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United States Department of Agriculture

Agricultural Research Service

Title: Six Ways to Synchronize

Author
item GEARY, THOMAS

Submitted to: Montana Farmer
Publication Type: Popular Publication
Publication Acceptance Date: April 1, 1999
Publication Date: April 1, 1999
Citation: GEARY, T.W. SIX WAYS TO SYNCHRONIZE. MONTANA FARMER. 1999. p. WB10-11.

Interpretive Summary: This article is intended to provide an overview of the 6 most common methods of synchronizing estrus or ovulation for artificial insemination (AI) of beef cows. The simplest and least expensive method of synchronization includes one injection of prostaglandin (PGF) on the 5th day of the breeding season with heat detection and AI from day 0 to 10. Cows that are bred before day 5 do not require the PGF injection. The two-injection PGF protocol includes 2 injections of PGF 11 to 14 days apart with heat detection and breeding after either the last or both PGF injections. Cows that are bred prior to the 2nd PGF injection should not receive the 2nd injection. The MGA/PGF protocol is the most popular protocol for synchronization of estrus among heifers. It requires feeding MGA (melengestrol acetate) at a dose of .5 mg/hd/day for 14 days and an injection of PGF 17 to 19 days following the last feeding of MGA. Heifers are bred following estrus or can be time inseminated at 72 hours following the PGF injection. The Syncro-Mate-B protocol includes 9-day ear implant coupled with an injection at the time of implant insertion. Cows can be bred following an observed heat or time inseminated 48 to 54 hours following implant removal. The Select Synch and CO-Synch protocols include an injection of gonadotropin releasing hormone (GnRH) and PGF. With the Select Synch protocol, the PGF injection is given 7 days following the GnRH injection and cows are bred following an observed estrus. The CO-Synch protocol includes the injections of GnRH and PGF, but also a second injection of GnRH and timed insemination 48 hours following the PGF injection. Producers should choose a protocol based on their objectives and management styles.

Technical Abstract: This article is intended to provide an overview of the 6 most common methods of synchronizing estrus or ovulation for artificial insemination (AI) of beef cows. The simplest and least expensive method of synchronization includes one injection of prostaglandin (PGF) on the 5th day of the breeding season with heat detection and AI from day 0 to 10. Cows that are bred before day 5 do not require the PGF injection. The two-injection PGF protocol includes 2 injections of PGF 11 to 14 days apart with heat detection and breeding after either the last or both PGF injections. Cows that are bred prior to the 2nd PGF injection should not receive the 2nd injection. The MGA/PGF protocol is the most popular protocol for synchronization of estrus among heifers. It requires feeding MGA (melengestrol acetate) at a dose of .5 mg/hd/day for 14 days and an injection of PGF 17 to 19 days following the last feeding of MGA. Heifers are bred following estrus or can be time inseminated at 72 hours following the PGF injection. The Syncro-Mate-B protocol includes 9-day ear implant coupled with an injection at the time of implant insertion. Cows can be bred following an observed heat or time inseminated 48 to 54 hours following implant removal. The Select Synch and CO-Synch protocols include an injection of gonadotropin releasing hormone (GnRH) and PGF. With the Select Synch protocol, the PGF injection is given 7 days following the GnRH injection and cows are bred following an observed estrus. The CO-Synch protocol includes the injections of GnRH and PGF, but also a second injection of GnRH and timed insemination 48 hours following the PGF injection. Producers should choose a protocol based on their objectives and management styles.

Last Modified: 9/10/2014
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