Abstract #329
Section: Physiology and Endocrinology
Session: Physiology and Endocrinology Symposium: Progesterone as an endocrine regulator of fertility in cattle
Format: Oral
Day/Time: Monday 4:45 PM–5:00 PM
Location: Sebastian L-1
Session: Physiology and Endocrinology Symposium: Progesterone as an endocrine regulator of fertility in cattle
Format: Oral
Day/Time: Monday 4:45 PM–5:00 PM
Location: Sebastian L-1
# 329
Effect of manipulating progesterone before timed artificial insemination on reproductive and endocrine parameters in Irish Holstein-Friesian dairy cows.
Paul M. Fricke*1, Paulo D. Carvalho1, Matthew C. Lucy2, Francis Curran3, Mary M. Herlihy3, Stephen T. Butler3, 1University of Wisconsin - Madison, Madison, WI, 2University of Missouri, Columbia, MO, 3Teagasc Moorepark-Animal & Grassland Research and Innovation Centre, Fermoy, Ireland.
Key Words: progesterone, timed AI, dairy cow
Effect of manipulating progesterone before timed artificial insemination on reproductive and endocrine parameters in Irish Holstein-Friesian dairy cows.
Paul M. Fricke*1, Paulo D. Carvalho1, Matthew C. Lucy2, Francis Curran3, Mary M. Herlihy3, Stephen T. Butler3, 1University of Wisconsin - Madison, Madison, WI, 2University of Missouri, Columbia, MO, 3Teagasc Moorepark-Animal & Grassland Research and Innovation Centre, Fermoy, Ireland.
Irish Holstein-Friesian dairy cows managed in a seasonal calving, grazing-based dairy system were randomly assigned to 2 treatments to manipulate progesterone (P4) before timed AI (TAI). Cows in the first treatment (High P4; n = 30) were submitted to a Double Ovsynch protocol [Pre-Ovsynch protocol (GnRH; 7 d, PGF2α; 3 d, GnRH) followed 7 d later by an Ovsynch-56 protocol (GnRH (G1); 7 d PGF2α (PGF); 24 h, PGF2α; 32 h, GnRH (G2); 16 h, TAI)]. Cows in the second treatment (n = 30; Low P4) received the same protocol with an additional PGF injection 24 h after G1. Data were analyzed using PROC MIXED and PROC GLIMMIX of SAS. Overall, synchronization rate was 92% (55/60) and did not differ between treatments. As expected, High P4 cows had more (P < 0.001) CL at PGF (1.93 ± 0.09 vs. 1.04 ± 0.04), and P4 (ng/mL) did not differ between treatments at G1 (3.8 ± 0.3 vs. 4.1 ± 0.4). Circulating P4 was greater (P < 0.001) for High vs. Low P4 cows at PGF (8.5 ± 0.9 vs. 1.6 ± 0.4) and G2 (0.30 ± 0.04 vs. 0.08 ± 0.02). Although diameter (mm) of the preovulatory follicle was greater (P < 0.001) for Low vs. High P4 cows at G2 (17.1 ± 0.4 vs. 15.6 ± 0.4), neither CL diameter nor volume differed between treatments 15 d after TAI. The proportion of pregnant cows 39 and 60 d after TAI did not differ between treatments (63%; 17/27 vs. 61%; 17/28 for Low P4 vs. High P4 cows), and no pregnancy loss occurred. Both treatment (P = 0.006) and time (P < 0.001) affected P4 concentrations in pregnant cows from 1 to 39 d after TAI with Low P4 cows having greater P4 than High P4 cows. Treatment did not affect plasma pregnancy-associated glycoprotein (PAG) concentrations for cows diagnosed pregnant 39 d after TAI; however, pregnant primiparous cows had greater (P = 0.02) PAGs from 20 to 39 d after TAI than pregnant multiparous cows. We conclude that although low P4 before TAI increased follicle growth before TAI and P4 concentrations in pregnant cows after TAI compared with high P4, low P4 before TAI did not negatively affect fertility, pregnancy loss, or PAGs after TAI in Irish Holstein-Friesian dairy cows.
Key Words: progesterone, timed AI, dairy cow
