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NEW OPPORTUNITIES TO SYNCHRONIZE ESTRUS AND FACILITATE FIXED-TIME AI

NEW OPPORTUNITIES TO SYNCHRONIZE ESTRUS AND FACILITATE FIXED-TIME AI. DJ Patterson, MF Smith, and DJ Schafer. Division of Animal Sciences University of Missouri-Columbia July 6, 2005. The current status of reproductive technology in the U.S. beef cattle industry…….

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NEW OPPORTUNITIES TO SYNCHRONIZE ESTRUS AND FACILITATE FIXED-TIME AI

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  1. NEW OPPORTUNITIES TO SYNCHRONIZE ESTRUS AND FACILITATE FIXED-TIME AI DJ Patterson, MF Smith, and DJ Schafer Division of Animal Sciences University of Missouri-Columbia July 6, 2005

  2. The current status of reproductive technology in the U.S. beef cattle industry……

  3. Reproductive Technologies Available or on the Horizon • Estrus synchronization and AI • Ultrasonography • Sexed semen • Embryo transfer • In vitro production of embryos • Transgenics (pharming) • Cloning • Male fertility

  4. The U.S. Beef Herd • 69% of cow-calf enterprises are secondary income sources • 50% of producers report an established breeding season of specific duration • 34% of beef herds are routinely pregnancy checked • 10% of beef cattle enterprises utilize AI

  5. What’s happening in adoption of technology in the beef industry on a global basis?

  6. 1984 1986 1980 1988 1982 1998 2000 1990 1992 1994 1996 In the U.S. …... Total Domestic Sales of Beef Semen Hough,, 2002

  7. Comparison of AI Use In Beef Cattle (U.S. vs. Brazil)

  8. Import and Domestic Beef Semen Sales(units sold) 1993 1,117,798 2003 1,025,116 1993 1,874,996 2003 4,896,204 +161% change -8% change From NAAB, 2003; ASBIA, 2003

  9. Unless efforts are taken to implement change in the U.S. beef cattle industry, the products of our research and technology may be exported to more competitive international markets . . . . . . (Patterson et al., 2000).

  10. Why are we here?

  11. Artificial insemination and estrus synchronization are generally regarded as the most important and applicable of all available biotechnologies to the beef cattle industry (Seidel, 1995).

  12. From NAHMS Survey, 1998

  13. Improvements in methods to synchronize estrus create the opportunity to significantly expand the use of AI in the U.S. cowherd ………………….

  14. Availability of tools and understanding of methods to control the estrous cycle in cattle A changing market structure that recognizes and rewards quality A unique point in time for the U.S. beef industry………

  15. If we don’t impact use of AI among beef producers in the U.S. in the near future, will we ever? A unique point in time………

  16. The challenge of transferring technology (estrus synchronization and AI) to the private sector exceeds the task of research and development of still newer technologies……….

  17. Collectively • Adopt common terminology regarding the various estrus synchronization protocols • Identify and agree upon short lists of protocols • heifers and cows • heat detect and AI vs fixed-time AI • Work to overcome the attitude of “What will this cost me?” ….to… “ I’m willing to make an investment in my herd”

  18. Effective Estrus Synchronization Programs for Beef Cattle • Facilitate AI & ET • Reduce time required to detect estrus • Cycling females conceive earlier in the breeding period • Induce cyclicity in peripubertal heifers and anestrous postpartum cows

  19. Objective: Development of highly effective & economical estrus synchronization programs • Peripubertal heifers • Postpartum cows • Anestrus and estrous cycling • Excellent pregnancy rates

  20. Products Currently Available • Prostglandin • Lutalyse, Estrumate, ProstaMate, In Synch, EstroPlan • GnRH • Cystorelin, Factrel, Fertagyl, OvaCyst • Progestins • MGA • CIDR

  21. What We Know About MGA . . .

  22. CH3 O C CH3 CH3 O Progesterone Pregn-4-ene-3, 20-dione CH3 O C O CH3 O C CH3 CH2 CH3 O MGA (melengestrol acetate) 6-methyl-17-alpha-acetoxy-16-methylene-pregn-4, 6-diene-3, 20-dione CH3

