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PREPARATION FOR LAI

by
Martin R. Dally
Super Sire, Ltd.


Essential equipment & supplies needed, if technician is traveling by air to your location:

  1. CO2 tank (10 or 20 lb tank is ideal)
  2. Laparoscopic AI cradle
  3. 2 clean pails
  4. 2 clean milk jugs (gallon size plastic recyclable ones are fine)
  5. Electric sheep shears or clippers (a 13 tooth comb will suffice)
  6. Antibiotic spray for wound
  7. Plenty of paper towels
  8. Betadine
  9. Rubbing alcohol
  10. Warm water
  11. Long-acting penicillin or other long-acting antibiotic, with syringes/needles
  12. Table for semen setup
  13. Stool for technician to sit on
  14. Electrical outlets: 2 for AI equipment, plus one for sheep shears
  15. Area with cement floor, washed if possible
  16. Shelter from wind and dust
  17. Helpers; number depends on how many ewes are being bred, and how many cradles being used. Normally at least 4 but 5 is better

Desirable but not essential items:

  1. Banamine, especially if doing LAI on older ewes. They may have stiffer tendons and ligaments and experience discomfort from restraint in cradle. Banamine provides a more comfortable recovery period
  2. A warm room for semen preparation if weather is very cold
  3. A space heater

What you will need to obtain from Super Sire, Ltd.:

  1. Either sponges or “CIDRs” (controlled internal drug release); 1 for each ewe (with perhaps a spare in case a ewe loses her sponge and it can’t be found.)
  2. PMS-G, enough to prepare 400 IU for each ewe

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 20,000 IU. The larger the vial size, the lower the cost per animal dose. The usual dose per ewe is 400 IU; contact Super Sire for exact dosages because sheep breed, season, proflicacy of flock, etc. may indicate adjustment of dose.

HORMONE SYNCHRONIZATION OF EWES

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 handle.

The sponge (or CIDR) is inserted into the ewe’s 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 the semen.

To trigger the ewe’s ovaries to prepare for ovulation:

  1. The sponge is removed
  2. PMS-G (or PG-600) is given

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 serum gonadotropin)

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:

  1. Using a syringe, withdraw 3 – 4 ml (cc) of diluent
  2. Inject this diluent into the vial containing the powder, and rock vial back & forth to mix
  3. Withdraw all of this mixture back into syringe
  4. Inject the mixture into the remaining diluent
  5. Withdraw 3 – 4 of this hormone-diluent mixture and inject it back into vial that contained powder to rinse any remaining hormone out
  6. Pull all of this out of the powder vial and inject it back into diluent vial
  7. Withdraw all of the mixed hormone solution to syringe

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 pre-measured diluent:

Use sterile saline solution or sterile water as diluent. Mix as follows:

  • For 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.
     

  • For 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 and water
beforehand.

POST-LAI CARE OF EWES

Immediately following 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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