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♦ Answers to Your Most Asked Synch Questions
♦ Answers to Your Most Asked Synch Questions

Sarah Thorson, Beef Marketing and Education Manager, GENEX

There are many components to synchronization protocols, so I'm not surprised when I receive a phone call with questions nearly every week. To help with your next synchronization project, I've compiled answers to the most frequently asked questions.

What is the best synchronization protocol for cows and heifers?
There isn't an easy answer to this questions. Yes, research suggests some protocols perform better than others, but just because research says it's the best protocol doesn't necessarily make it the best protocol for your operation. I always advise people to ask themselves three questions before choosing a synchronization protocol:

> How many times am I willing to put the female through the chute?

> How much am I willing to spend on synchronization drugs?

> What are my expectations for results?

Once you know the answers to these questions you can objectively analyze which synchronization program is the best fit for your operation. No matter what the research or experts tell you, the best protocol for your operation is one that aligns with your goals and you are 100% confident you can perform perfectly from start to finish.

What criteria should I use to ensure females are good candidates for A.I.?
The answer depends if you are synchronizing heifers or cows. Criteria for synchronizing heifers:

> Should have achieved at least 65% of mature body weight

> Minimum of 50% should have reproductive tract score of ≥ 4 at six weeks before breeding
If you don't have a veterinarian in your area that offers reproductive tract scoring, don't panic! You can achieve the same thing by visually observing your heifers for heat in the weeks and months leading up to breeding. You want to observe at least 50% are cycling six weeks prior to breeding.

Criteria for synchronizing cows:

> Body Condition Score of ≥ 5 at calving

> Cows to be synchronized should have a mean postpartum interval of ≥ 40 days at the beginning of the protocol

> Each cow should be a minimum of 21 days postpartum at the time of Eazi-Breed™ CIDR® insertion

> Low incidence of calving difficulty

Where is the best place to give synchronization injections? What needle size should I use?
Synchronization drugs should be given in the muscle (IM), with the exception of LUTALYSE® Hi-Con which can be administered IM or subcutaneously. When administering synchronization drugs, I recommend using a 1-1/2 inch, 18-gauge needle. And people don't often ask, but I always mention you should wear gloves when handling any synchronization drugs to avoid contact with skin.

Can I reuse CIDR® inserts?
CIDR® inserts are labeled as a one-time use item by the manufacturer, and I recommend following this guideline. I know CIDR® inserts are one of the most expensive parts of a synchronization protocol, retailing at $10 to $12. It is tempting to cut that cost in half by using a CIDR® for a second time. The next time you are tempted to do this, ask yourself what another A.I. calf is worth to you. My guess is that it's a lot more than $5 to $6 dollars.

Can I give vaccines/dewormer while I've got the cow in the chute and am inserting the CIDR®?
A pre-breeding vaccination program is an important part of an overall successful A.I. program. However, several studies have shown injection of naïve heifers with a modified live vaccine (MLV) around the time of breeding resulted in ovarian lesions and decreased pregnancy rates. Therefore, I recommend that all pre-breeding vaccinations be given at least 30 days prior to breeding.

While there isn't any research that suggests administering dewormer at breeding will have a negative impact on fertility, I recommend doing that at least 30 days prior to breeding as well. The less stress you put on females around breeding time, the better your success. To achieve optimal results, it's best to do as little as possible to the females during the synchronization and breeding process.

How long should I wait to move the cows after insemination?
The most critical time periods for embryonic development occur between day five, when the embryo begins its migration from the oviduct to the uterus, and day 42, when the embryo has made definitive attachment to the uterus. Research indicates shipping cows during this critical time in embryo development can cause a 10% decrease in pregnancy rates. The best time to move cattle is prior to insemination or days one to four post breeding. If you can't move them within this time period, it's best to wait until after day 45. To learn more about shipping cows during this critical time period, visit the GENEX website to read a full article by Sarah Fields and Dr. George Perry (

Despite what research might say, no single synchronization protocol fits every operation. Know your operation, follow the suggestions above and trust your gut. And if you ever have any other questions, remember I'm only a phone call away.

September 2017