Estrus Synchronization Estrous Cycle Gn RH FSH Estrogen

Estrus Synchronization

Estrous Cycle § § § Gn. RH FSH Estrogen LH PGF 2α

The cycle § Gn. RH 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

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 PGF 2α § PGF 2α destroys the CL and the cycle begins again

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.

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

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.

Using Prostaglandins § One shot method: inject PGF 2α, heat detect and breed within 7 days § Two shot method – Option 1: inject PGF 2α, heat detect and breed within 7 days, inject again on day 14, heat detect and breed within 7 days – Option 2: inject PGF 2α, then again on day 14, heat detect and breed

Gn. RH based § § Give an injection of Gn. RH on day 0 Begin detecting heat on day 6 Day 7 give injection of PGF 2α On day 10 inject anything that has not shown estrus with Gn. RH and AI

MGA § § § Feed additive to control estrus Feed at. 5 mg/hd/d for 14 days Inject with Gn. RH 12 days after last feeding of MGA § Inject with PGF 2α 7 days later § Used mainly for heifers in the feedlot

CIDR § § § Insert CIDR and inject with Gn. RH on day 0 Day 6 inject with PGF 2α Remove CIDR on day 7 and begin heat detection § Should breed 48 hrs after removal of CIDR

Synchronization in swine § § § Boar exposure Lutylase PG 600

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

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