title: Effects of gonadotropin-releasing hormone administration or a controlled internal drug-releasing insert after timed artificial insemination on pregnancy rates of dairy cows.
abstract: This study investigated the effects of gonadotrophin-releasing hormone (GnRH) administration (Experiment 1) and a controlled internal drug-releasing (CIDR) insert (Experiment 2) after timed artificial insemination (TAI) on the pregnancy rates of dairy cows. In Experiment 1, 569 dairy cows that underwent TAI (day 0) following short-term synchronization with prostaglandin F2αwere randomly allocated into two groups: no further treatment (control, n = 307) or injection of 100 µg of gonadorelin on day 5 (GnRH, n = 262). In Experiment 2, 279 dairy cows that underwent TAI (day 0) following Ovsynch were randomly allocated into two groups: no further treatment (control, n = 140) or CIDR insert treatment from days 3.5 to 18 (CIDR, n = 139). The probability of pregnancy following TAI did not differ between the GnRH (34.4%) and control (31.6%,p> 0.05) groups. However, the probability of pregnancy following TAI was higher (odds ratio: 1.74,p< 0.05) in the CIDR group (51.1%) than in the control group (39.3%). Overall, CIDR insert treatment at days 3.5 to 18 increased pregnancy rates relative to non-treated controls, whereas a single GnRH administration on day 5 did not affect the pregnancy outcomes of dairy cows.
authors.affiliation: Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea.
authors.forename: Jae Kwan
authors.initials: JK
authors.lastname: Jeong
authors.affiliation: Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea.
authors.forename: In Soo
authors.initials: IS
authors.lastname: Choi
authors.affiliation: Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea.
authors.forename: Hyun Gu
authors.initials: HG
authors.lastname: Kang
authors.affiliation: National Institute of Animal Science, RDA, Cheonan 31000, Korea.
authors.forename: Tai Young
authors.initials: TY
authors.lastname: Hur
authors.affiliation: Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea.
authors.forename: Ill Hwa
authors.initials: IH
authors.lastname: Kim
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003008:Cloprostenol / Q000494:pharmacology*; D003270:Contraceptive Agents / Q000008:administration & dosage; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007315:Insemination, Artificial / Q000662:veterinary; D008186:Luteolytic Agents / Q000494:pharmacology*; D011247:Pregnancy; D018873:Pregnancy Rate; D012098:Reproduction / Q000187:drug effects
chemical_list: D003270:Contraceptive Agents; D008186:Luteolytic Agents; C074283:estradiol 3-benzoate; D007987:Gonadotropin-Releasing Hormone; D003008:Cloprostenol; D004958:Estradiol
keywords: dairy cow; post-insemination; pregnancy rate; progesterone concentration