title: Response of dairy heifers to Prostaglandin F2alpha after treatment with human chorionic gonadotropin.
abstract: After the observation of estrus following administration of Prostaglandin F2alpha (PGF2alpha), 79 dairy heifers were randomly either injected with 2500 IU of human chorionic gonadotropin (hCG) 48 h postestrus or maintained as controls with no injection at that time. Five to 9 d later, after a blood sample for progesterone determination was taken, all heifers were injected with 25 mg of PGF2alpha. Heifers observed in estrus within the next 5 d were inseminated about 12 h after initial observation and were palpated for pregnancy 45 to 60 d postinsemination. Heifers treated with hCG had higher progesterone concentrations, reduced and delayed estrual responses, and lower insemination fertility rates when compared with control heifers.
authors.affiliation: Department of Dairy Science, Mississippi State University, Mississippi State, MS 39762, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Shipley
authors.forename: J W
authors.initials: JW
authors.lastname: Fuquay
authors.forename: A E
authors.initials: AE
authors.lastname: Smith
authors.forename: M J
authors.initials: MJ
authors.lastname: Stuart