Animal Science, Department of


Date of this Version



2016 Nebraska Beef Cattle Reports


© The Board Regents of the University of Nebraska. All rights reserved.


A study compared the effect of melengestrol acetate (MGA)-prostaglandin (PG) and 14- day controlled internal drug release (CIDR)- PG estrus synchronization protocols on estrus response and pregnancy rates of 311 d old heifers (n = 153). Pre-breeding BW was 50.1% of predicted mature BW. Percentage of heifers demonstrating signs of estrus was similar between synchronization treatments (CIDR vs MGA, 71.5 vs 77.4 ± 1.0%). Pregnancy rates to AI of heifers expressing estrus (n = 115) and final pregnancy rate were similar between CIDR and MGA synchronization treatments. Approximately half of these 311 d old heifers exposed to AI and bulls became pregnant.

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