PSV-A-1 Estrus Response and Pregnancy Rates of Beef Cows Enrolled in two Fixed-Time Artificial Insemination Protocols, with or without pre-Synchronization

Abstract Pre-synchronization strategies with prolonged exposure to exogenous progesterone have the potential alter estrus expression and improve fertility in beef cows. The objective of this study was evaluate response pregnancy rate suckled cows enrolled two fixed-time artificial insemination (TAI) protocols. A total 1,216 (angus-crossed) at 10 locations across VA were study. Within location, ranked by body weight, days postpartum randomly assigned one treatments: 1) 7&7 (n = 610), administered prostaglandin F2α (PGF; 25 mg) a controlled internal drug releasing (CIDR) insert [Day -14], an injection GnRH (100 μg -7]), PGF CIDR removal 0], second concurrently TAI 64 ± 2 h later 2]; 2) 7-day CO-Synch+CIDR (7-day; n 606), μg) -7], (25 2]. All received alert patch (ESTROTECT) on Day 0 evaluated for activation 2. Pregnancy diagnosed transrectal ultrasonography between 45 65 after TAI. percentage exhibiting greater (P < 0.001) compared (72.8% 55.9%, respectively). However, similar 0.328) treatments (63.8% 61.1%, 7-day, We conclude that protocol had increased expression, but when protocol.