to Genetic Improvement
the Ideal Ewe
Therapy for A.I.
Shepherd Instructions and Requirments for AIing
PREPARATION FOR LAI
Martin R. Dally
Super Sire, Ltd.
Essential equipment & supplies needed, if technician
is traveling by air to your location:
Desirable but not essential
What you will need to obtain from Super
Super Sire, Ltd prefers PMS-G over PG-600, but
either one can be used. PMS-G is available in vials
containing 600 IU (international units), 6,000 IU or
larger the vial size, the lower the cost per animal
dose. The usual dose per ewe is 400 IU; contact Super
exact dosages because sheep breed, season, proflicacy
of flock, etc. may indicate adjustment of dose.
The procedures described below are designed
to cause the ewe’s reproductive cycle to be re-set
so she will cycle (ovulate) at the time of introduction
of semen by LAI
Upon receipt of your sponges & PMS-G,
keep them away from sunlight, and refrigerate the PMS-G.
Store the sponges in a cool place (less than 85 degrees)
away from sunlight, but do not refrigerate them.
If your sponges have not been dusted,
lightly dust them with sulfa dust. This cuts down bacterial
growth in the vagina, and makes sponges more pleasant to
The sponge (or CIDR) is inserted into
vagina and remains there for between 12-16 days. About
14 days is ideal. The exact time the sponge is inserted
is not critical. The sponge should be inserted far enough
to lie just beyond the bony ridge a few centimeters inside
the vagina. The string will hang outside the vagina.
Check your ewes frequently
for loss of sponges, especially during the first 24 hours,
which is when sponge loss is most likely. Maiden ewes are
more likely to lose sponges than ewes that have lambed
because the sponge cannot be inserted as far inside the
vagina in maiden ewes.
If a sponge is lost during the
first 48 hours, re-insert it immediately. If a sponge is
lost after the first 48 hours, it may cause problems with
synchronization. Re-insert the sponge immediately and keep
record of which ewe and what time the sponge was re-inserted.
The technician will examine the reproductive tract and
will not LAI the ewe if she is not ready. This will save
To trigger the ewe’s
ovaries to prepare for ovulation:
The timing for sponge removal
and administration of the PMS-G is very critical. You will
receive specific timing instructions. Timing of PMS-G injection
is arranged so LAI will take place during a time window
between 54 and 61 hours after PMS-G is given to the ewe.
For large flocks (over 50 ewes) LAI may start at 54 hours,
and for smaller flocks LAI is scheduled at about 58 hours.
LAI is timed so all ewes are bred by 61 hours. Beyond 62
hours conception rates are lower with fewer viable fetuses.
When using CIDRs (y-shaped devices) instead
of sponges, LAI is timed to take place 50-54 hours after
CIDR removal and PMS-G injection. CIDRs contain natural
progesterone, and CIDR removal does not cause a surge of
progesterone in the ewe. Sponges contain progestogen, a
synthetic hormone very similar to progesterone. Sponge
removal causes a small surge of progestogen so LAI using
sponges is timed slightly later to allow hormones to drop
low enough to trigger ovulation.
Preparing the PMS-G (pregnant mare
For each vial of dry, powdered PMS-G
you will receive a vial of diluent, which is normal sterile
saline solution. To prepare the hormone:
For the small (600 I.U.) vials: 1
ml of mixed PMS-G = 100 IU
For the large (6,000 I.U.) vials: 1
ml of mixed PMS-G = 200 IU
If you do not have vials of
Use sterile saline solution or sterile
water as diluent. Mix as follows:
the small (600 I.U.) vials of PMS-G, add 6 ml of diluent
to the dry
PMS-G. The resulting solution will contain 100 I.U. of
PMS-G per ml. To administer 400 I.U., give 4 ml.
the large (6,000 I.U.) vials of PMS-G, add 30 ml diluent
to the dry
PMS-G. The resulting solution will contain 200 I.U. of
PMS-G per ml. To administer 400 I.U., give 2 ml.
The PMS-G must be used immediately
after mixing; do not mix it ahead of time. Prepare PMS-G
15 minutes prior to pulling sponges.
PMS-G is given by IM
(intramuscular) injection. Location of IM injection is
your preference. Super Sire prefers the neck, but hind
leg also can be used.
24 hours before AI, remove feed & water
from your ewes. In cases of extreme hot weather, remove
feed at 24 hours, but leave access to water until perhaps
22 hours before LAI is scheduled to begin. Some breeds
retain water longer than others. For example, with Dorper
ewes water should be withdrawn 26-28 hr before AI, but
leave feed until 24 hr. before AI.
If ewes are on lush pasture, remove them
from pasture 48 hours before AI and feed them hay until
24 hours before AI. Pasture feeds are high in water content,
again causing full bladders.
In no circumstances should
ewes be more than 34 hours without feed. The reason for
removing access to water is a full bladder prevents visualization
of the reproductive tract, and makes good semen placement
very difficult. Feed is removed because a full rumen may
rarely be punctured by the LAI instruments and because
ewes are more comfortable during AI if they are off feed
POST-LAI CARE OF EWES
LAI, the ewe should be taken off the cradle and released
into a holding pen or pasture with feed and water. It’s
very important that ewes are not stressed after AI, and
that they begin to eat right away.
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