title: Induction of estrus in cattle by intraovarian injection of prostaglandin F2alpha.
abstract: An effective, reduced dosage (1/10 to 1/20 the systemic dose) method for administering prostaglandin F2alpha in heifers to induce estrus is presented in this study. The PGF2alpha was injected intraovarially in five heifers at a dose of 2 mg and in another five heifers at a dose of 1 mg. Five additional heifers were injected intraovarially with 0.5 ml of distilled water and served as the controls. Regression of the corpus luteum (CL) occurred in all PGF2alpha-treated heifers resulting in marked decline of the peripheral levels of progesterone 24 h after treatment. Estrus was expressed 1 to 3 d later. Regression of the CL, estrus, and decline in the peripheral levels of progesterone were not observed in the control heifers. Conception rates in the heifers given either 2 mg and 1 mg PGF(2alpha) were 60 and 100%, respectively. Seven calves were born at the end of the normal gestation period while one calf was aborted.
authors.affiliation: Department of Theriogenology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, (060) Japan.
authors.forename: A A
authors.initials: AA
authors.lastname: Rayos
authors.forename: J A
authors.initials: JA
authors.lastname: Abalos
authors.forename: S F
authors.initials: SF
authors.lastname: Cruz
authors.forename: H
authors.initials: H
authors.lastname: Kanagawa