Endocrine, estrous and pregnancy response to varying dosages of Luprostiol in beef cows

• Published in: Theriogenology Vol. 31; no. 4; pp. 801 - 812
• Main Authors: Plata, N.I., Spitzer, J.C., Henricks, D.M., Thompson, C.E., Plyler, B.B., Newby, T.J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.1989
• Subjects: cattle; fertility; luprostiol; synchronization; luprostiol; synchronization; cattle; fertility
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/0093-691X(89)90025-3

Multiparous lactating beef cows were observed for estrus and randomly assigned to one of four Luprostiol (13, thia-PG-F 2α analog) treatment groups receiving 3.8 (LI), 7.5 (LII), 15 (LIII) or 30 (LIV) mg Luprostiol, respectively, or to an untreated control group (C), or to a positive control group (E) receiving 500 mcg Estrumate. Cows received their respective treatments in a single dosage on Day 7, 8 or 9 of the estrous cycle (estrus = Day 0) and were artificially inseminated 12 h following the subsequent estrus. Blood samples were collected from all groups immediately prior to treatment and at 12-h intervals to 48 h post treatment and analyzed for progesterone (P 4). Blood samples were collected at 3-h intervals from 24 to 72 h post treatment for animals in Group LIII and for 48 h (or observed estrus) starting on Day 19 of the estrous cycle for animals in Group C. These samples were analyzed for estradiol-17β(E 2), follicle stimulating hormone (FSH) and luteinizing hormone (LH). Treatment with Luprostiol at doses ≥ 7.5 mg resulted in a synchronous estrous response during the first 5 d post treatment in 75 to 95% of cows treated. Luteal function, as evaluated by systemic P 4 concentration, paralleled results observed for estrous response. Treatment with a 15 or 30 mg dose of Luprostiol resulted in greater overall pregnancy rate at synchronized estrus. No biologically significant differences were found in blood levels of E 2, FSH or LH around the time of estrus between cows in Groups C and LIII. Results from these studies indicate treatment with Luprostiol at doses ≥ 7.5 mg resulted in a synchronous estrus during the first 5 d after treatment. Pregnancy rates and endocrine changes were similar to those observed in control and Estrumate-treated cows.