Is GnRH necessary at CIDR insertion using a 7-Day CIDR synchronization protocol for beef heifers?

David M. Grieger,D.R. Eborn,E.E. Blair

doi:10.4148/2378-5977.2897

Abstract

The EAZI-BREED CIDR is commonly used in estrous synchronization protocols for both beef heifers and cows. The label calls for insertion of a progesterone-impregnated controlled internal drug release (CIDR) for 7 consecutive days with an injection of prostaglandin F2αgiven a day before CIDR removal. Animals should display estrus 1 to 3 days after CIDR removal. Modifications to this protocol include administration of gonadotropin-releasing hormone (GnRH) at the time of CIDR insertion and administration of the prostaglandin injection at the time of CIDR removal on day 7. Use of GnRH in conjunction with a CIDR may improve estrous synchronization in beef cows and fertility at fixed-time insemination but may not be necessary when synchronizing beef heifers. Our objective was to compare heat response and fertility in heifers with or without GnRH administration at the time of CIDR insertion. Our hypothesis was that heifer fertility would be similar between treatments.

Highlights

The EAZI-BREED controlled internal drug release (CIDR) is commonly used in estrous synchronization protocols for both beef heifers and cows
The label calls for insertion of a progesterone-impregnated controlled internal drug release (CIDR) for 7 consecutive days with an injection of prostaglandin F2α given a day before CIDR removal
Interval from CIDR removal to onset of estrus was similar between treatments with more than 85% displaying estrus from 48 to 72 hours after the prostaglandin F2α injection

Summary

Part of the Other Animal Sciences Commons

Recommended Citation Eborn, D.R.; Blair, E.E.; and Grieger, David M. (2011) "Is GnRH necessary at CIDR insertion using a 7-Day CIDR synchronization protocol for beef heifers?," Kansas Agricultural Experiment Station Research Reports: Vol 0: Iss. 1.

Introduction

Experimental Procedures

Results and Discussion