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

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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

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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

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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.

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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.

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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

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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.

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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.

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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.

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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.

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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

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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.

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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.

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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.