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Tips for choosing an estrous synchronization protocol for beef females

by Wyoming Livestock Roundup

Calves are hitting the ground all across Wyoming as we speak, and breeding season will be here before we know it. For producers who have plans to artificially inseminate (AI), it’s a good idea to start getting organized now. With many different estrous synchronization protocols available today, it can be challenging for beef producers to determine which protocol to use in an AI program.

Some common questions are, “Which AI estrus synchronization protocol is the best?” and “Which one will give me the highest conception rates?”  The answer to these questions can vary for different operations and largely depends on management style. Each operation varies in available labor, facilities, ability cover program costs, etc. Fortunately, the large variety of options make it possible to find a specific protocol fitting almost any operation, regardless of its resources.

There may be slight differences in estrus synchronization protocols, however, when correctly conducted, all protocols approved by the Beef Reproduction Task Force are very effective synchronization methods. This is because these protocols have endured scientific trials across the country and have ample data to ensure their effectiveness. 

This short list of protocols can often be found online and in many sire catalogs. In order to determine which protocol would best fit in an operation, there  are a few important things to consider.

Evaluating the condition and herd health

It is paramount prior to investing time and money into an AI program, cattle have received adequate nutrition, are cycling naturally and physically prepared to achieve successful pregnancies. Body condition scoring (BCS) is a quality visual tool used to determine body reserves available for breeding on a one to nine scale, with one being emaciated and nine being obese. 

Cows should be around a BCS 5.5 and heifers should be about a BCS six prior to breeding. If cows are thin prior to breeding, producers can expect their post-partum intervals to be longer. Therefore, thin cows will be less likely to respond to estrus synchronization and may not be good candidates for AI.

For the best results, AI candidates should be fleshy cows that had their calves early in the previous calving season and have had at least 60 days to recover. Fleshy heifers born early in their calving season and naturally cycling prior to the breeding season are also good AI candidates. 

As a rule of thumb, heifers should be at least 60 percent of their mature body weight by breeding.

Cows versus heifers

It is also very important to consider the group of animals which will be going through the synchronization protocol and manage them accordingly. Because heifers are still developing themselves, timing of treatments may differ slightly from mature cows. Therefore, to maximize success, make sure to follow the guidelines for protocols specifically designed for cows and those specifically designed for heifers.

Heifers are typically bred earlier than mature cows for various reasons. One of the most important reasons is to allow the heifer plenty of time to recover after having her first calf and setting her up for future success and longevity in the herd. Another reason is to concentrate labor around calving out heifers. 

Minimizing calving difficulty is essential for their future productivity. Sire selection via AI is a great way to minimize calving problems in heifers. 

Time and money

Two of the biggest factors to be considered when selecting a protocol is, how much time and labor is available for heat detection and the costs associated with different protocols. Protocols requiring a lot of heat detection are lower in costs and require fewer treatments in the squeeze chute. 

Conversely, protocols which do not require heat detection, i.e., strictly fixed-time AI protocols, are typically more expensive and require more treatments in the squeeze chute. Protocols requiring use of an intravaginal progesterone insert, more commonly known as a controlled internal drug release (CIDR), will be more expensive options.

A comparison of protocols table is often listed prior to the estrus synchronization protocols section of sire catalogs. Table One specifically compares protocol costs and labor demands. 

It should be noted choosing a “heat detection” protocol will require substantial time for identification of cattle showing standing heat. Misidentification of standing heat or failure to identify when cattle are in standing heat will directly affect success in a breeding program. However, good heat detection and good timing of AI can result in excellent conception rates.

Facilities and ability to handle multiple times

Working facilities which are efficient, safe and minimize stress to the cattle are highly important when selecting the appropriate protocol. Not every operation is equipped with the facilities to work large groups of cattle through a chute three or four times in a 10-day period. 

Each time an animal is handled, they are exposed to stress which can hinder success, so a smooth and efficient flow is important. Being realistic with an operation’s abilities to handle cattle multiple times may be another deciding factor in whether to use a heat detection protocol versus a fixed time protocol.  

The many estrus synchronization options available make it possible for cattlemen to AI their cattle in almost any situation possible. Whether cost, time or labor are limiting factors, there are likely options available to fit specific needs. 

The key to developing a successful AI program operation is to determine which protocol fits the situation and comply with it in all respects.

Chance Marshall is a University of Wyoming Extension Agriculture, Horticulture and Livestock Systems Educator based in Fremont County. He can be reached at or 307-332-1018. 

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