The Beef Reproduction Task Force composed of representatives of the AI and pharmaceutical companies, veterinarians and reproduction specialists have developed based on research data and field use a list of recommended synchronization protocols for use in cows in 2015. The protocols can be found in the AI catalogs and on the Beef Reproduction Task Force website.
Recommended Protocols & Useful Tools
Take note that not all protocols are for both cows and heifers. There is a difference in physiological response between heifers and cows. It is important that you use a cow protocol. Likewise, follow the protocol, give the proper hormone injection or insert at the right time and don’t expect to jump-start all cows that are not cycling. To help increase the success of the synchronization protocol cows need to be at a body condition score of 5 or better during breeding season and be at least 50 days post calving. If there are young, thin and or late calving cows in the herd, it is likely they are not cycling. The addition of a progestin such as CIDR® in the protocol can help jump-start some of these non-cycling cows. However, caution needs to be taken, CIDR® or other progestins are not the “cure all” for thin, young and late calving cows. Consideration needs to be taken whether it is cost effective to synchronize these cows. An evaluation of the nutrition program is recommended if a high percentage of cows are not cycling.
It is tempting to give a cow an injection in the rump, because there is the belief that cull cows solely end as hamburger beef. However, a majority of the “middle meats” such as ribeye rolls, short-loins, strip-loins, along with round are marketed as such. Therefore, Beef Quality Assurance guidelines should be followed when giving all injectable hormones. Secondly, giving the injection in the rump does not increase the efficacy or speed of the hormone because it was administered “closer to the ovary”. All drugs must enter the blood system and travel to the heart and lungs before reaching the target organ (i.e. ovaries).
When handling all hormones including CIDR® wear latex or non-latex gloves regardless if you are a man or a woman. Example, prostaglandin is a smooth muscle contractor, our intestines are the largest smooth muscle in the human body. If prostaglandin is absorbed through the skin it can “tie up” the digestive system. Additionally, the hormones function in the human body like it does in a heifer therefore, extreme care should be taken when handling all synchronization hormones.
The recommended cow estrous synchronization protocols have been put into one of three categories:
- Heat Detection Protocol
- Heat Detection and Timed AI Protocol
- Fixed Time AI Protocol
1. Heat Detection Protocols: Cows in these protocols should be inseminated 6 to 12 hours after the first observation of standing heat. During peak heat activity which is approximately 48 to 72 hours after prostaglandin; heat detection should occur at a minimum of 3 times per day for at least 1 hour per check for a total of 3 hours with 5 to 6 hours of heat detection being better. Refer to the SDSU Extension publication Detection of Standing Estrus In Cattle for more information on detecting heat. The heat detection protocols for cows include:
- Select Synch
- Select Synch + CIDR®
- PG 6-day CIDR®
2. Heat Detect and Time AI (TAI) Protocols: These protocols include a combination of both heat detection and timed insemination. Cows observed in heat should be inseminated 6 to 12 hours after standing heat. After approximately 3 days of heat detection, all cows not showing heat after PG injection will be given an injection of GnRH and inseminated (i.e. timed insemination). The amount of time spent on heat detection is reduced and early responders have a better chance of conceiving compared to a single fixed-time AI. The Heat Detect and Timed AI protocols include:
- Select Synch & TAI
- Select Synch + CIDR® & TAI
- PG 6 –day CIDR® & TAI
3. Fixed-Timed AI (TAI) Protocols: In a fixed-time, all cows are inseminated at a pre-determined time no heat detection occurs. It is important, when considering these fixed-time AI protocols, only synchronize the number of cows that can be inseminated in a 3 to 4 hour period. Fixed-Time AI protocols include:
- 7-day CO-Synch + CIDR®
- 5-day CO-Synch + CIDR®
- PG 5 –day CO-Synch + CIDR® (For Bos Indicus cows only)
Using the Estrus Synchronization Planner can help you develop you compare synchronization protocols and develop a synchronization and breeding calendar for both cows and heifers. The planner can found on the UNL Applied Reproductive Strategies in Beef Cattle website as a free download.
Additional resources for a successful breeding season include:
- The Bovine Estrous Cycle (FS921A)
- Understanding Estrous Synchronization of Cattle (FS921C)
- Detection of Standing Estrus In Cattle (FS921B)
For more information related to estrous synchronization contact: