Animal Science, Department of


Date of this Version



2014 Nebraska Beef Cattle Report, UNL Extension MP99, pp. 8-10.


Copyright © 2014 University of Nebraska.


Yearling Angus heifers at a commercial ranch in the Nebraska Sandhills were randomly assigned to one of two progestin-based fixed-time AI protocols (MGA or 14-day CIDR) to compare pregnancy rates. Heifers had similar fixed-time AI pregnancy rates between MGA and 14-day CIDR. A similar proportion of MGA and 14-day CIDR heifers displayed a second estrus; however, heifers previously synchronized with MGA tended to have a greater second AI pregnancy rate. Overall pregnancy rate was similar between MGA and 14-day CIDR treatments. The MGA system was the more cost effective synchronization protocol in this study.