Estrus Synchronization
Estrous Cycle
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GnRH
FSH
Estrogen
LH
PGF2α
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
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
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 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
GnRH based
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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
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
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
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