Estrous Synchronization

What is the goal?

control estrus (heat) and ovulation in females so that breeding can be completed in a short period of time

What is an advantage of having synchronized breeding season?

~add a 4th cycle and reduce the length of the first

~older age by calving + larger size for market

Potential advantages of estrous synchronization

~can shorten breeding season

~shortened time for breeding

~utilizes labor more efficiently

~no heat checking needed

~reduced days to first service

~groups timing of parturition: uniform crop of offspring

Potential disadvantages

~timing is everything

~increased labor costs

~requires skilled labor and periods of intensive management: multiple injections

~requires adequate facilities: less time spent observing animals, can miss detecting non-cyclers

~higher input costs: need to examine economics first, costs balanced by increased returns (feedlot out west= sure, local feed lot= maybe not)

Manipulation of the cycle

Prostaglandin: lutalyse, estrumate, prosolvin, bovilene, ETC (target CL and regress it)

Progestins: progesterone, MGA- melengestrol acetate, Norgestomet, PRID: Progesterone Releasing Intravaginal Device, CIDR- controlled internal drug release (mimic hormone from CL)

Prostaglandin: PGF2a, regress active corpus luteum

~Regress the active corpus luteum: only effective on the day 5-17 corpus luteum, no effect on days 0-5, days 18-20, there is no corpus luteum (undergoing luteolysis)

~5 to is ideal: CL needs to become sensitive to PGF2a

Prostaglandin: PGF2a, in estrus and injections

~in estrus 2 to 5 days after injection

~heifers: ~50hrs

~cows: ~72 hrs

~60 to 65% will respond

~two injections to synchronize entire herd

Prostaglandin scenario

~2 to 14 days apart

~Monday: everybody, 60-65% estrus Thursday

~10 to 14 days later, everyone gets shot

~now everyone should have CL to respond

Factors to consider…

~Prostaglandin F2a and analogs: pharmaceuticals

~animals MUST be cycling (only targets CL, not in estrous not gonna work)

~easy to use

~cost ($1-3 per dose)

~can be combined with GnRH for timed AI

~precautions needed, vasoconstrictor

Synch with PGF2a

~Inject PGF on day 0, then heat check & AI 2 to 7 days later

~then inject PGF again on day 12 to 14, heat check & AI again 2 to 7 days later

~variations: single injection after palpation of CL or heat check 5 days, single injection

~only inject those with CL

Why do we do 2 injections of PGF?

~animals not responsive before day 7

~ensures we get all of them

Goal Progesterone

Suppress estrus by reding GnRH pulses thus preventing the pre-ov LH surge

Does using only progesterone regress the CL?

~THIS TREATMENT DOES NOT REGRESS CL, need PGF for that

Administration of progesterone in livestock and trade-offs

~injection: time-consuming

~feed- mix in the ration

~implant: place in ear: taken off market, long term, residue

~pessary or Control Internal Drug Release (CIDR)- place in vagina

Progesterone and MGA: melengestrol acetate

~Progesterone: can be used with a proper delivery method (CIDR)

~MGA: cheapest (pennies per day): top dress feed, Oral administration (ease of use, less control of therapeutic levels (boss/subordinate cows not everyone getting same dose), longer treatment time required (used longer better to respond)

Norgestomet (Syncro-Mate-B) and PRID and CIDR

~Norgestomet: no longer on market, worked too well, has to be removed, ineffective to be removed fully, residue

~PRID and CIDR: easy to use, multiple inserts can be used to alter therapeutic levels, retention rates of about 95%, and storage of used devices (throw them away, get into the environment)

CIDR recommendation

~ implant for 7 days

~inject PGF on day 6 or day 7

~heat check and breed after heat for the next 3 to 4 days after CIDR removal

~day 0 to 7: have CIDR

~remove 7: PGF, wait 72 hrs, breed on day 10

How does the CIDR stay in place?

