The notion of getting more cows bred earlier in the breeding season to increase the total pounds weaned across the calf crop is nothing new. But the ability to achieve that in both artificial and natural breeding situations may have taken a huge leap forward.

It happened with FDA's recent approval of CIDR® (pronounced “seed-er”). A CIDR is a tiny, silicon intra-vaginal device that looks like a Y-shaped witching rod with a plastic string fastened to the longest leg. The device contains the hormone progesterone, which is absorbed at a controlled rate into the animal's bloodstream.

Progesterone is Mother Nature's magic elixir for suppressing heat and the release of both follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Combine it with a prostaglandin like Lutalyse® to regress the corpus luteum and synchronize estrus, or add Gonadatropin Releasing Hormone (GnRH) to build a timed breeding program.

Plus, research indicates that a CIDR also will jumpstart some anestrous cows to begin cycling. Thus, producers can craft a tighter window of synchronization and also place more cows within it.

For perspective, research indicates the CIDR plus Lutalyse can significantly increase the synchronization and pregnancy rates of both anestrus and cyclic cows (Table 1). One example protocol involves inserting the CIDR on Day 0, administering Lutalyse on Day 6, removing the CIDR on Day 7, and then breeding from Day 8 forward as heat is detected.

Days Equal Pounds

If you consider a 60-day breeding season and a calf gaining 2 lbs./day, that's a 120-lb. difference between the calves born on the first day of the season and the last. By using synchronization to move the average date of calving toward the front end of the season, some of the 120-lb. difference can be captured.

And that's just pounds. Other value returns can include increased uniformity and, in AI situations, getting more calves out of specific sires.

If the true proof of a product's value comes in loyal users, you can find any number of breeders in this country and others who believe CIDRs are the niftiest thing since pencils with an eraser. They decrease labor while increasing the results of synchronization.

“It adds a significant tool to beef producers who want to utilize artificial insemination (AI). It provides them with a component piece to the larger puzzle of deriving pregnancies,” says Dwight Williams, beef divisional manager for ABS Global.

With AI or natural service, there's a cost, of course, including running cows and heifers through the chute at least twice depending on the specific protocol. But Williams says, “I don't think the cost of it will be an issue, relative to other products available today.”

That's based on his company's conversations with Pharmacia Animal Health, which will be marketing CIDRs in this country as the Eazi-Breed CIDR®. According to Pharmacia, the product will retail in the $8-$10 range.

According to Fred Lehman, DVM, Pharmacia technical services manager, the Eazi-Breed CIDR device is approved for synchronization of beef cows and heifers, advancement of first post-partum estrus in beef cows and advancement of first pubertal estrus in beef heifers. While not a scrip product, Pharmacia will distribute it through veterinarians and animal health suppliers.

Given the prevalence of the devices already in this country, imported for use in research trials (also bootlegged for general use, according to some), it's worth noting the approved FDA label calls for a single use of each device.

Enhancing Not Replacing

For all of the CIDR's potential, both Williams and Lehman caution that no breeding technology can replace the fundamentals of good management. Heifers still must weigh 65% of their mature weight to begin cycling. Cows still must be in acceptable body condition if they're expected to cycle back and re-breed.

“It's just a tool. It doesn't replace good management. Remember that reproduction is a metabolic luxury,” emphasizes Lehman.

For instance, when it comes to using the product to advance the first post-partum estrus, cows need to be at least a body condition score 5 and be at least 40 days post-partum.

As always, there is no one-product-fits-all strategy. Williams points out product and protocol selections have everything to do with the goals, needs and resources of a particular operation.

Given its success in other parts of the world where CIDRs have been legal for years, this new technology bears consideration in the estrus management toolbox.

Table 1. Synchronization and pregnancy rates - first three days of breeding
Synchronization rate (%) Pregnancy rate (%)
Anestrus Cyclic Anestrus Cyclic
Control 11 19 4 11
Lutalyse 19 49 11 34
CIDR + Lutalyse 46 72 26 46
Source: Lucy, et. al, Journal of Animal Science, 2001-79:982-995