SELECTIONS - Fall 2003
EAZI-BREED™ CIDR®
Now Approved for Lactating Dairy Cattle
By Mel DeJarnette, reproduction specialist
In case you haven’t heard, the EAZI-BREED CIDR recently received FDA
approval for use in lactating dairy cattle. The CIDR, as it’s commonly
called, was developed in New Zealand almost 20 years ago and has proven
itself in numerous countries around the world as being a very effective
means to synchronize a fertile estrus in cattle. Introduced to the U.S.
market by Pharmacia Animal Health (now Pfizer Animal Health), the CIDR
received FDA approval for synchronization of estrus in beef cows, beef heifers
and dairy heifers in June of 2002. In late July 2003, the CIDR approval also
was extended to lactating dairy cattle for synchronization of returns to
estrus after a previous service.
What is a CIDR?
The CIDR is a T-shaped vaginal suppository with a specially engineered coating
that has been impregnated with the naturally occurring hormone progesterone.
During the normal estrous cycle, progesterone is produced by the corpus luteum
(CL) on the ovary. Progesterone has two primary functions. In cycling cows, it
prevents them from coming into estrus, while in pregnant cows progesterone is
the primary hormone responsible for pregnancy maintenance. Any use of the CIDR
could be considered similar to placing an artificial CL in the cow.
How is it used?
Virgin Heifers (Beef or Dairy)
The labeled recommendation for synchronization of estrus at first
A.I. in the United States is to insert the CIDR on day zero, inject
all animals with LUTALYSE® on day six, and then remove the CIDR on day seven
(Figure 1). However, in most every other country in the world, the recommendation
is to use the seven-day CIDR treatment but inject with Lutalyse at CIDR removal
on day seven. The day-seven LUTALYSE injection eliminates one animal handling and,
according to Select Sires field trials, simply delays estrous response by about
12 hours with little to no impact on the synchrony of estrus or the overall estrous
response rate. Insemination options following CIDR removal include: 1) heat
detection for three or four days with animals bred by A.I. eight to 12 hours
after detected estrus, 2) fixed-time A.I. at 55 to 65 hours after CIDR removal,
or 3) a combination of the above where animals are bred to standing estrus until
72 hours after CIDR removal with mass A.I. of the remainder. For insemination options
No. 2 and No. 3, research indicates an injection of GnRH at the fixed-time A.I.
may increase pregnancy rates of the animals that have not been detected in estrus.
Application of chalk or tail paint at the time of CIDR removal will facilitate
cost-effective application of GnRH treatments by allowing producers to distinguish
responding (chalk absent; no GnRH) from non-responding heifers (chalk intact; inject
with GnRH).
The wide range in the suggested insemination time for option No. 2 (55 to 65 hours)
is because we are constantly shooting at a moving target - some heifers respond
earlier or later than others. Within the estrous-response plateau, the overall
pregnancy rates likely will be similar anywhere within this range, but the actual
heifers that get pregnant may be different. That’s because we always are "robbing
Peter to pay Paul." With early A.I., you miss a few late heifers; with late A.I.,
you miss a few early heifers; if you breed in the middle, you’ll likely miss a few
on both ends. Estrous response distributions from lots of herds suggest timed A.I.
(TAI) likely is optimized when we target the middle (approximately 60 hours). There
are two ways to do this. One is to remove the CIDR late in the afternoon
(4 p.m. to 6 p.m.) and TAI three days later in the morning. This approach likely
is best when Lutalyse is given on day seven. The other option is to remove
the CIDR as early as possible in the morning and breed two days later in
the afternoon hours. This option likely is best for the day-six Lutalyse
injection as those heifers will respond a little earlier. However, in the big
picture, either option should work well with either LUTALYSE injection
day, and we’re likely hard pressed to measure a difference.
Beef Cows
For beef cows, the CIDR is used exactly as described for heifers; however, for
fixed-time A.I., a considerable amount of research indicates a favorabe response
to an injection of GnRH given at CIDR insertion on day zero. Although the benefit
is primarily reflected in improved pregnancy rates among cows that were anestrous
prior to treatment, cyclic cows appear to benefit as well, but to a much-reduced
magnitude. Thus, including the CIDR within popular GnRH-PGF based synchronization
protocols such as Ovsynch and CO-synch appears to have worked extremely well.
Although cows usually respond favorably to a GnRH injection at the time of CIDR
insertion, the results in virgin heifers are highly variable and do not appear
to consistently offer a return on investment in terms of improved reproductive
performance. A large multi-location field trial sponsored in part by Select Sires
Inc. presently is on going to evaluate the magnitude of the improved pregnancy
rate from various combinations of CIDR, LUTALYSE and GnRH in both cows and heifers,
and heat detection and fixed-time A.I. protocols. A thorough economic analysis
of the results will help to identify the most cost-effective applications.
Dairy Cows
As mentioned previously, the FDA approval for use of the CIDR in lactating
dairy cows is for synchronization of the returns to estrus. In this application,
the CIDR is inserted 14±1 days after A.I. and is removed seven days later
(day 21±1 of the estrous cycle; Figure 2). Many of the open cows then will
have a synchronous return to estrus within the next three or four days
after CIDR removal. This allows for efficient detection of returns to
estrus and more timely repeat services. In the resynchronization application,
cows should not be injected with LUTALYSE, or any other prostaglandin, as
this would cause pregnant cows to abort.
Now all cattle producers (beef and dairy) can add the EAZI-BREED CIDR to
their reproductive-management toolbox. For more information on how to get
the most efficient use and optimum return on investment from the application
of this newly available tool, contact your local Select Sires Reproductive
Solutions™ specialist.
™EAZI-BREED is a trademark of InterAg, Hamilton, New Zealand
™Reproductive Solutions is a trademark of Select Sires Inc.
®CIDR is a registered trademark of InterAg, Hamilton, New Zealand;
LUTALYSE is a registered trademark of Pharmacia & Upjohn Comapny,
a division of Pfizer Inc.
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