Dr. Jigdrel Dorji gave a lecture on estrus synchronization in animals. Estrus synchronization is achieved by using progesterone, PGF2 alpha, or a combination to bring a group of female animals into heat at the same predetermined time through the use of exogenous hormones. The lecture covered definitions, hormones used, mechanisms of action, advantages, and common protocols for cattle, buffalo, sheep and goats. Protocols typically involve administering prostaglandins with or without a progestogen implant to regress the corpus luteum and induce estrus within a few days. Synchronization allows for better reproductive management and increased productivity.

1. འབྲུག་རྒྱལ་འཛིན་གཙུག་ལག་སློབ་སྡེ།
རང་འབྱུང་འཐློན་བསྡེད་མཐློ་རིམ་སློབ་གྲྭ།
སྤུ་ན་ཁ་རློང་ཁག།
ལློད་སྦུད་ས།
Dr. JIGDREL DORJI
LECTURER
ANIMAL SCIENCE DEPARTMENT
4/24/2017ESTRUS SYNCHRONIZATION 1
05/04/2017

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3. Learning outcomes.
At the end of the lesson, each student should be able to;
 Define ES (Bovines).
 Remember ES protocols.
 Recall hormones used for ES.
 Explain the mechanism of hormones for ES.
 Advantages of Estrus Synchronization.
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4. Estrus : Heat Period
Syn : Together
Chronos : Time
Bringing a group of Animals (female) into Estrus at Predetermined
Time through use of Exogenous Hormones
Estrus Synchronization
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Achieved By;
 Progesterone, PGF2 Alpha Or A Combination Of Both.
 can only take place in females that are already cycling.

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CRITERIA FOR SUCCESSFUL CONTROLLED
BREEDING
Animal requirement
Animal must be disease free - especially of
reproductive tract.
Heifer must have reached maturity with proper weight
>200-250 kgs.
Nutrition must be adequate with the animal in positive
balance.
Adequate postpartum interval of 45-60 days should be
there.
For prostaglandins it is important that the animals must
be cycling.
The animal should have a normal non-pregnant
reproductive tract.

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Management requirements
Proper timing is essential - once the program is
initiated it must be carried through all steps in proper
sequence and at proper times.
Good semen quality is an essential requirement.
Good AI technique must be followed.

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POTENTIAL ADVANTAGES
Better control of calving interval (12-13th m)
Reduction on dependence on heat detection.
Reduction of errors in heat detection.
Increased reproduction with the same number of cows.
Maintain same production with fewer numbers of cows.
Increased number of calves per cow.
Increased economic use of AI.
Reduce labor cost.

8. Hormone Origin Functions
Estrogen Dominant Follicle Induces behavioral estrus
Progesterone Corpus Luteum Maintains pregnancy and
suppresses ovulation.
Prostaglandin Uterus Regresses the corpus
Luteum
GnRH Hypothalamus Indirectly stimulates
ovulation
Hormones involved in reproduction and commonly used in
estrus synchronization protocols.
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HOW DO ESTRUS SYNCHRONIZATION PRODUCTS WORK?
Synchronization products control the estrous cycle by
influencing structures that are present on the ovary.
 regulates a female's estrous cycle by causing "luteolysis"
or regression of the CL when it is present on the ovary.
 synthetic prostaglandin will mimic natural PG release
from the uterus and will cause CL regression.
 CL produces progesterone, PG eliminates the
"progesterone block" and allows follicles to grow and
subsequent ovulation to occur.
1. Prostaglandins (PG)

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Females with a CL on their ovary when they receive an
injection of PG will usually exhibit estrus 2 to 5 days
later.
Luteolytic agents will not cause regression of the CL
during the first 4 to 6 days of the cycle in ruminants
and horses, and during the first 12 or 13 days of the
cycle in the pig.
After the progesterone block is removed, there is an
increase in follicle growth and therefore, an increase in
estrogen production and heat and subsequent ovulation
will occur 2 to 5 days after the PG injection.

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2. Estradiol Benzoate
 Estrogen used in the Syncro-Mate B protocol, will cause
regression of a CL that is 1 to 5 days old. This is the
primary reason for using estradiol instead of a
prostaglandin.
 “Estrogen is Luteolytic in ruminants but not in horse
or pig whereas PGF2 alpha is Luteolytic in all species”
3. Progesterone, MGA and Norgestomet
"hold" the female from exhibiting heat.
During a normal estrous cycle, the CL on the ovary
produces progesterone.
will play the same role as progesterone being produced
by the CL.

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Progestin will not allow the follicle to ovulate or allow
the female to exhibit heat until the synthetic progestin
is removed.
4.Gonadotropin Releasing Hormone (GnRH)
Release of luteinizing hormone (LH) and follicle
stimulating hormone (FSH) from the anterior pituitary.
LH and FSH will grow follicles and also are a part of the
process that causes ovulation.
LH and FSH are involved in follicle maturation, these
two hormones also support estrogen production from
the follicle.
 Estrogen is associated with ovulation and bringing the
animal into standing heat.

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COMMERCIAL PREPARATIONS

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Administration
Intra Muscular Route
 Natural PGF2 alpha - 25 mg.
 Synthetic analog - 0.5 mg.
Intra Vulvo Sub Mucosal Route
 Natural PGF2 alpha - 10 mg.
 Synthetic analog - 0.2 mg.
Both routes are effective and have been found to give
good conception rate.

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Estrus Synchronization Protocols
Cattle And Buffalo.
 PGF2a and its analogs are the most effective method
for estrous cycle control in dairy cattle’
 Long-term progestogen treatment of cattle is
unsatisfactory because of reduced fertility even
though estrus is well synchronized.
The following treatment protocols are available for cycling
cattle and buffalo.

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1.Give two PGF2 alpha injections 11 or 12 days apart. After
the second injection, animals may be bred/AI at detected
estrus or inseminated at 72 and 96 h.
2.Progestogen and PGF2ά: A progestogen (CIDR, PRID) is
administered as a vaginal pessary for 7 days with PGF2ά
injected on the sixth day. Cows are inseminated at detected
estrus or about 84 h after PGF2ά.
Extension of luteal Phase

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CIDR : Controlled Intravaginal Drug Releasing
Device
CIDR applicator
1.38g of Progesterone. Constant release of P4
 T-shaped devices with silicon
impregnated with P4

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3. Progestogen and Estrogen
An estrogen (5-mg estradiol valerate) and progestogen (3 mg Norgestomet) are
injected on the first day of treatment. Then a progestogen (Norgestomet) is
implanted for 9 days beginning on Day 1. Cows are inseminated based on estrus
(AIDE) or at a fixed time (TAI; 54 hours) after implant removal.

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 GnRH (Day 0), PGF2a (Day 7) and GnRH (Day 8) again and AI at
predetermined time may be used
4. GPG protocol
 it can be used at any stage of the cycle and eliminates the use of
progestogen.

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ES in Sheep And Goat
Progestogen and PGF2 are effective for synchronizing
estrus in both species, but duration of progestogen
treatment varies because of differences in the length of
the normal estrous cycle between ewes (16 days) and does (21
days).
Progestogen pessary:
 A progestogen pessary or implant is given for 12 to 14
days in sheep, and for 18 to 21 days in goats. In both
species, eCG (400 to 800 I) is given at the time of
progestogen withdrawal.
 Ewes should be inseminated at 48 and 60 h after
progestogen withdrawal and does at about 30 and 48 h.

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བཀྲ་ཤིས་བདྡེ་ལྡེགས་ཞུ།
དི་བ་རྡེ་ཡློད་པ་ཅིན་གསུང་གནང།།