The Cow-Calf Manager

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CIDRs Offer New Estrus Synchronization Option
Estrus synchronization decreases the labor associated with artificial insemination (AI), and makes timed AI feasible. Producers with smaller herds have often shied away from AI because of the time and effort necessary to breed a few cows. Several new systems have made timed AI possible, which means an AI technician could come on a single day to breed all cows or heifers. These systems included Ov-Synch and CO-synch that we have discussed before, but limited estrus detection was needed for maximum pregnancy rates. The newest systems, CIDR® based systems, show good pregnancy rates with pure timed AI (no heat checking).

Controlled internal drug-releasing device (CIDR®) provides progesterone to keep cows and heifers out of heat and synchronize estrus. The CIDR® is inserted into the vagina of the cow and releases progesterone in a controlled manner. When combined with a prostaglandin product (Lutalyse, Estrumate, In-Synch, Prostamate), a CIDR synchronizes estrus in cycling animals and induces estrus in many non-cycling females.

CIDR systems (See diagrams)
The basic program involves insertion of the CIDR for 7 days with an injection of prostaglandin on day 6 after insertion (CIDR-PGF). Cows or heifers are observed for estrus (heat) and inseminated 12 hours after observed heat. Research from a large multi-state trial demonstrated that this program was very effective in cycling cows and heifers producing pregnancy rate to a single AI of 46 % and 49 %, respectively. Over 70 % of the animals receiving the CIDR-PGF system were in heat during the first 3 days. Almost 50% of all non-cycling animals were in heat in the first 3 days after CIDR removal. Although, fewer non-cycling animals became pregnant over 25% of non-cycling animals became pregnant to AI.

Many commercial producers have opted for a modification of the CIDR-PGF by giving prostaglandin on day 7 when CIDRs are removed. The synchrony of estrus is not as tight, so most of the cows come in heat over 3 days as compared with 2 days for the standard CIDR-PGF system. The trade off is a slight reduction in synchrony for fewer trips down the chute.

Recently, research from several states indicates that adding a CIDR to GnRH-based synchronization systems (Select-Synch, CO-Synch or Ov-Synch) increases pregnancy rates in lactating beef cows. The GnRH products include Cystorelin, Fertagyl and Factrel. The addition of CIDRs to the GnRH-based systems increases the percentage of anestrus (non-cycling) cows that are "jump started" and conceive to AI by 10-15%. Adding the GnRH systems to the CIDR controls follicular development and increases fertility. Overall pregnancy rates (including non-cycling cows) to artificial insemination for CO-Synch + CIDR or Ov-Synch + CIDR average 50 to 60 %.

Some veterinarians prefer to use estradiol ciponate (ECP) in place of the first GnRH in CIDR-Ov-Synch systems for heifers. Heifers receive 1 mg ECP when the CIDR is inserted, then PGF on day 7 at CIDR removal followed by GnRH on the afternoon of day 9. Heifers are inseminated on the morning of day 10.

Cost of CIDRs
The CIDR is an over-the-counter estrus synchronization product, but the manufacturer, Pharmacia Animal Health, has limited the sources or dealership of this product. CIDRs can be purchased from breeding services such as Select-Sires, ABS and others or from veterinarians. The cost is $8.00 to $ 9.00 per CIDR. They are labeled as a single use item.

All other products listed in this article must be purchased from a licensed veterinarian with whom producers have a valid client-veterinary relationship.

Like all synchronization systems, CIDRs are no replacement for good management. Cows in low body condition or health status will respond poorly to estrus synchronization. CIDRs add another important tool to the reproductive management choices for beef producers. If you have questions about CIDRs contact your Extension Animal Science agent, breeding service representative, veterinarian or me.