CALLING "CARD"
DR. CLAIRE
CARD ON ‘99 AI
This article was originally printed in the June / July 2000 issue of Tracking The Industry. . .
- This article is written in grateful
acknowledgment of the contributions by Dr. Murray Woodbury, Specialized
Livestock Chair, Ron and Cathy Friesen and the clients of the Western College
of Veterinary Medicine.
The White Tailed Deer (WTD) industry is an
emerging industry in Saskatchewan. As with many livestock industries there is a
move towards increasing profitability and quality. The main products of the WTD
industry are breeding animals and monster bucks. Breeding management strategies
to make rapid improvements in genetic traits usually involve artificial
insemination. The added advantages of this industry includes the ability to
limit the introduction of disease by AI, as compared to the introduction of new
animals.
A summary of the information presented to the White-tailed
Deer Producers regarding synchronization of estrus (female receptivity) is
as follows: There are no magic formulas. Methods that may be applied usually
rely on programmed synchronization of receptivity. Methods that have been used
include intravaginal devices (CIDR's) (from Australia and New Zealand), vaginal
sponges, ear implants, and prostaglandin injections. The starting date of
treatment is usually prior to the breeding season, late October or early
November, or it may be close to the natural breeding season which appears to
coincide with the full moon in November. The hormonal devices are usually left
in place for 8-14 days and then removed. Does are inseminated 36-72 hours
following the withdrawal of the hormonal
treatment.
Progestagen-containing vaginal sponges (Veramix,
Upjohn) are available in Canada. A 10 and 12 day exposure period has been used.
Sponges tend to fall out as the doe may get hold of the strings, which need to
be cut very short, or the secretion in reaction to the sponges may soak them
and they slide out when the doe urinates. Sponge fallout usually occurs near
the end of the insertion period. The sponges are sprayed with an antibiotic
spray or coated with Alban cream prior to insertion. They can be hard to
remove. The insertion equipment for sheep may be too big for application in
small or virgin does. At removal I suggest administration of prostaglandin for
application in small or virgin does. At removal I suggest administration of
prostaglandin (lutalyse, Upjohn, 10mg (2cc) IM). This will help synchronize
does that the sponges fell out of and also may tighten the window of
receptivity. In our experience 10/24 fell out (41%) over a two year period.
Pregnancy data for 1998 was 58% (7/12), 2 does were lost to follow-up. Data on
10 more will be available in the spring. Of the does where the sponges fell
out, many were bred and became pregnant. The external signs such as a swollen
vulva, tarsal hair erection (inside of back legs at the hock), and internal
signs of receptivity such as mucus production and a soft open cervix should be
checked when deciding which does to breed. I suggest you synchronize more than
you need. Breed at about 60 hours post withdrawal of sponge. The use of 2
insertions of sponges at 5 day intervals may increase the synchronization.
Inadvertent placement of the sponge or CIDR into the urinary tract will make
the doe strain and posture as if to urinate. Remove sponge or CIDR if these
signs occur and treat with long acting goxytetracycline.
CIDR's -
These t-shaped intravaginal devices are not presently available in Canada. A 10
day treatment period is most common. These devices deliver progesterone, a
natural non-synthetic hormone, so residues from their use should not be a
problem. Few if any CIDR's fall out. We used prostaglandin as above on the day
of CIDR withdrawal. Breed at about 48-60 hours post withdrawal. Pregnancy
results are variable. Data from this year, using a non-return rate to breeding
to indicate pregnancy were 58% (14/24) in one group and 91% (10/11) in the
second group. The combined group rate was 68.5% (24/35). The 58% group was also
a group with a high proportion of does with a 1998 birth date. It is possible
to have small injuries that bleed during insertion of the intravaginal devices.
Many of the CIDR does developed a heavy vaginal discharge. Insemination was
performed by avoiding the discharge.
Ear Implants are small hard
brittle implants that were available in the US cattle (Synchromate B) but are
not presently being manufactured, and may be coming to Canada through a
European company (Crestar, Intervet) in a few years. Others report loss of
implants, but we have not had any losses. We removed the plastic coating on the
implants and then loaded one-half an implant into an implant gun from an equine
product call Ovuplant. Implants are placed under the skin of the ear. We have
non-return rate information on synchronized implanted does bred by a buck,
compared with implanted and bred AI at 60 hours post withdrawal. Prostaglandin
was given at withdrawal as above. Non-return rates were the same 93% (14/15)
for synchronized does bed with a buck, and 93% (14/15) bred AI. Another implant
and prostaglandin group bred Ai had a 71% (10/14) non-return rate. The combined
AI group non-return rate was 24/29. Note the other half of the does in this pen
were given CIDR's and are listed above at the 91% (10/11) rate mentioned
above.
Prostaglandin (Lutalyse 10 mg, 2 cc, IM) has been used in
a few animals that failed to respond to one of the above treatments. It appears
that two shots may also be used 14 days apart with no other agents during the
breeding season. The doe must be cycling if this product is to work. If a doe
fails to respond to synchronization you may wait one week, give the
prostaglandin and recheck 3 days later, breed if in estrus (receptive) at that
time. Very high doses of prostaglandin may be used to cause abortion in does,
so don't confuse it with a dewormer or antibiotic. In summary it appears the
least desirable methods, intravaginal sponges and prostaglandin, are the most
highly available in Canada. Sponges will provide synchronization but are
probably better used in mid November and should be combined with prostaglandin.
Prostaglandin is only effective when the does are in season (mid-November).
There is no clear superiority of CIDR's versus ear plants in terms of
synchronization of female receptivity. A few more years worth of data are
required to get large enough numbers to perform these comparisons. Technically
CIDR's are somewhat more difficult to insert and carry a minor risk of urinary
tract injury. In the future we need to closely evaluate the profitability of
AI. It has proven beneficial for other livestock groups to identify a short
list of products they for animal health management. It is advisable as
producers to identify these products and lobby the companies and government
agencies for their help in getting approval for their safe and legal
use.
written by Dr. Clair Card
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