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Dr. Bikas Puri
B.V.Sc & A.H
IAAS, Rampur,
Nepal
Estrus Synchronizatio
n
Dr. Bikas Puri
B.V.Sc & A.H
Estrus synchronization is a reproductive management tool used for manipulating the female’s estrus cycle to bring them into heat (estrus) approximately at the same time. It is used to conveniently time the artificial insemination and embryo transfer program. Hormones like progesterone, prostaglandin and their various combinations with other hormones like estrogen and gonadotropin releasing hormones (GnRH) are commonly used. However, selection of appropriate estrus synchronization protocol should be made on the basis of management capabilities and expectations of the farmer. Traditional protocols make use of hormones like prostaglandin and their analogues. Prostaglandin act by inducing the regression of corpus luteum. As prostaglandin is effective in diestrus cow it needs proper detection of ovarian status. New protocol based on the use of GnRH and prostaglandin, coordinate follicular recruitment, corpus luteum regression and time of ovulation. This OvSynch-procedure allows fixed time insemination and has proven effective in improving reproductive management in postpartum dairy cattle .
Keywords: Artificial Insemination, Embryo Transfer, Estrus Synchronization, Hormones
Estrus Synchronization in CattleAbstract
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Keep in mind that, Neither success nor failure is ever final.
Roger W Babson
Understanding of estrus cycle
Estrus is the period during which
animal stand and accept the
advances of male for mating. The
series of event that occur between
two successive estrus is called
estrus cycle. These events are:
Illustration of estrus cycle of a cow
Day 17th: Production of prostaglandin from
the uterus which causes the regression of
CL and maturation of follicle begin.Day O: Female in heat & have dominant
follicle on one of her ovaries. E2
Day 1: Rupture of dominant follicle (~28hr)
& rupture follicles start to luteinize . E2
P4
Day 5: Functional CL. P4
5
Gonadotropin releasing
hormone (GnRh), luteinizing
hormone (LH) and follicle
stimulating hormone (FSH)
allow final maturation of new
follicles on the ovaries.
Estrogen results in +ve
feedback mechanism.
Progesterone blocks this
mechanism.
Hormonal regulation during estrus
Fig: Hormonal regulation of reproduction in cattle
Source: Intervet
Estrus Synchronization involves
in manipulating the estrous
cycle within a herd to express
estrus approximately at the
same time.
A labor saving breeding
management tool effective in
artificial insemination and
embryo transfer program.
Success depend upon a
producer's understanding of how
it works.
Estrus Synchronization
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1. Shorten the AI breeding
season.
Cows or heifers are in estrus
during a predictable interval that
facilitates AI.
Reduce time and labor required to
detect estrus.
2. Result in more cows and
heifers becoming pregnant
early during the breeding
season.
Progestin-based programs can
induce estrous cyclicity in
anestrous cows and prepubertal
heifers.
Advantage
Basic approach is to control the timing of the onset
of estrus is by controlling the length of the estrous
cycle. Various approaches for controlling estrus
cycle length are:
1. Administration of prostaglandin to regress the corpus
luteum of the animal before the time of natural
luteolysis.
2. Administration of progesterone or synthetic
progestin's to temporarily suppress the ovarian
activity.
3. Using gonadotropin releasing hormone (GnRH)which
causes ovulation of a large follicle. This help in
synchronizing estrous cycle in anoestrous female.
Basic Approach of Synchronization
9
Inject all females with
prostaglandin on Day 0 and
check for estrus & breed 12
hours after standing estrus.
75% of the cycling females would
be expected to display estrus
during the next 2 to 5 days.
Anestrous cows, will not respond
to this prostaglandin protocol
because they do not have a CL
present on the ovary
Check for estrus & breed all
females in standing estrus for the
1st 5 days of the breeding season.
Inject all females with
prostaglandin not previously
bred at the end of day 5 and
breed after 12hr of standing
heat.
Cyclic cow display estrus within 2
to 5 days after the prostaglandin
injection.
Result >90% of cyclic females
being inseminated during the
first 10 days of the breeding
season.
1. Prostaglandin treatmentOne Shot Prostaglandin
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Inject prostaglandin to all cows .
75% of the cyclic females come to
heat after one injection within next 5
days and inseminate after 12hrs.
The females not detected in heat and
bred after the first injection should
receive a second prostaglandin
injection 11 or 14 days later and be
bred 12 hours after they display
standing estrus.
Two injections of prostaglandin are
given 10-12days apart.
Detection of estrus is not required
before or between injections.
All cyclic cows should respond to the
second injections regardless of what
stage of the estrous cycle they were in
when the first injection was
administered.
Second injection 14 days after the first
injection has resulted in more females
exhibiting estrus.
1. Prostaglandin treatment Two Shot Prostaglandin
11
2. Progesterone treatmentSynchronization of estrus with progestogens maintain high levels
of progesterone in the female’s system, even after the regression
of the corpus luteum.
Synchrony of estrus occurs 2-5 days following progestin removal.
Commercial product that fall into this category are
Melengesterol Acetate (MGA, oral feeding), Syncro-Mate-B (Ear
Implant) and CIDR (Intra-vaginal device).
Estrus was synchronized in only 48% of the cows treated on d3,
but the synchronization was 100%when treated on d9 of the
estrous cycle.
Longer the progestin was administered to cattle, the higher rate
of estrus synchronization, but the lower the fertility of the
synchronized animals.
12
A. MGA - Prostaglandin Protocol
MGA is fed at .5 mg/head/day for 14 days.
Exhibit estrus 2-5 days after withdrawal of the
MGA.
The estrus that occurs immediately after MGA
feeding subfertile so not to breed female.
A single injection of prostaglandin is administered
17 (or 19 days) days after the MGA has been
removed from the feeding program.
