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台灣荷蘭牛雙胎率與freemartin DNA檢測

林德育 楊德威 黃鈺嘉 陳若菁 吳明哲

行政院農業委員會畜產試驗所

為探討台灣乳牛的雙胞胎率及驗證雄相雌性體 (freemartin) DNA 檢測法，分析行政院農業委員會畜產試驗所自1987年至2003年乳牛分娩記錄，共計1284胎。其中雙胞胎率為2.9% (37/1284)，異性雙胞胎率為1.3% (17/1284)。異性雙胞胎的女牛於1 歲齡左右以直腸觸診其生殖器官是否正常，在17頭異性雙胞胎的女牛有1 頭為正常個體 (5.9%)，該女牛經配種後，並順利產下正常仔牛。以牛性別標記AMX/Y檢測該牛隻，結果證實該已產仔之雙胞胎母牛為雌性基因型。進一步，應用南部一家種牛場3胎異性雙胞胎仔牛血樣DNA，仔女牛則皆帶有雄性基因型，這些仔女牛判定為雄相雌性體。本試驗證明荷蘭乳牛雙胎率達 2.5%以上。以牛性別標記AMX/Y鑑別女牛是否為雄相雌性體，為一簡易可靠的DNA分生檢測方法，檢測結果可提供酪農作為選留異性雙胞胎仔女牛依據。

關鍵語：牛、雄相雌性體、遺傳標記。

TWINING RATE OF TAIWAN HOLSTEINS AND DNA
FREEMARTIN DIAGNOSIS

D. Y. Lin, T. W. Yang, Y. C. Huang, J. C. Chen and M. C. Wu

Livestock Research Institute, Council of Agriculture

The objective of this study was to investigate the frequency of twinning rate of Taiwan Holsteins and to test the reliability of DNA freemartin diagnosis. A total of 1284 reproductive records of cows at Livestock Research Institute, Council of Agriculture from 1987 to 2003 were analyzed. The twinning rate were 2.9% (37/1284) and heterozygous twinning rate was 1.3% (17/1284). Rectal palpation diagnosed freemartins held around one year old for the heterozygous twins. Only one heifer was normal in these 17 heterozygous twins. Tracing breeding records, the “normal heifer” grew up as a normal cow and gave a calf at last. There were four set blood samples applied for the reliability of DNA test, including the “normal heifers’ samples” and three other heterozygous twins from a southern dairy farm of Taiwan. AMX/Y was the selected as sexing genetic marker to identify genotypes of these animals. Test Results proved that the genotype of the “normal heifer” was a normal female, but other three heterozygous twins all had male genotypes. Results from this study indicated twining rate of Taiwan Holsteins was higher than 2.5% and DNA trials supported AMX/Y genetic marker was a simple and easy technique for diagnosis of freemartin in dairy cattle.

Key Words: Cattle, Freemartin, Genetic marker.