1. Estrus Synchronization

2. Estrous Cycle • GnRH • FSH • Estrogen • LH • PGF2α

3. The cycle • GnRH stimulates the AP to release FSH • FSH acts on the ovary to begin follicular development • Follicle grows until mature and estrogen inhibits FSH • This causes the AP to release LH • LH acts on the follicle bursting the blister and causing ovulation

4. The cycle cont. • Spot on the ovary becomes the CL • CL produces progesterone maintaining pregnancy • On day 14 if the uterus does not detect and embryo then it releases PGF2α • PGF2α destroys the CL and the cycle begins again

5. Synchronization • Estrous synchronization gives many producers the opportunity to capture the economic benefits of artificial insemination (AI). • Because AI involves a substantial investment of labor and time, most commercial farms or ranches will not utilize this technology unless this investment can be confined to a period of less than 5 to 7 days. • To make the labor requirements of AI compatible, the estrous cycle must be synchronized so that a high percentage of treated females show a fertile, closely synchronized estrus.

6. Why synchronize • Because the estrous cycle is 21 days long, you can only expect to catch about 1/3 of the cycling animals in heat during the first week of the breeding period if you don’t use estrus synchronization. • Regardless of whether the animals are inseminated naturally or artificially, you can only expect 65 to 70% of them to conceive to a given insemination. • Thus, after a week of breeding to natural heats, only 21% of the eligible animals could possibly be pregnant

7. Why synchronize • Many estrus synchronization protocols can induce 75 to 90% of the cycling animals to display estrus within a 5 day period. • Additionally, many protocols can induce a fertile heat in as much as 50% of the anestrous cows.

8. Using Prostaglandins • One shot method: inject PGF2α, heat detect and breed within 7 days • Two shot method • Option 1: inject PGF2α, heat detect and breed within 7 days, inject again on day 14, heat detect and breed within 7 days • Option 2: inject PGF2α, then again on day 14, heat detect and breed

9. GnRH based • Give an injection of GnRH on day 0 • Begin detecting heat on day 6 • Day 7 give injection of PGF2α • On day 10 inject anything that has not shown estrus with GnRH and AI

10. MGA • Feed additive to control estrus • Feed at .5mg/hd/d for 14 days • Inject with GnRH 12 days after last feeding of MGA • Inject with PGF2α 7 days later • Used mainly for heifers in the feedlot

11. CIDR • Insert CIDR and inject with GnRH on day 0 • Day 6 inject with PGF2α • Remove CIDR on day 7 and begin heat detection • Should breed 48 hrs after removal of CIDR

12. Synchronization in swine • Boar exposure • Lutylase • PG 600

13. Boar exposure • When sows or gilts are put together and exposed to a boar everyday their cycle will synchronize with each other. • Also helps bring them into heat

14. Lutylase & PG 600 • Lutylase acts the same as does in cattle • PG 600 is combination of PMSG and HCG • Given in combination with lutylase will give stronger heats and better conception • We use these two with boar exposure to synchronize our sows