台灣荷蘭種乳牛GHR與PRL基因單核苷酸多態性之研究

Abstract

在乳牛基因標記輔助選拔的研究中，有些基因是被認為是與乳牛產乳性狀有關之潛在候選基因。本試驗自台南地區與嘉義大學所飼養之荷蘭種乳牛採集血樣及收集產乳紀錄，分析潛在候選基因中之生長激素受（growth hormone receptor , GHR）和泌乳素前質（prolactin precursor , PRL）基因之基因型和交替基因基因頻率，同時也探討基因型與乳中蛋白質、脂肪百分比及牛奶脂肪量、乳產量間之相關性。基因型之測定是應用 PCR–RFLP的方法為之。試驗結果顯示，在測試的荷蘭種乳牛中，GHR基因之AA基因型頻率（0.695）高於 AG基因型（0.295）和GG基因型（0.010）者。 交替基因A和G的頻率分別為0.842和0.158。PRL基因之 GG基因型頻率（0.739）高於 AG基因型（0.261）者，但在供試的荷蘭種乳牛中沒有發現AA基因型者。其交替基因G和A的頻率分別為0.870和0.130。從數值觀之，GHR基因中，基因型為AA和AG之個體，其乳量與脂肪的產量均似乎高於GG基因型者。惟就供試動物之其他性狀而言，性狀之表現並不因基因型之不同而有顯著差異（p > 0.05），兩個基因皆然。

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.