equine artificial reproduction: how to achieve a successful outcome dr greg rodda

Dr Greg Rodda BVMS BSc Meadows Veterinary Centre http://www.meadowsvet.com.au/

Equine Artificial Reproduction

How to achieve a successful outcome

Dr Greg Rodda BVMS BSc Meadows Veterinary Centre

Introduction In 1957 the first foal was born as a result

of frozen semen For Artificial Insemination (AI) the

likelihood of success with a fertile mare & good quality semen in Australia are Chilled semen – pregnancy rates of 55-70%

per cycle Frozen semen- pregnancy rates of 45-50%

per cycle


Mare’s Reproductive Tract


Chilled Semen Insemination Advantages over

natural service Eliminates costs of

mare transport Reduced stress for

mares Increased availability

of stallions within Aust & NZ

Reduces the risk of stds

Disadvantages over natural service Collection fees

especially if multiple times

Airfares if coming from interstate

Timing of semen arrival


Frozen Semen Insemination

Advantages Semen is stored at the AI centre

so on hand exactly when needed Ability to use stallions from anywhere in the

world Genetics available after the stallion dies Decreased stress & risk to mare


Frozen Semen Insemination Disadvantages

Not all stallions freeze well or have semen that produces a pregnancy

Semen quality under a microscope may not equate to pregnancies

Pregnancy rates less than chilled inseminations Frozen semen has a shorter lifespan than fresh or

chilled More precise timing needed for

insemination Higher vet fees


Guide to Selecting a Mare for Insemination

Good reproductive history Normal findings on pre breeding reproductive

exam via ultrasound & uterine swab for non maiden mares

Poor choice mares include Poor body condition Old mares Mares that have a tendency for uterine fluid

pooling Previous inability to get pregnant Mares with a history of early embryonic loss


Chilled Semen Transport Polystyrene boxes with ice bricks

Semen in large test tubes, syringes or plastic screw top container

Semen collected is extended & cooled to 4 or 6 degrees

Semen should remain at that temperature for approx 24 hours

Shipment will usually contain a minimum of 1 billion sperm at a concentration of 25 million sperm per ml

-this is the minimum concentration that is required to achieve a pregnancy


Frozen Semen Transport & Storage Semen is collected, extended & frozen in straws of

varying sizes – most common is the 0.5ml straw Insemination dose of 0.5ml straws can be 3,4,6 or 8

straws per dose A 5ml straw is one dose Straws are shipped in a liquid nitrogen tank or a “dry

shipper” that contains only N2 vapour Straws should be able to last for 5-7days in

a dry shipper during which time they can be transferred at the AI centre into a holding tank


Mare’s Reproductive Cycle During ovulatory season (usually mid

spring to early autumn) repeated oestrus cycles of 21-22days 3-7 days of oestrus (heat) 15-17days of dioestrus where she

has a CL producing progesterone & rejects a stallion


Winter – anoestrus small follicles not growing Transitional mares in Spring

Follicles can grow over 2cm but regress non-ovulatory Mare can be in season for 14 days or more If mares have follicles over 2cm can treat with

progesterone (Ovumate) for 10 days then PG Mares may then come into season 2-4 days later –

sudden growth surge Can use lights to stimulate follicle growth from July


Timing of Insemination Prediction of ovulation important Chilled semen – 24 hours before ovulation Frozen semen – 12 hours before & up to 6 hours

post If mares in dioestrus at initial examination a PG

can be given – causes destruction of the CL bringing mare into season Works 2/3 of time other 1/3 need another PG 7 days

later Mare rescanned 3 days after PG then as necessary to

follow follicle development


Once dominant follicle gets to 35mm an ovulatory drug is given

Mare should ovulate 36-48 hours later Latest drug used causing ovulation at

approx 39 hours


Timing with Chilled Semen Scan every 36-48 hrs to see follicle growth Give stallion owner 48 hours notice for a

collection trying to ensure semen arrives less than 24 hours prior to ovulation

Semen from interstate usually transported by airfreight

Ovulation drug given when follicle over 35mm & confirmation that semen is going to be sent


Timing with Frozen Semen Method 1 Once follicle is over 35mm give ovulation drug at

8pm Scanning commences 36 hours later 8am Next scan at midday by which time most mares

have ovulated & can be inseminated If follicle still present scanning every 3 hours

until ovulation or 9pm. If mare hasn’t ovulated by 9pm it

may be a non ovulatory follicle so wait for next cycle or short cycle her.


