Overview

Producers and researchers agree that the benefits of utilizing a synchronization protocol to induce estrus (heat) in a herd can often outweigh protocol costs. These benefits occur when breeding by artificial insemination (AI) and by natural service. Yet, looking through dozens of protocol options to decide on the best fit for your herd can be frustrating. So, what steps do you need to take when making this decision?

Points to Consider

Are you synchronizing mature cows or heifers?

This will determine which hormones are needed in the protocol. Communication between a heifer’s brain and her reproductive tract is still being fully established, even after she has reached puberty. Therefore, the protocols used on mature cows may not be a good fit for your heifers.

What are your goals with synchronization?

If you can use AI as they come into heat, there are a variety of protocols that could fit your operation. When you are breeding by AI on a single day, you need a slightly more intensive fixed-timed AI (FTAI) protocol. In contrast, if natural service is being used, a one-shot protocol could be ideal.

What does your labor force look like?

Some protocols are more labor-intensive than others. Knowing how many times you can, or are willing to, run animals through the chute can narrow your protocol options.

Does your budget have room for the up-front costs?

It can be difficult to understand how much profit will be gained until calves are sold for the first time. This is where you can benefit from having many protocols to choose from.

Figure 1. Heifers that have CIDRs inserted during an estrus synchronization protocol. Photo by Ashley K. Edwards

Figure 2. Cows waiting to be bred by artificial insemination. Photo by Ashley K. Edwards

Hormones and Synchronization

Let us circle back to the first question for a moment and discuss the hormones used in synchronization protocols. Progesterone and prostaglandin may sound similar, but they function in opposition to each other. Oftentimes, protocol diagrams use abbreviations and use a mixture of brand-name products with hormones. Below are the major hormones used in synchronization protocols, their functions and a few products for each:

• Gonadotropin-releasing hormone (GnRH) functions to stimulate the release of both luteinizing hormone (LH) and follicle-stimulating hormone (FSH). For synchronization protocols, it is administered to induce ovulation.
  • Common products include Cystorelin, Fertagyl and Factrel.
• Progesterone (P4) has several functions in the body, but for synchronization protocols it is administered to suppress production of other reproductive hormones (GnRH, LH, FSH and estrogen). This allows females to essentially restart their estrous cycle for synchronization.
  • Common products include EAZI-BREED CIDR and Melengestrol acetate (MGA).
• Prostaglandin (PG or PGF2α) functions to lyse or destroy the corpus luteum. This will halt production of progesterone, allow follicles to develop again, and females to come into heat and ovulate. Heat will occur approximately 48 hours after administration. Importantly, prostaglandin can cause abortion in pregnant females.
  • Common products include Estrumate, Lutalyse and Lutalyse HighCon.

Thankfully, sources such as the Beef Reproduction Task Force have worked to group protocols separately for cows and heifers. There is a list of available products for each hormone needed, along with cost and labor comparisons between protocols. Their information can be found under the Resources section of their website at https://beefrepro.org/resources.

Summary: Implementing a Plan

Most synchronization products require a veterinarian’s prescription and can take weeks to arrive. The decision to implement estrus synchronization should not be made at the last minute. Work with your veterinarian or reproductive specialist to establish the best protocol for your operation and order supplies ahead of time. Proper planning and the proper protocol can lead to increased profits.

For more information or questions, email Ashley Edwards at akedwards@agcenter.lsu.edu.