While you've likely heard of controlled internal drug release (CIDR) inserts (pronounced See-durs), you may not be aware of their benefits in improving your results with artificial insemination (AI) and estrus synchronization (ES) programs.

FDA-approved CIDR is an intravaginal progesterone insert used in conjunction with hormones to synchronize estrus in beef females. Developed in New Zealand, CIDRs are a viable alternative for producers with one or more of the following breeding challenges:

  • inefficient heat detection,

  • non-cycling cows with poor response to breeding programs,

  • cows and heifers in the wrong stage of their estrus cycles to initiate breeding, or

  • heifers that aren't cycling, even if old enough to do so.

CIDR is a T-shaped device with flexible wings that collapse to form a rod for insertion into the vagina. A tail is attached for easy removal. The CIDR's nylon spine is covered with a progesterone-impregnated silicone skin.

“CIDR is inserted for seven days,” says Cliff Lamb, University of Minnesota animal scientist. “This causes the animal's blood progesterone concentrations to rise rapidly, with maximum concentrations reached within an hour after insertion. Progesterone concentrations are maintained at a relatively constant level during the next seven days. Upon removal, progesterone concentrations are quickly eliminated.”

Because the CIDR's retention rate can exceed 97% over the seven-day period, producers needn't worry about the device falling out.

“In some cases, vaginal irritation can occur, resulting in clear, cloudy or yellow mucus when CIDR is removed. This is normal, and doesn't impact overall effectiveness,” Lamb says.

But caution should be taken when handling them, he says. Always wear latex or nitrile gloves to prevent exposure to progesterone and introducing contaminants into the vaginas of treated females.

In addition, never use CIDR inserts more than once, Lamb says, because it may increase incidence of vaginal infections.

Fixed time AI

CIDR's greatest advantage is to facilitate fixed-time AI, where no estrus detection is necessary. The protocol is simple, yet subtly different for cows and heifers:

For all females, the CIDR is inserted at the same time as GnRH (Cystorelin, Factrel, etc.) is injected. Seven days later, the CIDR is removed and the cow receives a prostaglandinF2 injection (such as Lutalyse).

In cows, perform AI at 60-66 hours after CIDR removal, and administer a second GnRH injection. In heifers, however, the interval between CIDR removal and AI with a second GnRH injection should occur between 54-60 hours.

Overall pregnancy rates should exceed 55% of all cows synchronized, which is generally better than any heat detection protocol, Lamb adds.

The CDIR-based system is ideal for producers who can't feed MGA, an orally administered progestin (acts like progesterone) feed product.

“The length of time required to feed MGA — 31 to 33 days — can be a drawback for some producers, especially during late spring and early summer when heifers are ‘grass hungry’ and less likely to consume even amounts of MGA over the entire feeding period,” Lamb says.

The CDIR program works well with existing ES programs, such as CO-Synch and Select Synch, he adds.

“To achieve optimal pregnancy rates with CIDR-based ES protocol, females should be in good body condition — usually a 5 or better — and treatments should be initiated only when cows are at least 45 days post-calving,” Lamb says.

This article is provided by the National Association of Animal Breeders. Learn more at www.NAAB-CSS.org, or call 573/445-4406.