How to synchronize heifer heats with a CIDR

Synchronizing heifers just got easier.

The U.S. Food and Drug Administration recently approved a tool that makes synchronizing heifers dramatically more effective. Commonly known as a CIDR, short for controlled internal drug releasing device, the tool is a welcome addition to the reproductive repertoire of U.S. producers. (The CIDR is only currently labeled for use with dairy heifers; however, applications for use with lactating dairy cows are pending.)

The device opens the door to a whole new method of controlling estrus events. It is a T-shaped molded silicone and flexible nylon device that contains less than 2 grams of progesterone. A polyester tail is attached to the insert for easy removal.

The insert is placed in the animal's vagina. There, it continuously releases small amounts of progesterone until it is removed on the seventh day. Animals receive a pro-staglandin injection on day six of the program. This process causes a rapid drop in progesterone, which triggers estrus and ovulation.

The CIDR insert was first developed in Australia and New Zealand and is featured in breeding programs around the world. If you have dairy heifers approaching breeding age and want a high percentage of animals showing heats within a tight breeding window, this tool - used as part of a comprehensive program - can help you accomplish your goal.

This tool is pretty simple to use. Follow these detailed step-by-step instructions that were developed with the help of reproductive experts who have used the
CIDR device.

1. Before you begin, wash your hands with soap and water and put on a pair of protective gloves. Wash the applicator in a disinfectant solution before each use. Now you're ready to load the applicator. Fit the body of the insert into the applicator with the tail along the slot. The two wings will be pushed together, protruding about an inch above the top of the applicator. The device should only be used for a single application, and cost is estimated at about $8 per insert. The applicator may be used more than once.


2. Make sure that the CIDR's tail curls down and is on the underside of the applicator. Apply lubricant to the applicator. Wipe the lips of the vulva with a paper towel, just as if performing artificial insemination. Open the lips of the vulva and slowly insert the applicator at a slightly upward angle.


3. Continue moving the device forward over the pelvic bone until it meets resistance.

4. Deposit the insert by pushing on the applicator plunger. Slowly withdraw the applicator after this step.

5. Cut off long CIDR "tails" so that only 2.5 inches protrude from the vulva. This keeps curious pen mates from prematurely removing it. Some heifers may show signs of vaginitis, or irritation to the vaginal lining, after device insertion. However, when devices are removed, the inflammation clears quickly and the animal is fine for breeding.

6. Six days after inserting the CIDR device, give participating heifers a labeled dose of a prostaglandin. For example, if the device is inserted on a Monday, this injection occurs the following Sunday.

7. On day seven, it's time to remove the insert. Give the device a firm, gentle pull to remove. Dispose of used inserts. Also, make sure you recover a device from every animal that received one. That is, if you inserted a CIDR into an animal but it is not visible on the removal date, glove up and examine her to make sure the device is accounted for. Not every case of a "missing" device can be blamed on a herd mate. After removal, watch for heat, and breed when the animal comes into estrus.

Why does it work?

Why does a CIDR work so differently than a traditional synchronization program?

The combination of progesterone and prostaglandin defuses the timing issue that plagues many synchronization programs because you don't have to intercept the estrous cycle correctly to regress the corpus luteum (CL). (It is this regression that prompts the development of the provulatory follicle, behavioral estrus and ovulation, which sets animals up for breeding.)

Prostaglandin products do not regress a developing CL that is present on the ovary during the first five days of the estrous cycle. Therefore, animals in the early stages of their cycles may not respond to programs that are dependent on prostaglandin products alone.

However, when you administer progesterone for seven days, you ensure that the CL will regress in response to the prostaglandin because all animals will have a CL that has developed at least seven days.

Typically, the devices have about a 2 percent loss rate, usually due to curious pen mates pulling them out too early. If the insertion period is shorter than prescribed, watch the animal for heat and breed her if estrus appears, suggests Darrel Kesler, University of Illinois animal science professor. Just remember that the corpus luteum in some animals may not be mature enough to respond to the injection of prostaglandin.

Illustrated education

Demonstration posters for this new tool are available to help you and your employees understand how to use this technology.

Instructions are offered in Spanish and English.

To receive a copy of the poster, contact your local Pharmacia Animal Health representative or call (800) 793-0596. Or, visit

What the research shows

Field trial results reported in the April 2001 Journal of Animal Science show that heifers tested at multiple locations responded well to the CIDR and prostaglandin program. Eighty-three percent of dairy heifers treated with the device, plus a prostaglandin injection on day six of the program, came into heat within the first three days of the breeding period. In fact, the majority, or nearly 73 percent, of animals came into heat within 48 hours of the CIDR's removal.

Comparatively, 37 percent of heifers treated with prostaglandin alone came into heat during the same period.

The data also show no difference in conception rate between the two groups. These results provide a valid argument that a CIDR program makes AI even more practical for heifers because more animals in a group come into heat within a narrow window.

Still, heifers will not respond to this - or any other program - unless they have reached puberty and have a good nutrition program that supports growth and pregnancy.



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