| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 98 === Marker-assisted selection in dairy cattle, some genes are proposed as potential candidates associated with dairy cow performance. In the present study, the growth hormone receptor (GHR) and prolactin precursor (PRL) genes were selected to detect the genotypic and allelic frequencies. The genotypes associated with milk and milk fat yields and percentage of protein and milk fat were investigated. The blood samples and milk production records of Holstein-Friesian cows were collected from the local farms in Tainan county and National Chiayi University in Taiwan for this study. PCR-RFLP genotyping method was used for genotyping. The results showed that the AA genotype frequency (0.695) of GHR gene was higher than that of AG genotype (0.295) and GG genotype (0.010) in the tested population of Holstein cows and frequencies of allele A and G were 0.842 and 0.158, respectively. The GG genotype frequency (0.739) of PRL gene was higher than that of AG genotype (0.261), but the AA genotype was not found in the tested animals and frequencies of allele G and A were 0.870 and 0.130, respectively. The values of milk and fat yields of AA and AG types of GHR gene seems higher than GG type of tested animals, but no significant differences (p > 0.05) between other traits with the genotypes of both genes were found in this study.
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