellow cattle, the A allele had happened base transversion of G-C at the 209th bp of POU1Fl gene exon 6 which caused a amino acid substitute of Thr to Arg, and the reasons and effects of this polymorphism need to study futurely.

Key words: dairy cattle; gene; PCR-SSCP; polymorphism