福岡県農業総合試験場研究報告

ウシ初期胚の発育ステージおよび採取部位別の性判定率と凍結条件の違いによる受胎率

［摘要］黒毛和種およびホルスタイン種から過排卵処理によって採取した体内受精胚の10～ 20%の部分を切断採取後，XYセレクターを用いた PCR法によって性判定し，切断後残ったバイオプシー胚を 3～ 4時間あるいは20～24時間培養した。後期桑実胚から胚盤胞期胚までの発育ステージにおいて，性判定率は85.5～ 94.4%，発育率は97.8～100%であり発育ステージの違いによる差はなかった。胚の採取部位別の判定率は，正常細胞の 92.6%に対して，変性細胞は91.7%と差はなく，培養後の発育率も各々 95.1%， 95.8%と差がなかった。凍結液のエチレングリコール濃度において，1.5Mの受胎率（6.7%）は1.8M（25.0%）と差がなかったが，新鮮胚の受胎率（50.0%）に対して有意に低率であった。また，凍結前の培養時間において，20～24時間の受胎率（21.4%）は3～4時間（34.6%）と差がなかったが，新鮮胚（48.5%）に比べて有意に低率であった。PCR法による胚の性判定および移植実証試験として，延べ14頭の高能力乳牛から採取した胚を性判定した結果，性判定率は94.7%，新鮮胚移植による受胎率は54.5%と良好であった。

Effects of Bovine Embryo Stages and Biopsied Parts on the Judgment Rate of Sex Determination and Effect of Freezing Conditions on Pregnancy Rates after Transfer. Shuji UEDA, Miyuki MORI and Shojiro KASA (Fukuoka Agricultural Research Center, Chikushino, Fukuoka 818-8549, Japan) Bull. Fukuoka Agric. Res. Cent. 21 : 49 - 52 (2002)

　Day 7 embryos collected from superovulated donors were biopsied using a microblade with a micromanipulator. To determine the sex of embryos,　samples(10-20%) of embryos were diagnosed using the PCR(Polymerase Chain Reaction) method. The biopsied embryos were cultured for 3-4 or 20-24 hours. The judgement rates of sex determination　among late morulae and blastocysts were 85.5-94.4% and the survival rates after culture were 97.8-100%.For the both rates, the stage of embryos showed no significant effects. The judgement rate using a few normal cells and abnormal cells from an embryo were 92.6% and 91.7%, respectively, with no significant difference between embryos stages. The pregnancy rates of biopsied embryo frozen in 1.5M EG and 1.8M EG after culture for 20-24 hour were 6.7% and 25.0%, respectively. The former was lower than the pregnancy rate(50.0%) of fresh biopsied embryos(p<0.05). The survival rates of biopsied embryos cultured for 3-4 hours and 20-24 hours before freezing in 1.8M EG were 34.6% and 21.4%, respectively. The latter was lower than the pregnancy rate (48.5%) of fresh biopsied embryos(p<0.05).

　The sex of embryos collected from superovulated high-producing dairy cows were determined, and then 33 biopsied embryos were transferred recipients for fresh embryos. The success rate of sex determination was 94.7%(72/76); the pregnancy rate was 54.5%(18/33).