CIDR insert adds to cow herd reproductive toolbox


SALEM, Ohio – Columbiana County dairyman Todd Bennett was having trouble breeding some of his Holsteins this past summer and fall. Frustrated, he blamed it on the heat.

Then, when an artificial insemination technician suggested using a new tool, he decided to give it a try.

The new controlled internal drug release (CIDR, pronounced “seeder”) insert is making all the difference.

So far, he’s 4-for-5 in conception rates and plans to keep using the tool in problem breeders.

“I’m thoroughly convinced this really works. It’s just wonderful and I’m really very pleased,” Bennett said.

Approval. The CIDR is made of elastic rubber molded over a nylon spine and requires a special applicator, sold separately.

The insert can be used to synchronize estrus in the herd as well as to induce estrus in anestrus cows and heifers.

The tool has two components: the insert, and a prostaglandin injection.

According to dosage instructions from Pharmacia, makers of the EAZI-BREED CIDR, the T-shaped inserts are administered intravaginally, one per animal, and release the hormone progesterone during a seven-day treatment period.

To assure synchronization, an injection of Lutalyse or other prostaglandin must be given to all cattle on day six, one day before the insert is removed.

The removal results in a drop in plasma progesterone, triggering estrus within three days.

“The value of that is it gives a relatively easy-to-use tool to synchronize estrus,” said Mike Day, an Ohio State University animal scientist.

“Plus you’re not giving them a hormone they don’t already have.”

Coming to America. The tool has been used with success for years in cattle in Australia and New Zealand, according to Michael O’Connor, a dairy scientist at Penn State.

It’s just now catching on in Ohio and Pennsylvania because of FDA approval in the spring of 2002.

The insert has been approved only for use in beef cows and heifers and dairy heifers.

It is not approved for use in lactating dairy cows, but researchers are investigating that use.

The old way. A similar, older option for estrus synchronization involved using an ear implant that had to be removed after 10 days.

The CIDR is easier to insert and to remove than the ear implant and reduces working time with the cattle, Day said.

Another older estrus synchronization program used prostaglandin and the feed additive melengestrol acetate, or MGA, and is still effective, but research shows increasing success with the CIDR insert.

“With no synchronization at all, you’ve got to check for heat on a daily basis. The two-injection system could program [cows and heifers] to come into heat, but [CIDRs] will cause more to come into heat in a closer time frame,” O’Connor said.

See the difference. The insert provides a way to synchronize heifers and cows and group them for calving at a specific time.

Grouping is useful for beef producers who desire a calf crop born in a short time frame to be marketed as a uniform group.

Another advantage of using the tool is savings in labor needed for heat detection.

The device has major benefits for heifers and anestrus cows, both specialists said.

The tool can start estrus in prepubertal heifers that are old enough but haven’t shown signs of cycling. CIDRs can also induce heat in cows that have calved but haven’t come back into heat.

In Day’s hypothetical herd of 150 beef cows, 100 or 125 would calve within a one-month time frame. It’s highly likely that those cows would be cycling when the herd bull is introduced for breeding, he said.

However, those other 25 cows, defined as “high risk” by Day – those that calved latest and the 2-year-olds – are ideal candidates for CIDRs.

“It’s feasible to treat those just to try to get them to start cycling,” Day said.

“I think that’s one of the areas where CIDRs are heading [for use] in beef cattle,” he said.

Research proof. The inserts have been used in both the Ohio State and Penn State herds and have shown good response, O’Connor and Day said.

In 2002 Ohio State research, 419 beef cows were identified as either cycling “easy breeders” or non-cycling, high risk cows.

In the non-cycling animals, half were treated with CIDRs.

After treatment, as many high risk anestrus animals were pregnant as were in the easy breeders group, Day said.

The addition of the CIDR restored natural pregnancy rates in the timed artificial insemination program and increased those rates by 20 percent over the high risk cows not treated with the insert, Day said.

Research trials haven’t uncovered adverse health effects related to the tool’s use.

Money in your pocket. A limiting factor for on-farm adoption of the new technology might be the cost.

The CIDRs are available without a prescription from animal health stores or through artificial insemination companies. Inserts sell for about $8.50 each and the reusable applicators run about $12 each.

“You’re trading $8 [the cost of the CIDR] apiece for earlier calves,” Day said.

“Every day earlier that calf is born is worth 2 to 2 1/2 pounds of weaning weight,” he said.

Figuring $1 per pound market prices, calving just four days earlier would more than pay for the tool’s cost, he said.

“And if you can get that cow to breed back in her first heat instead of the second, you’re easily gaining 20 days and making an extra $30 on each calf,” he said.

On the dairy end, benefits can be seen when a cow can produce more milk and more calves in a lifetime.

Facilities. The inserts are practical for most producers to use; aside from the inserts and applicators, only a chute or crowding area is necessary. CIDRs are size neutral and can be used by any size herd.

“You’ve got to handle the cows three times – once each for insertion, the injection and removal – but most people have a restraint facility so it won’t be too big of a problem,” O’Connor said.

O’Connor also said the CIDRs are easy to put in and remove.

The devices also have applications in herds that use natural service instead of artificial insemination.

“Just don’t get them bunched up too much. A bull can only service so many cows at a time,” O’Connor said.

Being realistic. The CIDR will make some cows cycle before they would if not treated at all, according to Day, and provide an opportunity for higher risk animals to get pregnant earlier in the breeding season.

However, most data would say that the conception rate of animals “kick started” with the CIDR will be lower than in females that are already cycling, Day said.

“The realistic expectation is that you will get some cows pregnant. Conception rates will be 10-20 percent lower than in the cycling cows, however.

“The data says 50 percent, but your easy breeders may be a little higher, the high risk a little lower,” he said.

“But if you get a cow started and she doesn’t catch, she’ll be back in heat in three weeks, compared to not coming into her first heat,” until maybe weeks later, Day explained.

“Getting a cow started in heat is winning half the battle.”

Another tool. The CIDR should only be viewed as another tool for reproductive management, Day said.

“It’s not going to solve all your problems and you’re not going to have 100 percent pregnancy rates in a week.

“You will get more [cows] pregnant, but it’s not a substitute for good management,” Day said.

To help increase first-time breeding and breed-back rates, Day also recommended feeding 2-year-olds correctly and implementing a controlled breeding season.

For more information, visit on contact your animal health specialist.

(You can contact Andrea Myers at 1-800-837-3419, ext. 22, or by e-mail at


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