title: Effect of two low doses of prostaglandin F2αon luteolysis in dairy cows.
abstract: In this preliminary study, we determined the effect of a modified method involving the administration of two low doses of prostaglandin F2α(PGF2α) at an interval of 24 h on luteolysis in dairy cows, and compared it with the standard single-dose method. Twenty-six cows were assigned to three groups treated with two low doses (TLD group, n = 10), one standard dose (SD group, n = 10), and one low dose (OLD group, n = 6) on day 9 to 10 of the oestrous cycle (day 0 = the day of PGF2αadministration). Their serum progesterone (P4) levels and corpus luteum (CL) sizes were measured daily from day 0 to 4 to assess CL regression. The results indicated that the proportion of complete luteolysis, indicating a P4 value ≤ 1 ng/mL on day 3, was higher in the TLD group (100.0%) than in the SD (60.0%) and OLD (66.7%) groups. Ultrasonically detected changes in the CL area correlated with the shifts in the P4 values in both the TLD and the SD groups. The remaining CL area was significantly smaller in the TLD group (17.8% ± 3.3%) than in the SD or OLD group on day 4. Thus, we concluded that the proportion of luteolysis in cows was increased with two low doses of PGF2αas compared to a single PGF2αdose, indicating the necessity of the second dose of PGF2α. However, further studies with larger sample sizes in the field are required.
authors.affiliation: Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University , No. 145, Xingda Road, South District, Taichung City 40227, , Taiwan (R. O. C.).
authors.forename: Tsung-Ching
authors.initials: TC
authors.lastname: Liu
authors.affiliation: Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University , No. 145, Xingda Road, South District, Taichung City 40227, , Taiwan (R. O. C.).
authors.forename: Chia-Yu
authors.initials: CY
authors.lastname: Ho
authors.affiliation: Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University , No. 145, Xingda Road, South District, Taichung City 40227, , Taiwan (R. O. C.).
authors.forename: Jacky Peng-Wen
authors.initials: JP
authors.lastname: Chan
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D015237:Dinoprost / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D003341:Luteolysis / Q000187:drug effects*; D010060:Ovulation / Q000378:metabolism; D011374:Progesterone / Q000097:blood / Q000378:metabolism
chemical_list: D011374:Progesterone; D015237:Dinoprost
keywords: PGF2α; dairy cows; luteolysis; standard dose; two low doses