Effects of synthetic LH-RH on ovulation in the cow

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  • YAMAUCHI Makoto
    Department of Veteri-nary Surgery and Obstetrics, Faculty of Agricul-ture, University of Tokyo Nippon Veterinary and Zoote-chnical College, Musashino-shi
  • KARIYA Takayoshi
    Department of Veteri-nary Surgery and Obstetrics, Faculty of Agricul-ture, University of Tokyo National Institute of Animal Industry
  • TANAKA Mikio
    Department of Veteri-nary Surgery and Obstetrics, Faculty of Agricul-ture, University of Tokyo
  • SASAKI Nobuo
    Department of Veteri-nary Surgery and Obstetrics, Faculty of Agricul-ture, University of Tokyo

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Other Title
  • 合成ＬＨ‐ＲＨによる牛の排卵誘起に関する研究　Ｉ　　分べん後の排卵誘起及び排卵障害の治療
  • ゴウセイ LH RH ニヨル ウシ ノ ハイラン ユウキ ニカンスルケンキュウ
  • 1. 分娩後の排卵誘起及び排卵障害の治療

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Abstract

1. Twenty dairy cows with quiescent ovaries were given synthetic LH-RH analog for inducing ovulation at 1253 days (av. 26.1 days) postpartum. Intramuscular injections with 200 μg and 100 μg LH-RH at about 90 minutes interval were performed in these cows except 2 animals in which 2000 μg of LH-RH were administered by single intramuscular injection. Ovulation was induced 723 days (14.9±4.8 (SD) days) after the treatment in 15 (75.0%) of 20 cows. The ovulation was preceded by estrus in these cows except 1 animal of silent ovulation. Eight (66.7%) of 12 cows which were served by 12 inseminations during the induced estrus became pregnant (Table 1). Mean days from the last calving to the 1st ovulation for 10 cows treated with LH-RH (treatment period: 40.4±11.5 (SD) days) were significantly shorter (P<0.05) than those from former calving to the 1st estrus for the same cows (control period: 104.2±78.1 (SD) days) (Table 2). From these results it seems that LH-RH is effective to induce estrus and ovulation in postpartum dairy cows.<BR>2. Eleven dairy cows, exhibiting estrus for 23 days, diagnosed as delayed ovulation or un-ovulation were treated with a single intramuscular injection of 100300 μg LH-RH. The treatment was followed by artificial insemination in 10 cows. Ovulation was induced within 12 days after the injection in all of the treated animals. Five cows (50.0%) conceived after the 1st insemination and 2 cows became pregnant by the 2nd insemination performed during the next untreated estrous period (Table 3). Ovarian responses to LH-RH in 2 cases of unovulation are shown in Fig. 1. The results indicate that LH-RH is effective to treat ovulation failure in dairy cows.

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