Methods of Estrus Syncrhronization For Facilitating
Swine Artificial Insemination

TABLE 1
summarizes the current methods available for effectively synchronizing swine.

I. The following abbreviations are used:

• Al - artificial insemination
• PMS - pregnant mare serum gonadotrophin
• HCG - human chorionic gonadotrophin
• PG600 - 400 IU PMS 200 IU HCG
• SC - subcutaneous injection
• IM - intramuscular injection
• IU - international unit

II. Weaned Sows

A) PG600 SC or IM within 12 hours post weaning HCG 500-1000 IU IM 72-84 hours post PG600 Al twice - 24 and 36 hours post HCG OR Al once - liquid 28-32 hours post HCG frozen 30-34 hours post HCG

B) PG600 single injection within 12 hours post weaning. Al 24 and 36 hours post first standing estrus.

C) PG600 is also helpful in preventing breeding slump during hot months and with first litter gilts nursing large litters.

III. Non-cycling Gilts or Sows

A) PG600 SC or IM HCG 500-750 IU IM 72-96 hours post PG600 Al twice - 24 and 36 hours post HCG OR Al once - liquid 28-32 hours post HCG -frozen 30-34 hours post HCG

B) PG600 single injection SC or IM Al 1 2 and 24 hours post first standing estrus for gilts or 24 and 36 hours for sows.

IV. Breed Cycling Gilts or Sows at Natural Estrus

A) Abort at 1 5-40 days pregnancy 10-1 5 mg Lutalyse OR 175-250 mcg Estrumate IM 5-10 mg Lutalyse OR 75-175 mcg Estrumate IM 12 hours post first Lutalyse or Estrumate injection Al 24 and 36 hours post first standing estrus

B) PG600 SC or IM 24 hours post abortion 500-1000 IU HCG IM 72-84 hours post PG600 Al twice - 24 and 36 hours post HCG OR Al once - liquid 28-32 hours post HCG - frozen 30-34 hours post HCG

C) PG600 24 hours post abortion and Al 24 and 36 hours post first standing estrus

It should be emphasized that PG 600 does not work in cycling animals. Also, lutalyse is not very effective in synchronizing cycling swine even though it is very effective and often used in cattle. In swine there are numerous corporalutea that must be removed rather than only one as in the case of cattle. Two or three injections of lutalyse at 12 hour intervals may work in some cases but still will not be a reliable method to synchronize cycling swine.

A follicular blockage compound (progestin, trade name - Regu-mate) has been under extensive testing for cycling swine. By feeding Regu-mate for 14 to 18 days all gilts or sows will progress through the normal estrous cycle until they reach the follicle development stage. At this point the Regu-mate will prevent follicle development. Once the Regu-mate is removed from the feed, all animals should start follicle development. As a result, they will be rather closely synchronized in terms of estrus and time of breeding. However, Regu-mate has not been approved for use by the FDA in the USA and thus is not a viable alternative at the present time. It is approved and available in some foreign countries and hopefully will be approved for use in the USA.

Work conducted with lactating sows at Southern Illinois University by Harold Hodson and co-workers utilized a treatment scheme of 1 500 IU of pregnant mare serum (PMS) followed by 1000 IU of human chorionic gonadotrophin (HCG) 72 - 96 hours later. The sows were inseminated 24 hours post HCG and again at 36 to 40 hours without estrus detection. The results illustrated in Table 2 indicated that it is possible to successfully synchronize estrus and Al lactating sows on a timed basis while still in the farrowing crate.

TABLE 2
INDUCED OVULATION, ARTIFICIAL INSEMINATION AND CONCEPTION IN LACTATING SOWS

Treatment A - PMS, HCG
Treatment B - Prostagiandin F2 24 hours prior to PMS
Control - Bred by natural service following weaning

PMS has not been cleared for use in sows even though PG600, which contains PMS, has been cleared. PG600 could be used in place of the PMS. However, a double or triple dose (1 200 to 1800 IU) would probably be needed. Again, this level has not been cleared by the FDA.