Effect of MGA vs CIDR Estrus Synchronization on Estrus Response and Pregnancy Rates in 311 d Old Beef Heifers

Authors

• Hazy R. Nielson, University of Nebraska-Lincoln
• Rosemary V. Anderson, University of Nebraska-Lincoln
• Rick N. Funston Funston, University of Nebraska-LincolnFollow

Date of this Version

2016

Citation

2016 Nebraska Beef Cattle Reports

Comments

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

Abstract

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.