Although the 5-day CO-Synch þ CIDR

Although the 5-day CO-Synch þ CIDR protocol
is effective, it increases the drug and labor cost and may limit adoption due to the necessity of administering
two doses of PGF [9,10] to induce luteolysis of 5 days CL. However, limiting handling number and/or frequency
should not compromise pregnancy success and added pregnancy success may justify the extra investment in
some situations. The comparison of the 5-day CO-Synch þ CIDR to two doses of PGF at CIDR removal with four handlings
versus the 7-day CO-Synch þ CIDR with three handlings in a large-scale beef operation would allow
determination of the program that will yield a better AI pregnancy rate. Based on the necessity of this comparison,
a hypothesis was developed that the 5-day CO-Synch þ CIDR protocol would improve fertility of beef cows
following TAI compared with the 7-day CO-Synch þ CIDR protocol.