Cycle synchronization
Estrus Synchronization
Laparoscopic insemination involves the well-planned technical procedure, that mostly depends on the efficiency of synchronized oestrus, the quality of the ova and semen. Estrus synchronization is achieved by placing progesterone sponges in the sheep's vagina, where they stand for 12 - 14 days (the maximum range can be 12-17 days). When extracting a sponge, sheep are simultaneously injected with Pregnant Mare Serum Gonadotropin (PMSG).
While sponges are in the vagina, sheep should avoid high temperatures. PMSG stimulates the sheep to enter the oestrus in the period from 14 to 18 hours, and at the same time can serve to increase the number of ovulations (increasing tweening rate, triple, etc.). If you have a limited number of rams or plan to inseminate two groups of sheep consecutively, with two or three days apart, the sheep may receive sponges at the same time, but they are pulled out in two or three days. For example. sponges would remain in sheep for 12, 14 or 16 days.
A lot of mucus and a strong odor will be noticed when removing the sponge. If good hygiene is practiced while inserting a sponge, there will be no negative effect on the success of conception. The vaginal discharge will clear before entering the oestrus.
Sponges should be collected and disposed of appropriately. Leaving used sponges in sheep barn can lead to the consumption of sponges by dogs and their death.
Joining rams to sheep is performed 48 hours after sponge removal and application of the PMSG. Laparoscopic insemination is performed 55 ± 5 hours after sponge removal. Earlier breeding is not desirable because sheep are already entering in estrus but ovulation will be in 24 hours later. If the quality of the semen is good, as well as the fertilizing capacity of the ram (pronounced libido, high testicular volume), there will be no problem. Joung sheep have shorter estruses.
It is advisable to learn the habits of the ram. He may "fall in love" with one sheep (usually an older one) and neglect the others. If this is the case, the dominant sheep should be removed from the shed, as well as separating older sheep from young ones in a synchronized group).
Administration and doses of PMSG:
PMSG comes in powder form (lyophilized) and doses are expressed in international units (IU) which, after dilution, are calculated in volume units. For example, one vial of PMSG contains 1.000 IU. It is reconstituted with 5 ml of water for injection. Often, small sheep receive 500 i.j. in 2.5 ml of solvent.
PMSG is sensitive to temperature changes. It must be stored in a fridge (5 - 10° C), protected from sunlight, and must be used within 24 hours after reconstruction with water. Accuracy in the application is essential, so use small syringes and thin needles. It has to be given deep intramuscularly.
It is necessary to use the PMSG to ensure good synchronization. High doses cause multiple ovulations, which could lead to more lambs being born. The standard dose is 400 - 500 i.u. for smaller and lighter sheep (domestic sheep in the season), while for larger, heavy breeds needs 550-700 i.u. (depending on the season, weight, body condition scoring, etc.). Overdoses lead to the birth of fours, fives lambs, which can increase the death rate. Insufficient doses will not cause ovulation. It is best to estimate the dose immediately prior to administration to each individual. Also, owner affinity and its managing abilities determine the doses that is applied.
The history of the herd, the diet and the condition of the sheep always have an important influence on the insemination results. In flocks of sheep that have a history of high conception rates, a good percentage of tweening, good body condition scoring, then the PMSG dose can be reduced to 400 i.j. When opposite conditions prevail, in a herd with poor breeding history, with poor nutrition, then the dose must be increased.
Most breeders after successful AI cycle are looking to increase the number of live births by injecting higher and higher doses, depending on nutrition, breeding history, and mating season. This can be possible to some extent, but hard-working period, artificial rearing and best possible nutrition and health care should be provided properly and on time. The Centre's experts will help you determine and adjust your upbringing needs and opportunities, depending on the breeds used.
The PMSG is mainly applied at the time of removal of the sponge and is given deeply intramuscularly. The time between the removal of the sponge and the insemination is very important, as the ovulation takes place about 58-60 hours after the removal of the sponge. It is very important that insemination be carried out beforehand, especially when using fresh seed. Young sheep tend to ovulate earlier, there are even some differences between breeds and season. Using CIDR, sheep enter and ovulate 4 hours earlier than with the sponge. Sheep CIDR is not yet registered in our market.