Abstract #T154
Section: Physiology and Endocrinology
Session: Physiology & Endocrinolog II
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Exhibit Hall B
Session: Physiology & Endocrinolog II
Format: Poster
Day/Time: Tuesday 7:30 AM–9:30 AM
Location: Exhibit Hall B
# T154
Delaying administration of prostaglandin F2α by 24 hours during a Double-Ovsynch protocol decreased fertility of lactating Holstein cows to timed artificial insemination.
A. M. Niles*1, A. E. Jones1, P. D. Carvalho1, P. M. Fricke1, 1Department of Dairy Science, University of Wisconsin-Madison, Madison, WI.
Key Words: Double-Ovsynch, PGF2α, luteal regression
Delaying administration of prostaglandin F2α by 24 hours during a Double-Ovsynch protocol decreased fertility of lactating Holstein cows to timed artificial insemination.
A. M. Niles*1, A. E. Jones1, P. D. Carvalho1, P. M. Fricke1, 1Department of Dairy Science, University of Wisconsin-Madison, Madison, WI.
To determine timing and frequency of PGF2α treatment on luteal regression, lactating Holstein cows (n = 562) were submitted to a Double-Ovsynch protocol for first timed artificial insemination [TAI; Pre-Ovsynch (GnRH; 7 d, PGF2α; 3 d, GnRH) followed 7 d later by Breeding-Ovsynch (G1; 7 d, PGF2α; 56 h, G2; 16 h, TAI)] during July and August, 2017. Cows were randomly assigned to treatments with PGF2α (dinoprost tromethamine; Zoetis) to induce luteal regression during the Breeding-Ovsynch protocol as follows: 2 25 mg PGF2α (Lutalyse Sterile Solution, 5 mg/mL) treatments on d 7 and 8 (Control; n = 182); one 25 mg PGF2α (Lutalyse HiCon, 12.5 mg/mL) treatment on d 7 (D7; n = 195); or one 25 mg PGF2α (Lutalyse HiCon) treatment on d 8 (D8; n = 185). Blood samples collected from all cows on d 7 and at G2 of the Breeding-Ovsynch protocol were assayed for progesterone (P4) by RIA. Data were analyzed by logistic regression using the GLIMMIX procedure of SAS. Overall, primiparous cows had more (P < 0.01) P/AI than multiparous cows 39 (46% vs. 23%) and 74 (42% vs. 19%) d after TAI and there was no treatment by parity interaction. D8 cows had fewer (P = 0.01) P/AI than D7 cows 39 (28% vs. 40%) and 74 (24% vs 34%) d after TAI, whereas P/AI for Control and D7 cows did not differ at 39 (35% vs. 40%, respectively) and 74 (32% vs. 34%, respectively) d after TAI. Overall, cows (n = 45) with low P4 (<1.0 ng/mL) at PGF2α had fewer (P < 0.01) P/AI 39 d after TAI than cows (n = 504) with high P4 (≥1.0 ng/mL) at PGF2α (13% vs. 36%). Among cows with high P4 at PGF2α, cows with low P4 (<0.5 ng/mL) at G2 had more (P < 0.01) P/AI 39 d after TAI than cows with high P4 (≥0.5 ng/mL) at G2 (38% vs. 17%, respectively), and more (P < 0.01) D8 cows had high P4 (≥0.5 ng/mL) at G2 (30%) than Control and D7 cows (9% and 10%, respectively). We conclude that delaying PGF2α treatment by 24 h during the Breeding-Ovsynch portion of the Double-Ovsynch protocol resulted in decreased fertility due to delayed luteal regression before TAI. Supported by USDA NIFA Hatch project 1006519
Key Words: Double-Ovsynch, PGF2α, luteal regression
