Induction of parturitionin cattle with prostaglandin F2α

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Induced parturition by the use of prostaglandin F2α (PGF2α) was investigated in cattle. Thirteen animals including 3 cows at 116159 days of gestation (group A), 3 cows and 2 heifers at 252258 days of gestation (group B), and 2 cows and 3 heifers at 272276 days of gestation (group C), received either an intrauterine injection with PGF2α dissolved in saline, or an intramuscular injection with PGF2α suspended in propylene glycol. Estriol, each daily dose of 50 mg, was injected intramuscularly 1 to 3 times between one day before and one day after PGF2α treatment in 7 animals. Concentration of progesterone in blood plasma collected from jugular vein following the treatment was determined in 4 animals, by a radioimmunoassary method. In group A, a total amount of 25 mg PGF2α was infused in 3 times into the slit between the endometrium and fetal membrane of the gravid uterine horn at 6-hour intervals. One of them was given an additional 10 mg PGF2α, 21 hours later. Abortion was induced in all cows 51, 79, and 91 hours after the first PGF2α infusion, respectively. In group B, 2 cows and 2 heifers received 3 intrauterine infusions with a total amount of 2030 mg PGF2α, at 912-hour intervals. Two of them were given an additional 10 mg PGF2α, 26 and 31 hours later, respectively. Parturition in 2 animals given the additional treatment was induced 91 and 108 hours after the first treatment, and in 2 other animals 39 and 58 hours, respectively. In the remaining one heifer which was injected intramuscularly with 10 mg PGF2α, and an additional 10 mg, 69 hours later, parturition was induced 118 hours after the treatment. In group C, 2 heifers received a single intramuscular injection with 10 mg PGF2α, and an another heifer and a cow were injected intramuscularly with a total amount of 15 mg PGF2αdivided at 3-hour interval. The remaining one cow received 2 intrauterine infusions with a total amount of 20 mg PGF2α, at 12-hour interval. Parturition was induced in all animals between 2953 hours after the treatment. It is considered that the shorter the interval between the treatment and the expected calving date, the easier is the induction of parturition. In one of 5 animals in group B, and 3 of 5 animals in group C, dystocia in more or less extent was observed. However, all of the calves were alive when they were born. Fetal placentae were retained for 26 days in all animals in groups B and C. Progesterone levels in peripheral blood plasma dropped sharply following the PGF2α injection, from 3.55.3 ng/ml prior to the treatment to 1.32.0 ng/ml at the time of 612 hours after the treatment. When the plasma progesterone levels had maintained as low as 1 ng/ml or less for some time, the cervical canal dilated completely as large as five fingers width. These results indicated that the essential role of PGF2α in the induced parturition should be its luteolytic action.
日本繁殖生物学会の論文

Induction of parturitionin cattle with prostaglandin F<SUB><SUB>2α</SUB></SUB>

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日本繁殖生物学会 | 論文

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