This is a draft schedule. Presentation dates, times and locations may be subject to change.
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Administration of a Subcutaneous High Concentrate Prostaglandin F2α in Replacement Beef Heifers and the Effects on Estrus Response and Pregnancy Rates
Administration of a Subcutaneous High Concentrate Prostaglandin F2α in Replacement Beef Heifers and the Effects on Estrus Response and Pregnancy Rates
Wednesday, July 12, 2017
Exhibit Hall (Baltimore Convention Center)
To evaluate the effects of a high concentrate PGF2α (12.5 mg of dinoprost tromethamine/mL, Lutalyse HighCon, Zoetis Animal Health) compared with a conventional PGF2α (5 mg of dinoprost tromethamine/mL, Lutalyse, Zoetis Animal Health), 841 Bos taurus replacement beef heifers were assigned to treatments in a complete randomized design at 8 locations over the period of April 1 to July 15, 2016. All heifers were exposed to the 7-day CO-Synch + CIDR protocol. On d -7 of the protocol heifers received 100 µg of GnRH, and a controlled internal drug releasing (EAZI-BREED CIDR; 1.38 g of progesterone; Zoetis Animal Health) insert for 7 d. On d 0, at CIDR removal, Estrotect (Rockway Inc., Spring Valley, WI) estrus detection patches were applied to all heifers and, within location, all eligible heifers randomly received one of two PGF2α treatments: 1) CONTROL (n = 417); heifers received a 5 mL injection of conventional Lutalyse, administered i.m.; or 2) HiCON (n = 424); heifers received a 2 mL dose of Lutalyse HighCon, administered s.c. A second GnRH injection was administered 54 ± 2 h and heifers were inseminated by fixed-time AI (TAI). Heifers were evaluated for estrus activity prior to TAI. Pregnancy was diagnosed by transrectal ultrasonography between 35 and 55 d after TAI to determine the presence of a viable embryo, thereby assessing AI pregnancy rates. The percentage of heifers exhibiting estrus between CIDR removal and TAI differed (P < 0.001) among locations and ranged from 35.5 to 65.0%. The percentage of heifers exhibiting estrus between d 0 (CIDR removal) and TAI on d 2 did not differ (P = 0.677) between CONTROL and HiCON treatments (47.9 vs 49.5%). In addition, although pregnancy rates to TAI differed (P = 0.032) among locations, pregnancy rates to TAI were similar (P = 0.647) between CONTROL and HiCON treatments (46.4 vs 44.7%). Final pregnancy rates did not differ (P = 0.27) between treatments. Since the use of a high concentrate PGF2α had similar effects on estrus expression, pregnancy rates to TAI, and final pregnancy rates in beef heifers compared to conventional PGF2α, we concluded that high concentrate PGF2α is a suitable alternative for use in beef heifer estrus synchronization protocols.