Manipulation of estrous cycle or induction of estrus to bring a large percentage of a group females into estrus at a short predetermined time. Estrus synchronization minimizes problems associated with estrus detection, such as labor costs and estrus detection errors. Estrus synchronization allows the more efficient use of artificial insemination with the use of elite sires having superior genetic makeup and embryo transfer procedures.

1. ASSISTED REPRODUCTIVE TECHNOLOGIES
Synchronization of estrus and Ovulation
Dr. Farooz Ahmad Lone
Assistant Professor (Ph.D Gold Medalist)

2. Assisted reproductive technologies (ART) can be defined
as techniques that manipulate reproductive-related events and/or
structures to achieve pregnancy with the final goal of producing
healthy offspring.
• Artificial insemination (AI)
• Estrous Synchronization
• Superovulation and embryo transfer (MOET)
• In vitro handling of oocytes and production of embryos
• Embryo splitting
• Reproductive cloning (SCNT)
• Embryo and semen sexing
• Transgenesis
• Genomics for marker-assisted selection
• Gene editing (CRISPR cas technology)

3. Synchronization of estrus and Ovulation
• Manipulation of estrous cycle or induction of estrus to bring a
large percentage of a group females into estrus at a short
predetermined time.
• Estrus synchronization minimizes problems associated with estrus
detection, such as labor costs and estrus detection errors.
• Estrus synchronization allows the more efficient use of artificial
insemination with the use of elite sires having superior genetic
makeup and embryo transfer procedures.

4. Basic approach
“Control the timing the onset of estrus by
controlling the length of the estrous cycle”
How to control
• Shortening of luteal phase
• Extending the luteal phase
• Use of GnRH to cause ovulation of dominant follicle

5. Shortening of luteal phase
• To induce death of CL before actual time
of luteolysis
Prostaglandins
• Natural
• Synthetic analogues
Dose and route?
• Extending the luteal phase
To mimic the action of CL
• Natural progesterone (Sponges)
• Synthetic (MGA, FGA, MAP)….30,
40, 45 mg
giving natural progesterone

6. • 0.3g of natural P4 in DICO (Dispositivo
intravaginal Caprino ovino) and CIDR-G
• Eazibreed (CIDR)…….T-shaped device
impregnated with 1.38 gm progesterone
• TRIU-B
3 medicated rings (green colour) containing
Progesterone 186 mg each and one additional
ring (pink colour) with Progesterone IP 400
mg.

7. GnRH analogues to cause ovulation of
dominant follicle
• Buserelin acetate (10-20µg)
Preparations……..
Methods of estrous synchronization
A) Prostaglandin treatment
• Cyclic females
• During breeding season in seasonal
breeders (Sheep and goat)

8. a) Single shot PGF protocol
• Estrus within 48-72 hours
PGF2α
Detect heat and breed
Day 0 Day 7 Day 21
b) Two shot PGF protocol
PGF2α PGF2α or PGF2α
Detect heat & breed
5-7 days
Day 0 Day 11 Day 14 Day 21
• Most common, breed those detected in heat post 1st PGF.
• Not in heat are injected 2nd PGF at 11-14 days apart
• In sheep 9 days apart.
.

9. B) Progesterone treatment
a) Melengesterol feeding (MGA)
Option-1: The MGA system
• Feed animals MGA @ 0.5 mg/head/day for 14 days
• After removal of MGA, most animals will show heat
• Skip this heat and breed on next natural heat
Option-2a: The MGA-PGF system
Stop MGA PGF2α
0.5 mg MGA/head/day
do not breed detect heat & breed
Day 0 Day 14 Day 31-33
Option-2b:
Stop MGA & inject PGF2α 2nd PGF2α
0.5 mg MGA/head/day 15 days later
detect heat & breed
Day 0 Day 14 Day 29
.

10. b) Synchro Mate-B (CEVA laboratories)
(3mg Norgestomet-2 ml + 5 mg estradiol valerate) (removal of implant)
6 mg norgestomet
ear implant detect heat & breed
Day 0 Day 9
Crestar: 3 mg norgestomet ear implant as against 6 mg (MSD)
• Norgestomet inhibits LH secretion which inhibits the function of the
corpus luteum.
• The estradiol valerate stimulates PGF 2 alpha release which causes a
breakdown of the corpus luteum.
.

11. C) CIDR (Eazi breed® Pfizer) 1.9 g progesterone
Removal
CIDR
detect heat & breed
Day 0 Day 7
• It maintains high concentration of P4 in blood
D) CIDR+PGF system
PGF2α Removal of CIDR
CIDR
detect heat & breed
Day 0 Day 6 7
.

12. C) GnRH based synchronization system
• Includes GnRH and PGF
• Synchronization and fertility is good
• Applicable in post partum anoestrus females
• GnRH causes ovulation of dominant follicle and initiates new
follicular wave just 2.5 days after treatment.
a) GnRH-PGF system (Select Synch)
GnRH PGF2α
Day 0 5 7 10 Day 12
detect heat and breed
• GnRH and Timed AI of non-responders on day 10 or 72 hours after
PGF…………….Hybrid Synch
.

13. b) GnRH-PGF-GnRH system
• This system includes 2nd GnRH injection between 48-72
hours after PGF injection with timed AI.
i) Ovsynch protocol (FTAI)
AI at 8-18 hours post 2nd GnRH
GnRH PGF2α GnRH
Day 0 Day 7 9 10
• Tighter synchronization
• Most females respond to this system
• Estrus in non-cycling females at 30 days postpartum
.

14. ii) Cosynch
• Similar to Ovsynch except AI is done simultaneously with
2nd GnRH injection.
GnRH PGF2α GnRH + AI
Day 0 Day 7 9
• Ovsynch requires 4 trips through the working crate but Co-synch
requires only 3.
• Ovsynch synchronizes ovulation with AI while as Co-synch does
not.
.

15. iii) Presynch-Ovsynch
• Presynchronization with PGF is used to ensure that all cows
are at the most appropriate stage of the estrous cycle at the
time of the first GnRH treatment.
• Pregnancy rate following TAI is higher in cows treated with
the “Presynch-Ovsynch” than in those treated with Ovsynch
alone (49% versus 37%).
PGF2α PGF2α GnRH PGF2α GnRH AI
12 days later 7 days later 48 hrs 8-18 hrs
Day 0 Day 14 26 33 35 36
Presynchronization Ovsynch
.

16. iv) Double-Ovsynch
• Double Ovsynch results in a higher pregnancy rate than the
Presynch-Ovsynch protocol in primiparous (65% versus
45%) but not multiparous [38% versus 40%] cows.
GnRH PGF2α GnRH 1st GnRH PGF2α 2nd GnRH
3 days later 7 days later
Day 0 Day 7 10 17 24 27 28
AI at 8-18 hours post 2nd GnRH
• The improved pregnancy rate was probably due to the increased
probability of a dominant follicle that would ovulate following
the third GnRH, and the elevated circulating progesterone
concentrations prior to the administration of PGF.
.

17. D) Progesterone-GnRH-PGF system
a) MGA-GnRH-PG protocol
withdraw MGA GnRH PGF2α
MGA
10 days later 7 days later detect heat & breed
Day 0 Day 14 24 31
b) CIDR + GnRH
GnRH PGF2α GnRH
CIDR Either Cosynch or Ovsynch
Day 0 Day 7 9
• Most common
• CIDR prevents early heat that is inherent to GnRH based system
.