Controlled internal drug release
Controlled internal drug release (CIDR) devices are used in livestock for the synchronization of estrus. They are T-shaped devices with a silicone-coated nylon core.[1] The silicone coating is impregnated with progesterone.[2] CIDRs are inserted intra-vaginally using a specialized applicator. The flexible wings collapse for facilitated insertion and expand once placed appropriately within the vagina.[2] The expansion of the wings retains its position; CIDRs have very high retention rates that may exceed 97%.[3] A thin nylon tail remains exteriorized and is used for removal.[2]
Once inserted, CIDRs provide slow-release administration of progesterone, which artificially extends the luteal phase.[1] Plasma progesterone levels rapidly increase upon insertion, and remain relatively consistent while in place.[4] Following CIDR removal, progesterone levels decrease rapidly.[3] Occasionally, vaginal irritation may occur. This is normal and does not impact the effectiveness of the device or the animal’s performance.[3]
There are several types of CIDRs available, including CIDR-B for cattle, CIDR-S for sheep and CIDR-G for goats. CIDRs are similar to the progesterone-releasing intravaginal device (PRID), also used for synchronization of estrous cycles in livestock.
Uses
[edit | edit source]CIDRs are approved for use in both beef cattle and dairy heifers in Canada and the United States.[2] CIDRs contain 1.9g of progesterone in Canada and 1.38g in the United States.[2] The CIDR-S is licensed for use in sheep and goats in New Zealand and Australia.[1] The CIDR-G is also suitable for use in ewes, lambs and goats.[4]
Oestrus synchronization
[edit | edit source]Cattle
[edit | edit source]In cattle, CIDR-Bs are often used with synchronization protocols. The product label typically indicates that, in conjunction with an appropriate synchronization protocol, CIDRs should be left in for 7 days.[2] Ovsynch is a particular protocol that is often followed.[5] These estrus synchronization protocols allow Fixed Time Artificial Insemination to be used, giving herd managers more accurate control.[6] The use of CIDRs with synchronization protocols helps improve reproductive performance by reducing the inefficiency associated with estrus detection.[6]
Although there is variability in the response to estrus synchronization, studies show consistently high pregnancy rates following Fixed Time Artificial Insemination with CIDR synchronization of ovarian follicle development.[2]
Sheep and goats
[edit | edit source]Previously, intravaginal progestogen sponges were a common method of estrus manipulation in ewes.[7] The development and success of CIDRs has increased their use in sheep and goats. Unlike intravaginal progestogen sponges, CIDRs do not absorb or impede drainage of natural vaginal secretions, offering a cleaner method of delivery.[1][4] They also allow administration of a natural form of hormone, as opposed to the potent analogues used in sponges.[4] A dose of 550 mg of progesterone has been found to be effective in controlling estrus and ovulation in sheep.[7]
Treatment of follicular cysts
[edit | edit source]CIDRs may be used as a treatment in cows with follicular cysts. Follicular cysts in cattle affect a significant proportion of dairy cows in several countries, and hinder the dairy industry by extending the period from calving to conception.[8] CIDRs help by reducing the Luteinizing Hormone pulse frequency and inducing atresia of cystic follicles.[8] This may also allow affected cows to be re-used in breeding or embryo transfer programs.
History
[edit | edit source]CIDRs were developed by AHI Plastic Moulding Company in Hamilton, New Zealand, in conjunction with the Ministry of Agriculture and Forestry (New Zealand).[4] Developmental trials began in 1981. The CIDR-S was licensed in 1986 and the CIDR-G in 1988.
References
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- ^ a b c d e f g Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c Eric Grant. 2006. Understanding CIDR. National Association of Animal Breeders. Feb 1, 2006. Retrieved March 20, 2012, from Beef Magazine: http://beefmagazine.com/mag/beef_understanding_cidr
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