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Herd Health Matters: SG Vaccination and Deworming Protocols for Recipient Cows prior to Synch & ET

  • Select Genetix
  • Aug 25
  • 4 min read


When it comes to embryo transfer (ET), most of the attention often goes to the donor cow and the quality of the embryos. But just as critical to the program’s success is the health and preparedness of the recipient cow. A well-managed herd health program—specifically, vaccination and deworming—can significantly impact conception rates.

Timing is everything. If vaccines or dewormers are given too close to transfer day, or if cows are not properly prepared ahead of time, the result can be decreased conception and higher embryo loss. Here’s why herd health protocols matter so much and how we implement them for the best results.


A recipient cow in the head chute is being vaccinated and dewormed

🏜️Geographical Considerations


Cattlemen should recognize that their core vaccination and deworming programs may need to be adjusted based on the time of year and their geographical location. Seasonal changes can impact the prevalence of certain diseases and parasites, making it crucial for producers to adjust their health management practices accordingly. Additionally, regional differences in climate, pasture conditions, and disease outbreaks can influence the effectiveness of vaccination and deworming protocols. Therefore, cattlemen must consult with their veterinarian before making any changes to their health programs, ensuring that their livestock receive the most effective and appropriate care based on current conditions.


💻Recipient Cow Vaccination and Health History


Cattlemen need to stay alert to their herd's existing parasite levels and vaccination records, as these elements can greatly impact the choice of vaccines they use. Knowing the precise vaccination and health history enables more focused prevention, instead of administering vaccines and dewormers indiscriminately. Conducting health tests can offer crucial insights, potentially leading to better management strategies and enhancing the cattle's overall health and productivity.


🧪🔬Killed or MLV?


ALWAYS READ ALL VACCINATION AND DRUG LABELS CAREFULLY BEFORE USE.

When planning a vaccination program for recipient cows in embryo transfer, it’s important to understand the difference between killed and modified-live (MLV) vaccines and how they impact reproduction.

Modified-live vaccines generally provide stronger, longer-lasting immunity, but they can pose risks if given at the wrong time. Administering MLVs to pregnant cows that haven’t been properly vaccinated beforehand may cause abortions or interfere with fetal development.

Killed vaccines, on the other hand, are safer for use in pregnant or nursing cows, though they often require booster doses to achieve full protection. For breeding-age females, MLVs should ideally be administered well in advance of breeding or embryo transfer—typically at least 30 days prior—so cows can mount a strong immune response without risking pregnancy loss. Ultimately, the choice between killed and MLV should be based on herd health history, timing within the reproductive cycle, and veterinary guidance to balance disease protection with reproductive safety.


OVERVIEW


📌 Killed vs. Modified-Live Vaccines in Breeding Cows

  • Modified-Live (MLV):

    • Stronger, longer-lasting immunity

    • Must be given 30+ days before breeding or ET

    • Risk of abortion if used in pregnant cows not previously vaccinated with MLV

  • Killed Vaccines:

    • Usually labeled safe for pregnant and nursing cows

    • Require boosters for full protection

    • Lower risk, but shorter duration of immunity

✅ Best Practice: Work with your veterinarian to time vaccinations so cows are well-protected before synchronization and transfer, without risking pregnancy or embryo loss.


💉🩺Why Vaccination Matters Before ET

Recipient cows must be protected from common reproductive and respiratory diseases that can cause early embryonic loss, abortions, or compromised fertility. Core vaccines typically cover:

  • BVD (Bovine Viral Diarrhea)

  • IBR (Infectious Bovine Rhinotracheitis)

  • Leptospirosis

  • Clostridial diseases (Blackleg, etc.)


⏰The Timing Factor

  • Too Early? If vaccines are outdated or boosters are missed, cows may not have adequate immunity, putting the embryo at risk.

  • Too Late? Administering modified-live vaccines (MLV) or even certain killed vaccines too close to transfer can temporarily stress the immune system or trigger uterine inflammation, lowering conception rates.

Best Practice: Complete vaccination protocols at least 30–45 days before synchronization and transfer to ensure strong immunity without interfering with fertility.


🪱The Role of Deworming

Internal parasites rob cows of nutrition, decrease body condition, and impair overall reproductive performance. External parasites (like lice and flies) also create stress that can reduce fertility.

  • Poor Body Condition = Lower Conception Rates: Parasite loads drain energy that should be supporting reproduction.

  • Uterine Environment: Heavy parasite burdens can stress the cow’s immune system, making her less likely to maintain an embryo.


⏰Timing Deworming

  • Too Early? Deworming too far in advance can allow parasite burdens to build back up before transfer season.

  • Too Late? Deworming too close to ET Setup can cause temporary unwanted hormone fluctuations, which can negatively impact conception.


Best Practice: Administer dewormers at least 3 weeks before synchronization so cows are clean, nutritionally supported, and past any short-term stress response.


💉Putting It All Together: A Pre-ET Health Timeline

  • 60 Days Before Synchronization:

    • Review vaccination records, booster if needed.

    • Consider sleeving each cow to be sure she is open if there is any chance she may have been bull bred after calving.

    • Assess body condition and parasite status.

    • Dial in nutritional adjustments if needed.

  • 30–45 Days Before Synchronization:

    • Administer core vaccines (MLV or killed, depending on your herd program).

    • Deworm cattle with an effective product for your region.

  • 2–4 Weeks Before Synchronization:

    • Address external parasite control (fly tags, pour-ons, etc.).

    • Ensure all visual and electronic cow identifications are legible and correlate to your herd management software or records.

  • Day of Transfer:

    • Prepare all embryo and recipient paperwork needed before you begin.

    • Handle cows calmly to minimize stress.

    • Avoid any unnecessary treatments or handling disruptions.


🧬Dialed-in Herd Health = ET Success

Recipient Cow Vaccination and Health is the cornerstone of your reproduction program's success. A healthy recipient cow is the most reliable foundation for a successful embryo transfer program. By planning herd health protocols well in advance, you give cows the best chance at high conception and pregnancy retention.

Vaccinating or deworming too close to transfer can backfire, while skipping them altogether leaves cows vulnerable to disease and parasites. The sweet spot is preparing recipients well ahead of transfer season so they are in prime health when it’s time to carry your high-value embryos.


Interested in learning more? Beef Quality Assurance provides a multitude of resources that may help you navigate basic drug usage and herd health best practices.






*** ALWAYS CONSULT YOUR HERD HEALTH VETERINARIAN & EMBRYOLOGIST BEFORE MAKING ANY CHANGES TO YOUR PROGRAM.

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