Estrous Synchronization (Ovulation Induction)
Material adapted from lectures by Dr. Rod Geisert (Previously from Oklahoma
State University; Currently University of Missouri-Columbia)
Selected images from old lectures on this subject:
Purpose of estrus synchronization
- Group females for parturition:
- decrease labor, decrease calving period
- reduce calving season
- More uniform weaning weights.
- Reduce or eliminate estrus detection.
- Needed for artificial insemination
Cattle
- Prostaglandins - Regression of CL
- Progestins - Prevents estrus and ovulation
- CIDR, MGA
- Combined with prostaglandins
- GnRH - Ovulation, terminate follicular wave
- Combined with prostaglandins in Ovsynch
Sheep
- Progestin
- CIDR, vaginal pessary (sponge)
- In season - works alone
- Out of season - requires eCG
- Prostaglandin
- Lutalyse, estrumate
- Only works in season
- Lights - decrease day length
- Melatonin - give orally or IM
Swine
- Prostaglandin
- Not of practical use (only effect days 12 - 17)
- Progestins - Altrenogest (Regumate)
- Regumate (oral) for 18 days
- Wean Piglets
- Puberty Induction - PG600
Equine
- Prostaglandin
- Lutalyse - similar usage as cow
- Mare CL more sensitive than cow’s
- Only effective in season
- Progestins
- Regumate
- Reduce estrus behavior in competition animals
- Only effective in season
- Light
- 16 hrs day light for 60 - 90 days.
Review Quizzes
The following material is only for your own information and will not be covered in the lecture or on exams unless previously covered in lab!
Cattle:
Prostaglandin: PGF2a
| Product |
Dose and route of administration |
Half-life in blood |
| Lutalyse |
Natural compound 25 mg dose
I.M. |
2 - 3 minutes |
| Estrumate |
Analogue 500 mg dose I.M. |
3 - 4 hours |
| Prosolvin |
Analogue 15 mg dose I.M. |
2 hours |
| Bovilene |
Analogue 1 mg dose S.Q. |
18 - 24 hours |
Principle of PGF2a Use
- Regress active corpus luteum
- Only effective on day 5 - 17 corpus luteum
- Not effect on days 0 - 4
- Days 18-20 there is no corpus luteum
- In estrus 2 - 5 days after injection
- Heifers ~ 50 hrs
- Cows ~ 72 hrs
- Single injection to random animals
- To synchronized entire herd
- Give two injections 11 days apart
- Cows responding to first injection have day 6 - 9 CL by time
of second injection
- Cows not responding to first injection will have day 6 -
17 CL by time of second injection
Reasons for Variation in Response
- Stage of the follicular
wave
- day 7 PGF gets faster response due to ovulation of follicle
from 1st follicular wave
- day 10 PGF has slower response due to ovulation of follicle
from 2nd follicular wave
- Heifers react faster than cows
- Follicular growth is faster in heifers
- Animals may be pregnant
- No CL may be present - Anestrus
- Brahman cattle respond poorly to the two injection system
of PGF
- Recommended:
- Inject and breed all responders
- Inject 2nd treatment 11 days later to all those not bred
to 1st injection and breed on estrus detection
- This approach also reduces the number of second injections
needed!
Lutalyse Treatment Review
Management Consideration:
- Have proper facilities to handle animals
- Good reproductive records
- Have enough A.I. technician help
- One technician/100 cows will cause problems
- Should be around 30-50 cows/technician
- Anestrus cows don't respond to PGF2a
- No CL!!!!!!
- Be sure cows & heifers cycling
- Use good fertility semen
Breeding with Prostaglandins:
| Breeding Options |
Conception Rate |
| Breed 80 hours after 2nd injection |
31 - 80% |
| Breed based on estrus after PGF |
67% |
| Control cows bred based on estrus |
75% |
Improving Ovulation Synchronization
- 48 hours after PGF
- Give GnRH
- Cause LH surge; achieved slight increase in conception rates
Use of Progestogens
- Principle:
- Maintain the cow under the influence of progesterone until
corpus luteum regresses, remove progesterone - animal respond
to progesterone with estrus 2-5 days later.
- This treatment does not regress the CL!!!!
- Administration:
- Injection - time consuming
- Feed - mix in the ration
- Implant - place in ear
- Pessary or Control Internal Drug Release (CIDR) - place in
vagina
- Synchromate B system:
- Inject 5 mg estradiol valerate & 3 mg norgestomet, implant
norgestomet (progestagen) 6 mg
- Injection allows for rapid increase in progestin in blood
while the implant initiates its release over several hours
- Estradiol - Luteolytic to d 3-9 corpora lutea
- Norgestomet - Inhibits early C.L. development
- Remove implant 9 days later
- Rapid decrease in progestin in blood allows animal to return
to heat in 2 to 3 days.
- Breed 48 to 60 hours later or timed insemination at54 hours
later
- best conception rate if breed 12 hours after observed in
estrus
- Treatment blocks proestrus,estrus and early CL development.