~the Y shape, mucus membranes pick up progesterone

Contraceptives for humans

~oral: next month fertility, take them for a couple of days, then take a placebo to have menses at 28 days

~transdermal: 1st patch at day 6, then another at 12-14, then another at 20, then have a patch-free week, about a week at a time

~injection: 3 months at a time

~implant: works for 5 years, metabolism factors, return to fertility: takes longer to fertility, 6 to 8 months

OV-synch

~first one

~GnRH at day 0, ovulate follicle (85% cows), start new follicle wave (100%), resets follicular wave

~PGF at day 7, regresses CL

~GnRH after 30-48hrs, on day 8 to 9: ovulate follicles

~Time breed: same preg rates for AI with heat detection (~40%)

Select-synch and Select-synch + CIDR

~day 0, GnRH (wouldn’t respond) and ovulate somewhere between day 0 and 7

~PGF day 7 the heat check and breed until day 13, no GnRH

~To help with ovulation, add CIDR between 0 to 7, pull at day 7, and continue with the previous

Co-Synch Regular

~same as select except at the end, when we give PGF on day 7, we wait 48 hrs then give GnRH & breed at day 9, allowing for timed breeding

~GnRH at day 0, resets the ovary and starts a new follicular wave

Co-synch + CIDR (7 day)

~give GnRH at day 0, insert CIDR

~wait 7 days and remove at day 7, give PGF, this removes exogenous progesterone and ensures that luteolysis occurs

~then 60 to 66hrs after we give GnRH & breed at day 10

~ This is the most common and works well with the physiology of the animal

~works Monday to Monday, breed Thursday/Friday

Co synch + CIDR (5 day)

~Give GnRH at day 0, insert CIDR

~PGF on day 5, then again 8h later, this is to ensure they respond, 60% will respond to first shot, but we will be closer to 100% with second

~72hrs later we will give GnRH & breed on day 8

Overall hormone profile for Co-Synch

1) PGf2a= decrease P4, kill CL

2) P4, block ovulation, block LH surge

3) stimulate ovulation

Advantages of Synch methods

~shortened time to AI (10 days after trt), 8 to 10 days

~no heat checking needed

~reduced days to first service

~comparable first service conception rates

Disadvantage of Synch methods

~drug cost increase

~multiple injections required, more labor

~less time spent observing animals (can miss detecting non-cyclers in the herd)

~60 to 90-day calf, separate cow + calves, 5-day: remove twice, not a fan b/c you increase labor

Cost, chute time, estrus detection

~more expensive, $2/$5/ $12 CIDR

~invest more time in the more injections we give, but we don’t need to heat check them as often

~spontaneous, we have to observe more animals

~more complex=more labor

Comparing the options

~varies

~need to access if the 4% increase in # of calves is worth the labor?

~depends on op and market

Advantages to using Natural service with synch

~AI not required: less labor, facilities, and skills required

~no heat checking required

~good conception rates

~normal bull to female rations used/ 1 to 10 to 1 to 34 not different

~shortened breeding/calving season

Disadvantages to using natural service with synch

~males should be proven sires: match to females

~sires should be experienced

~BSE (Breeding Soundness exam) strongly recommended

~Bulls must be maintained through year: not just during breeding season: rentals not as popular due to STDS

~drug cost fro sych

~bulls '“tired” after synch period: rest to not completely decrease fertility

Main points for Cattle

1. Prostaglandins only work with cycling animals

2. Progestins and GnRH can help anestrous animals cycle. But must include prostaglandin in the program

3. For timed AI must control the follicular wave (GnRH: controlling/synch ov)

4. Need resources (personnel, time, access to estrus synch products

5. Market plan? participate in calf pool or sale by pot load?, sale at local auction? supply local beef to farmers’ market?

