Maintenance of Pregnancy in Ovariectomized Cattle with Progestin Compounds and Their Effect on Progestin Levels in the Corpus Luteum,

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Abstract
Pregnancy was maintained following ovariectomy after 88 days with daily injections of 125 mg of Delalutin (17-alpha-hydroxyprogesterone-17-n-caproate) when the treatment was started at least 8 days before surgery. Daily injections of 50mg of repositol progesterone beginning 0-12 days before ovariectomy maintained pregnancy after the 66th day. Smaller daily injections of either repositol progesterone or Delalutin were more satisfactory in maintaining pregnancy than larger, less frequent injections. Neither repositol progesterone nor Delalutin maintained pregnancy when 500 mg were injected weekly. When exogenous progesterone was withdrawn more than 6 days before parturition (expected at 279 days) the placentae were retained in all cases and were very difficult to remove 48 to 60 hours later. Total progesterone and its concentration in the corpus luteum was significantly increased (P<0.005) by administering progestins one to 12 days before ovariectomy. [DELTA]4-Pregnene-20-[beta]-ol-3-one was unaffected, being slightly higher in the untreated cows. There was also a consistent increase in progesterone concentration in the ovaries minus the corpus luteum for the treated cows, as compared with untreated cows (P<0.10).