Exhibit estrus 48 - 72 hours after the PGF2a
injection.
Inseminate females 12 hours after standing estrus.
Inducing estrous cycles in some non cyclic female.
13
B. CIDR and Prostaglandin protocolCIDR contains 1.38 g progesterone.
Designed to maintain elevated blood
concentration of progesterone to at least
2ng/ml for up to 10days.
Removal CIDR decrease plasma PGF,
triggering estrus within 3-4 days.
Detect heat & inseminate from days 8 to
11.
The progestin CIDR induce estrous cycles
in anestrous cows & advance puberty in
heifers.
The majority of the females that respond
to this protocol will exhibit estrus between
25 and 72 hours after the prostaglandin
injection.
Day 0: Placing CIDR in vagina
Day 6: Inject 5ml prostaglandin
Day 7: Remove CIDR
Days 8 - 11: Detect heat &
inseminate
14
3. GnRH – Based Synchronization Systems
Recently developed protocol
GnRh causes regression or ovulation of
the dominant follicle and initiates the
emergence of a new wave of follicular
growth in avg. 2.5 d following treatment.
Control time of ovulation more exactly
and allow a single timed insemination
without the need for of estrus detection.
Four system for synchronization of estrus
with GnRH-PG combinations are
OVSYNCH, COSYNCH, SELECT SYNCH and
HYBRID SYNCH.
Day 1: GnRH used to program
follicle growth in cyclic
females and to induce
ovulation in anestrous
females.
Day 8: PGF used to induces
regression of CL that are present
to cause a decline in progesterone.
Day 10-11: GnRH induces ovulation of
dominant follicles that
pre-programmed by the
first GnRH treatment.
15
A. GnRH– PGF System “Select Synch”:
Estrus following GnRH is fertile and
cows can be inseminated.
The prostaglandin injection is not
necessary in cows that have already
exhibited estrus and not yet bred,
but will not cause any harm, either.
Do not inject prostaglandin in
females that have been bred after
the GnRH injection.
Timed insemination is not
recommended when using this
protocol.
Day 0: Inject GnRH to program follicle
growth in cyclic females and to induce
ovulation in anestrous females.
Day 7: Inject PGF used to induces
regression of CL
Day 6-13: Check for estrus and inseminalte.
16
B. Ovsynch & Cosynch Program
Day 0: Inject GnRH
Day 7: Inject PGF
Day 9: Inject GnRH (after 48 hrs.)
Day 11: Timed insemination 8 – 18 hr
after the 2nd GnRH injection.
The protocol builds on the
basic GnRH-PGF format by
adding a second GnRH
injection 48 hours after the
PGF injection.
This second GnRH injection
induces ovulation of the
dominant follicle recruited
after the first GnRH injection.
All cows are mass inseminated
without estrous detection at 8
to18 hours after the second
GnRH injection.
17
C. Addition of progesterone in the GnRH-PG :
MGA-GnRH-PG protocol:
Administered MGA orally for
14 days.
Inject GnRH 12 days after the
withdrawal of MGA.
Inject PGF2a 7d after the
GnRH injection.
80% of the cows showed
estrus within 48 to 96 hrs after
PGF2a injection.
18
CIDR to GnRH – Based protocol
1. The most common use of the CIDR
with GnRH based systems involves
insertion of the CIDR on day 1, and
withdrawal of CIDR on day 8.
2. An injection of GnRH on day of
CIDR insertion.
3. The CIDR is kept in Sutu for seven
days.
4. On the day of CIDR withdrawal, an
injection of prostaglandin is given.
5. The second GnRH injection is
given after two days of
prostaglandin injection.
6. Time breed 52- 56 hrs after PG
19
Contd……..
Advantage of CIDR to GnRH – Based protocol
1. Exposure to progesterone during the period
between day 1 and day 8, result in normal cycle in
previously anestrous cow.
2. Withdrawal of a progestin induce on set of cycles
in some anestrous females. So, the likelihood of an
ovulation is enhanced.
3. Early heat inherent to these systems are
prevented. The progesterone released by the CIDR
will prevent estrus and ovulation between days 1
and 9.
20
Success of SynchronizationFemales exhibiting regular
estrous cycles.
Good health and good nutrition
program.
A willingness by producers to
learn how to use the product
and program.
Accurate and thorough
detection of estrus.
Individual identification and
accurate record keeping system.
21
BIBLIOGRAPHYR. Islam. Synchronization of Estrus in Cattle: A Review. Vet World. 2011; 4(3):
136-141
N. E. David, P. J. timothy and C. W. Gary. 2001. Arthur’s Veterinary
Reproduction and Obstetrics. Harcourt (India) Pvt. Ltd. 8th edition.
Thatcher W.W, Moreira F, Santos J.E.P, et al: Effects of Hormonal Treatments on
Reproductive Performance and Embryo Production. Theriogenology 55:75-89,
2001.
L.E. Mc Donald.1989. Veterinary Endocrinology and Reproduction. Lea &
Febiger, Philadelphia, London. 4th edition: 545-547
http://www.jarvm.com/articles/volllssl/LOPEZ.DJVN.htm
http://digitalcommons.unl.edu/rangebeefcowsymp/150
http://beef.unl.edu
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THANK YOU……
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1. Does prolong use of hormone have got any adverse effect on the health of animal?Ans: Yes, hormone have got adverse effect on the health of animal if use in high dose for prolong period . Example: if progesterone is use for prolonged period give rise to persistent estrogen secreting follicle , premature resumption of meiosis of ova, etc.
2. Which method of estrus synchronization is best ? Ans: If the animal is cyclic at that time we can use any of the above
described protocol . However GnRH based protocol is best for non-cyclic cow.