6. adequate facilities

Sheep and Goats overview

~methods used in cattle work for these

~ methods: buck effect, light therapy (Artificial day length)

~hormone therapy: progesterone treatments (CIDR), Prostaglandin (Lutalyse, Estrumate) injections, Chronic GnRH (PG 600) injections

Buck effect

~strategic exposure of does to intact males will result in the ewes displaying estrus approximately. 7 to 10 days

~sight, sound, smell, 60 day isolation

~rams need to be isolated from doe’s sight & smell for appox 60 days

~effective during short day lengths: helps with long but not as effective

Light therapy: artificial day length

1. suppress cyclicity: two months of 16-19-20 hour days, one to two hours of bright light 16 hours after dawn for 2 months

2. induce cyclicity: return to short day length, does start cycling in about 6 weeks

3. add buck for added effect, consider electricity bill, windows blacked out

NOT VERY COMMON

Inducing estrus in breeding season

~need progesterone supplementation for 11 to 14 days (CIDR: preferred method of progesterone supplementation)

~can use PGF2a when removing CIDR but NOT REQUIRED, do not need extra hormones (eCG or PG 600) to stimulate ovulation

~method optimum for getting ewes to cycle together for uniform lamb crop- but for timed AI

~ewes will display estrus in 1 to 3 days following CIDR removal

Inducing estrus in the breeding season part 2

~no progesterone supplementation approach

1. make sure ewes are cycling

   1. give ewes first injection of PGF2a (10 to 15 mg) on day 0, wait 7 days to 10 days

   2. give ewes second injection of PGF2a (10 to 15 mg) on days 7 to 10

   3. Ewes will display estrus in 1 to 3 days following second injection of PGF2a: fertility may be lower the progesterone supplemented programs

Inducing estrus in acylic (out of season) ewes

~need progesterone supplementation for a min on 5 days (typical is 7 or 10 days): CIDR and MGA (feed additive) NEED BOTH

~when progesterone is removed, need to stimulate OVULATION

1. eCG (-400IU), FSH & LH-ov

2. PG 600 (dose-400 IU eCG & 200 IU hCG), combination eCG and hCG

Out-of-season synchronization protocol

~CIDR + PG 600; 10 day CIDR treatment

1. 2.5cc PG 600 1 day before removing CIDRS

2. Estrus ~2 days after CIDR removal

3. Can Ram breed or breed time AI at 48h after CIDR (1cc GnRH at time of AI breeding)

~Key issue: antibodies develop to PG600? resistant to it, maybe not at low does; high does can limit use

~april, may sometimes June

Estrus synch in horses

~long day breeders: mare may not cycle in April

~light treatment begins in 60 to 90 days before the desired breeding date

~Hormonal regulation: GnRH, PGF2a used (with care): sensitive, don’t break it down well

~progestins used to prevent heat (regumate, oral)

Goats

~NCSynch: a novel, progesterone-free protocol for ovulation synchronization and timed artificial insemination in goats

~used commercially available hormones to regulate the timing of ovulation

~achieved pregnancy rates comparable to animals inseminated following estrus

Methods to advance the onset of cyclicity in horses

~lights

~need 10 foot candles or 1 lux (100 watt bulb in a 12 by 12 box stall or two 40 watt fluorescent bulbs/ box stall)

~abrupt method ( 14.5 to 16h of light)

~gradual method (increase 1h/ week)

~intermittent method (10L-8D-2L-4D), photosensitive period (inducible period): one hour of light, 9.5 to 10.5 h after the onset of darkness

Swine estrus synch

~synchronization not used frequently

~PGF2a not effective until AFTER day 12 : no advantages to synch sows, MATRIX: gilts, synch estrous to breed together

~lactating w/piglets, suppress heat, wean piglet day 21, 7 to 10 days after weaning, go back into cycle

~challenge of acquisition of luteolytic capacity

Matrix program

~matrix top dress on feed for 14 days

~85% of gilts fed were in estrus 4 to 9 days after cessation of feeding

~could be used as synchronization gilts for entry into the breeding herd

~estrus around 5 to 6 days

~give 14 days straight, remove, all estrus within 3 days