Effects of administration of prostaglandin F<sub>2α</sub> (PGF) at initiation of the 7-day CO-Synch+CIDR estrus synchronization protocol for suckled beef cows

Mercadante, V.

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Effects of administration of prostaglandin F_2α (PGF) at initiation of the 7-day CO-Synch+CIDR estrus synchronization protocol for suckled beef cows

Thursday, July 24, 2014: 9:00 AM

2505B (Kansas City Convention Center)

V. R.G. Mercadante , University of Florida, Marianna, FL

L. E. Kozicki , Pontifical Catholic University (PUCPR), Curitiba, Brazil

F. M. Ciriaco , University of Florida, Marianna, FL

D. D. Henry , University of Florida, Marianna, FL

C. R. Dahlen , North Dakota State University, Fargo, ND

J. E. Larson , Mississippi State University, Mississippi State, MS

B. E. Voelz , Mississippi State University, Mississippi State, MS

D. J. Patterson , University of Missouri, Columbia, MO

G. A. Perry , South Dakota State University, Brookings, SD

T. L. Steckler , University of Illinois, Simpson, IL

J. S. Stevenson , Kansas State University, Manhattan, KS

G. C. Lamb , University of Florida, Marianna, FL

Recorded Presentation (mp4)

Abstract Text:

We determined the effect of administration of PGF at CIDR insertion during the 7-day CO-Synch+CIDR estrus synchronization protocol on subsequent pregnancy rates of suckled beef cows. At 13 locations, cows were ovulation synchronized with the 7-day CO-Synch+CIDR protocol (100 μg injection of GnRH at CIDR insertion [d -10] with 25 mg injection of PGF at CIDR removal [d -3], followed by an injection of GnRH and fixed-time AI (TAI) on d 0). Cows were stratified by days postpartum, BCS, and parity and assigned to 1 of 2 treatments: CO-Synch+CIDR (n = 819) and PG-CO-Synch+CIDR (a 25 mg injection of PGF was administered at CIDR insertion of the CO-Synch+CIDR protocol; n = 827). Follicle dynamics and corpus luteum development were assessed on d -10 and -3 and pregnancy status determined on d 30-35. Blood was collected on d -20, -10, -3, and 0 to determine progesterone (P4). Overall fixed-time artificial insemination (TAI) pregnancy rates (53.5 ± 1.9% and 50.4 ± 1.9%, for CO-Synch+CIDR and PG-CO-Synch+CIDR, respectively) did not differ (P = 0.802) between treatments. A location effect (P < 0.001) existed with pregnancy rates being the greatest at the KS2 location (67.2 ± 6.1%) and the poorest at the KS4 location (15.3 ± 5.3%). Of the 1,217 cows in which cyclic status was assessed, 55% were determined to be cyclic; however, incidence of pregnancy was not associated with cyclic status or the treatment x cyclic status interaction. Concentrations of P4 were greater (P < 0.001) for CO-Synch+CIDR (4.1 ± 0.3 ng/mL) than PG-CO-Synch+CIDR (3.4 ± 0.3 ng/mL) on d -3 whereas diameter of largest follicle on d -3 tended (P= 0.094) to be greater for PG-CO-Synch+CIDR (13.4 ± 0.3 mm) than CO-Synch+CIDR (12.6 ± 0.3 mm). We concluded that administration of PGF at CIDR insertion of the CO-Synch+CIDR protocol failed to increase TAI pregnancy rates in suckled beef cows, but at CIDR removal, decreased concentrations of P4 and tended to increase dominant follicle diameter.

Keywords: Ovulation Synchronization, Artificial Insemination, Beef Cow

538 Effects of administration of prostaglandin F2α (PGF) at initiation of the 7-day CO-Synch+CIDR estrus synchronization protocol for suckled beef cows

538
Effects of administration of prostaglandin F_2α (PGF) at initiation of the 7-day CO-Synch+CIDR estrus synchronization protocol for suckled beef cows