Wait 9 days for diestrus cows to regress CL
- Uses:
- Sychromate B System can be used on noncycling cows which
may induce them to come into heat.
- System is not dependent on having a CL as with the prostaglandin
system.
- However, cows need to be in good condition and close to cycling
to respond
- Melengesterol Acetate (MGA) System
- Method 1
- Feed progestogen for 9 days (0.5 mg/head/day)
- Prevents estrus in diestrus and proestrus animals
- Give PGF2a on Day 8 to regress C.L.'s
- Remove progestogen on Day 9 (stop feeding)
- Cows are in heat in 2-5 days
- Alternative method
- Feed MGA for 14 days
- Don't breed on first heat (poor fertility)
- Inject PGF2a 17 days after withdrawal of MGA and breed on
estrus detection
- EAZI-BREED CIDR
- Insert CIDR (progestin) with CIDIROL capsule (estrogen) in
vagina
- Day 6 inject with PGF
- Remove CIDR Day 7 and breed on heat detection
- Can inject with CIDIROL on Day 8 and breed by timed insemination
50 hours from CIDR removal
Initiation of Puberty in Cattle
- Objectives
- Start follicular development
- Progesterone need in order to exhibit estrus in response
to follicular estrogen
- Give progestin in either feed, an implant or vaginal insert
- Procedures
- Progestin in feed, implant or CDIR for 7 - 21 days
- Follow with eCG on last day of progestin treatment
- Some heifers will ovulate even if don't give eCG
Induction of Ovulation in Postpartum Cows
- GnRH on Day 12 - 14 postpartum
- Luteinizes some follicles to produce progesterone
- First ovulation on day 35 and associated with estrus due
to progesterone exposure
Ewe
- Progestin
- Sychromate B
- Implant progestin for 12 - 14 days
- Use 1/2 Syncromate B implant
- Ewes in heat 36 - 40 hours after implant removal !!
- If do during non-breeding season, induce follicular growth
at time of implant removal
- eCG (400 - 800 IU)
- PG600
- Product designed for induction of puberty in gilts
- contains 400 IU eCG and 200 IU HCG
- Fertility in breeding season good
- Use 1 ram / 10 ewes
- Fixed time insemination at 56 - 60 hours using laproscopic
technique
- Procedure will also work with CIDR
or vaginal pessary (vaginal sponge)
- Fixed time AI at 48 - 52 hrs. after progestin removal
- PGF
- Use in breeding season only
- 2 injections of Lutalyse (20 mg ) 9 days apart
- No effect if ewe anestrus - No CL present
- Induction of Puberty in the Ewe Lamb
- Progesterone 12 - 14 days and eCG on last day of treatment
- Can give PG 600 in place of eCG alone
- Induction of ovulation in anestrous ewe
- Seasonal
- Decrease light to simulate fall
- Give melatonin
- Postpartum
- If attempting to have 2 lamb crops, treat like induction
of puberty
Sow
- PGF
- Will not cause regression of the CL until day 12 of the cycle
- Not of practical use
- Progestins
- Common progestins (MGA) will synchronize estrus but cause
ovarian cysts
- Regumate
- Product developed for horses
- Give 20 mg/day on feed for 18 days
- Estrus is 4 - 8 days after stop giving Regumate
- Only minor incidence of cysts
- Expensive
- Wean piglets
- 3 - 6 days come into estrus
- Induction of Puberty in Gilts
- Prepubertal (noncycling)
- PG 600
- 400 IU eCG and 200 IU HCG
- Gilts can not be cycling
- Need to be > 5.5 months of age
- Gilts express heat 3 - 4 days following treatment
Mare
- PGF
- Works on CL >5 days of age and mare in diestrus
- Lutalyse
- 1 ml/500 lbs. body weight
- Mare CL more sensitive than cow's
- Side effects can be sever in mare
- Sweating
- Adominal cramps, increased motility of GI tract and/or colic
- Increased heart rate
- Muscle weakness and balance problems
- All side effects begin at 5 - 10 minutes and last until 60
minutes after injection
- Ovulation in 8 - 9 days
- Reasons for treatment
- Synchronize estrus/ovulation for artificial insemination
or embryo transfer
- Prolonged diestrus - failure of CL to regress
- May remain for 3 - 4 weeks
- CL may be deep and does not regress
- Low grade uterine infection
- Embryo may have died but CL did not regress
- May treat all mares entering a breeding farm
- Shortens time to estrus and breeding
- Progestins
- Regumate
- Oral progestin
- Give 1 ml / 100 lbs body weight
- Treatment
- Feed daily for 12 - 14 days
- On last day give PGF
- Will be in heat in 3 - 4 days but ovulation not until day
8 after treatment
- Uses
- Synchronize estrus/ovulation for breeding
- Reduce number of mares in heat on any one day to better utilize
a stallion over time.
- Suppress estrus in a performance mare
- Induction of Ovulation in Anestrus Mares
- Seasonal
- Postpartum
- Breed at foal heat
- Provide adequate nutrition and don't see lactational anestrus