Estrous Synchronization (Ovulation Induction) and Ovsynch

1. Estrous Synchronization (Ovulation Induction)and Ovsynch John Parrish

2. Learning Objective To understand how estrus synchronization and Ovsynch work along with how to use it successfully.

3. Estrus synchronization: Why? 1. Group females for parturition: a. Labor, Calving period b. More uniform weaning weights. 2. Reduce time required for estrus detection. 3. Eliminate estrus detection with timed insemination: Reduce calving season Fertility may be higher in combination with estrus detection.

4. Cattle: Half-life in blood • Prostaglandins: PGF2a • Lutalyse - Natural compound 25 mg dose I.M. • Estrumate - Analogue 500 mg dose I.M. • Bovilene - Analogue 1 mg dose s.q. 2-3 min 3-4 hrs 18-24 hrs

5. Principle of PGF2a Use • Regress active corpus luteum • Only effective on day 5 - 17 corpus luteum • Not effective on days: • 1 - 4(CL not responsive) • 18 - 21(CL already regressed)

7. Lutalyse Inject Lutalyse to those with a CL 11 days 1 injection + palpation Palpation to detect CL Inject Lutalyse to those not getting the 1st injection Heat Check & Breed

8. Principle of PGF2a Use • In estrus 2 - 5 days after injection • Heifers ~ 50 hrs • Cows ~ 72 hrs

9. Follicular Size 7 Ovulation 10 Day After Ovulation Reasons for Variation in Response • Stage of the follicular wave at time of PGF2a

10. PGF2 PGF2 Reasons for Variation in Response • Stage of the follicular wave Follicular Size 7 Ovulation 10 Day After Ovulation

11. PGF2 PGF2 Reasons for Variation in Response • Stage of the follicular wave Time to response depends on stage of follicular wave! Follicular Size 7 Ovulation 10 Day After Ovulation

12. Reasons for Variation in Response (cont.) • 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 PGF2a • 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!

13. 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

14. Breeding with Prostaglandins: 1. Breed 80 hours after 2nd injection 2. Breed based on estrus after PGF2a 3. Control cows bred based on estrus Conception Rate 31 - 80% 67% 75%

15. Improving Ovulation Synchronization • 48 hours after PGF2a • Give GnRH • Cause LH surge; achieved slight increase in conception rates • 3 - 4 % Cystorelin (GnRH Analogue)

16. 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. Administration: Injection Feed Implant Pessary or Control Internal Drug Release (CIDR) This does not regress the CL!!!! Time Consuming Mix in ration Place in ear Place in Vagina

19. Lutyalytic to day 1-4 CL Triggers GnRH surge Estrogen EAZI-BREED CIDR Beef Cow Day 9-11 Day 6 Day 7 Day 8 7 Days Insert CIDR with CIDIROL capsule Inject PG Remove CIDR Inject 2mL CIDIROL Detect Estrus or Inseminate Fixed-time 50 hours From CIDIROL

20. Initiation of Puberty in Cattle • Objectives • Start follicular development • FSH or eCG • Progesterone need in order to exhibit estrus in response to follicular estrogen • Give progestin in either feed or vaginal insert • Procedures • Progestin in feed 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

21. 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 • Ovsynch

22. Timed AI 8 - 18 hours Ovsynch GnRH PGF2 GnRH 7 Days 36 - 48 hours

23. How Does Ovsynch Work? • Ovsynch does not change conception rate • Ovsynch dramatically improves service rate

24. Treatment: Description: Estrus detection with a.m./p.m. AI Synchronization of ovulation with timed AI Experimental DesignField trial using lactating dairy cows from three herds in South-central Wisconsin Control (n=166) Ovsynch (n=167)

25. Methodology • Voluntary waiting period = 50 days • Pregnancy diagnosis was determined by ultrasound 32 to 38 days post-AI • Nonpregnant cows remained in the same treatment group until diagnosed pregnant or culled from the herd

27. Proportion Not Pregnant

28. Results

29. Results Preg/Insemination

30. Ovsynch Advantages: • Elimination of estrus detection for first postpartum breeding • Timed AI results in conception rates similar to that of AI to a standing estrus Disadvantages: • Hormone Costs • Can not use on heifers

31. Ewe Estrus Synchronization Progestin • CIDR • vaginal pessary (sponge)

33. Use of Progestin in Sheep • If during the non-breeding season, induce follicular growth at time of CIDR removal • eCG (400 - 800 IU) • PG600 • Product designed for induction of puberty in gilts • contains 400 IU eCG and 200 IU HCG • Fertility in the breeding season is good • Use 1 ram / 10 ewes • Fixed time insemination at 48-52 hours using laproscopic technique

34. Ewe Estrus Synchronization PGF2a • Use in breeding season only • 2 injections of Lutalyse (20 mg ) 9 days apart • No effect if ewe anestrus

35. 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 • Seasonal • Decrease light to simulate fall • Give melatonin • Postpartum • If attempting to have 2 lamb crops, treat like induction of puberty Induction of Ovulation in Anestrous Ewes

36. Sow Estrus Synchronization PGF2a • 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 • Cost is $5 - $10/day

37. Sow Estrus Synchronization (cont.) Wean piglets • 3 - 6 days come into estrus

38. 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

39. Mare Estrus Synchronization PGF2a • 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

40. Mare Estrus Synchronization (cont.) • 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

41. Mare Estrus Synchronization (cont.) Progestins • Regumate • Oral progestin • Give 1 ml / 100 lbs body weight • Treatment • Feed daily for 12 - 14 days • On last day give PGF2a • 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

42. Induction of Ovulation in Anestrus Mares • Seasonal • Increase light exposure • 16 hours light / day (takes 30 - 60 days) • Postpartum • Breed at foal heat • Provide adequate nutrition and don’t see lactational anestrus