Elevated progesterone concentrations enhance prostaglandin F2alpha synthesis in dairy cows

The objective was to evaluate the influence of varying plasma progesterone (P(4)) concentrations throughout the luteal phase in dairy cows on PGF(2alpha) production (assessed as plasma concentrations of 13,14-dihydro-15-keto-PGF(2alpha); PGFM) following treatment with estradiol-17beta (E(2)) or oxyt...

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Bibliographic Details
Published in:Animal reproduction science 2009-08, Vol.114 (1-3), p.62-71
Main Authors: dos Santos, Ricarda Maria, Goissis, Marcelo Demarchi, Fantini, David Augusto, Bertan, Claudia Maria, Vasconcelos, José Luiz Moraes, Binelli, Mario
Format: Article
Language:English
Subjects:
Animals
Cattle - blood
Chorionic Gonadotropin - pharmacology
Dinoprost - biosynthesis
Dinoprost - blood
Estradiol - pharmacology
Estrous Cycle
Female
Fertility Agents, Female - pharmacology
Oxytocin - pharmacology
Progesterone - blood
Time Factors
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Summary:The objective was to evaluate the influence of varying plasma progesterone (P(4)) concentrations throughout the luteal phase in dairy cows on PGF(2alpha) production (assessed as plasma concentrations of 13,14-dihydro-15-keto-PGF(2alpha); PGFM) following treatment with estradiol-17beta (E(2)) or oxytocin (OT). In all experiments, time of ovulations was synchronized with the OvSynch protocol and Day 0 corresponded to day of second GnRH injection. In Experiment 1, non-lactating dairy cows on Day 6 remained non-treated (n=9), received 20mg LH (n=7), or had ovarian follicles larger than 6mm aspirated (n=8). In Experiment 2, cows on Day 6 were untreated (n=9) or received 5000 IU hCG (n=10). In Experiments 1 and 2, all cows received 3mg E(2) on Day 17, and blood samples were collected every 30 min from 2h before to 10h after E(2). Experiment 3 was conducted in two periods, each from Days 0 to 17 of the estrous cycle. At the end of Period 1, animals switched treatments in a crossover arrangement. Animals in Group 2/8 (n=4) received 2 kg/d of concentrate in the first period and 8 kg/d in the second period. Animals in Group 8/2 (n=7) received the alternate sequence. Blood was collected daily for measurement of P(4) 4h after concentrate feeding. On Day 17, blood was collected from 1h before to 1h after a 100 IU OT injection. In Experiment 1, both plasma P(4) and release of PGF(2alpha) were similar between LH-treated and control cows (P>0.10). In Experiment 2, plasma P(4) was elevated to a greater extent on Day 17 in cows treated with hCG (P
ISSN:1873-2232
DOI:10.1016/j.anireprosci.2008.09.016