Timing with Frozen Semen Method 2

Insemination happens twice at 12 hours apart First insemination at 24 hours after ovulation

drug has been given this will be prior to ovulation

Second insemination 12-16 hours later This technique can result in inflammatory

response to the semen & possibility of wasting semen if mare not responsive to ovulatory drug


Insemination Technique - Chilled Mare in crush with tail bandaged Vulva & surrounding area thoroughly cleaned Chilled semen placed in a non spermicidal

syringe – max volume used 100mls Sterile catheter introduced

through the cervix Semen deposited into

uterine body


Only do 1 insemination even if supplied with 2 doses – the mare will protect the semen better than leaving in fridge

Every insemination may induce a inflammatory response

All instruments in contact with semen are warmed

Motility of semen is assessed under a microscope on a warm (37 degrees) slide

Hope to see 70-80% progressively motile sperm


Frozen Insemination Post Ovulation Using the most common .5ml straws Empty rectum – clean vulva & surrounding

area thoroughly A sterile infusette is inserted through the cervix Introduce hand via rectum to guide infusette to the

ovary where ovulation has occurred. Assistant (need a good one!) thaws the straws & inserts

them 1 by 1 using a stillette Final step is semen is evaluated under the microscope Even though semen in a deep horn insemination is

deposited on the side of ovulation semen can & will travel to the other side resulting occasionally in twins


After the Insemination A) Chilled Insemination

Scan to make sure no fluid is present & ovulation has occurred

B) Frozen Insemination Scans – for fluid Treatments including flushing, use of Oxytocin &

other medications are often used as needed If fluid pooling is an issue treatments can be given for

up to 3 days Mares can then go home

First pregnancy scan day 15 – 16 post insemination then day 29 & finally day 45


Embryo Transfer

Involves the flushing of an embryo from a mare (donor) that has been inseminated & then placing the embryo into another mare (the recipient) to carry, give birth & raise.

Easy! – not quite! Recipient mare selection & timing is

crucial!


Recipient Selection Mares need to be

In good health Easy to handle 500kgs 4-10 years (younger the better) Sound breeding condition with a good breeding

history Disease free Normal on repro exam & uterine biopsy

The more mares to choose from the better A number of clients are electing to ship embryos to

Victoria where recip herds number over 100


Synchronisation It is essential by using drugs to get all the mares

ovulating at around the same time as the donor or up to 3 days after

All mares need to be prepared by giving a 10 day course of progesterone & estradiol

Then they are all given a PG injection Mares follicles will get a surge of growth Mares are scanned every 2 days from day 5 to track

follicle development They will be given an ovulation drug to induce ovulation Donor mare is inseminated with the usual protocol &

treatments


Embryo Recovery Flushing to recover an embryo is

usually done at day 7 or 8 post ovulation Special fluid is used to flush the mare with the fluid

returning out of the mare via a filter designed to collect larger particles such as an embryo

An embryo appears as a minute speck Filtered fluid is tipped into a search dish & examined

under a microscope searching for an embryo If found the embryo is washed & then either packed for

transport to a recip herd or transferred into the chosen recip mare


Transfer to Recip Mare The recip is chosen as a mare that

Closest in ovulation timing No fluid Good distinct CL Has good cervical tone

Using a pipette the embryo is inserted into the recip mare

Or if sending interstate the embryo is packed for shipping – needs to reach its destination within 12 hours


Post transfer

Donor mare goes back to work Recip mare is treated with antibiotics,

Regumate & Bute for 7 days Recip mare is scanned for pregnancy at

12-15 days If pregnant – big celebration!


Success Rates & Costs Embryo recovery at day 7 or 8 approx 50% Positive pregnancy in recip mare approx 50% Normal artificial insemination fees

Chilled insemination approx $450 plus agistment Frozen insemination approx $650 plus agistment

Embryo Transfer fees Embryo recovery $355 per attempt Airfreight if transporting interstate approx $480 Transfer to recip approx $355 Hire of Recip mare approx $2600 payable on 45 day

preg test


Meadows Vet CentreEquine Facilities

equine artificial reproduction: how to achieve a successful outcome dr greg rodda

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