  23. What We Know About MGA . . . • Induces puberty in beef heifers (Imwalle et al., 1998) • Prevents expression of behavioral estrus (Zimbelman and Smith, 1966; Imwalle et al., 2002) • Blocks the preovulatory surge of LH (Imwalle et al., 2002) • Blocks ovulation (Zimbelman and Smith, 1966; Imwalle et al., 2002)

  24. HEIFERS

  25. Ovarian Measurement (mm) Ovarian Structures No palpable follicles 8 mmfollicles 8-10 mmfollicles > 10 mm follicles CL possible CL present DescriptionInfantilePrepubertalPeripubertal Cycling Cycling RTS123 4 5 Uterine hornsImmature < 20 mm diameterNo tone20-25 mm diameterNo tone20-25 mm diameterSlight tone30 mm diametergood tone > 30 mm diameter Length151822 30 > 32 Height101215 16 20 Width81010 12 15 Reproductive Tract Scores (RTS) Adapted from Anderson et al., 1991

  26. Reproductive Tract Scores (RTS) Summary Pelvic Height (cm) 13.9a 14.1a 14.5b 14.7c 14.7c Pelvic Width (cm) 10.9a 11.2a 11.4b 11.7c 11.7c Pelvic Area (cm2) 152a 158a 166b 172c 172c Estrous Response (%) 54a 66b 76c 83d 86d Weight (lb) 594a 620b 697c 733d 755d RTS 1 2 3 4 5 n 61 278 1103 494 728 a,b, c, d Numbers with different superscripts within a column differ (P < 0.05) Adapted from Patterson and Bullock, 1995

  27. Comparison of reproductive performance in herds using natural service or synchronization and AI on replacement heifers by RTS

  28. Synchronized Estrus estrus PG MGA (14 days) 1 14 16 20 31 33 36 Treatment days Brown et al., 1988

  29. MGA-PG14-19 d • Improved estrous response • More heifers in heat • Similar fertility • No change in conception or pregnancy rate • Improved synchrony • More heifers in heat in a shorter time (Deutscher et al., 2000; Lamb et al., 2000)

  30. GnRH PG MGA (14 days) 1 14 26 33 Treatment days MGA-PG PG MGA (14 days) 1 14 33 MGA Select Wood et al., 2001

  31. 35 30 PG 25 20 Follicle diameter (mm) 15 10 5 ESTRUS 0 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Day of treatment Wood et al., 2001

  32. 35 30 GnRH PG 25 20 Follicle diameter (mm) 15 10 5 ESTRUS 0 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Day of treatment Wood et al., 2001

  33. When to Add GnRH to an MGA-PG Protocol for Heifers • Consideration of . . . . • Age • Weight • Reproductive tract score (RTS) • Pubertal status Wood et al., 2000; Kojima et al., 2001

  34. How do MGA- and CIDR-based protocols compare in heifers?

  35. Experimental Protocols MGA Select PG GnRH MGA (14 days) .. .. 12 days .. .. .. .. 7 days .. .. 1 14 26 33 14-d CIDR GnRH PG CIDR (14 days) .. .. 9 days .. .. .. .. 7 days .. .. 1 14 23 30 Treatmentday Kojima et al., 2004

  36. Experimental Procedures • 352 yearling crossbred beef heifers at three locations Location 1 n = 154 (Southeast Missouri) Location 2 n = 113 (North Dakota) Location 3 n = 85 (North central Missouri) • Heifers were assigned to one of two treatments (MGA or CIDR) by age and weight Kojima et al., 2004

  37. CIDR (n = 177) MGA (n = 175) Summary for Timing of AI 80 69% 70 60 53% 50 % of Heifers Inseminated 40 30 21% PG 20 16% 15% 10% 10% 10 5% 1% 0% 0 0 1 2 3 4 5+ Days after PG • No treatment x location effect (P > 0.10); therefore, data were pooled • Distribution of AI dates were different between MGA- and CIDR-treated heifers (P < 0.02) Kojima et al., 2004

  38. Estrous Response, AI Pregnancy, and Final Pregnancy Rates Estrous Response AI Pregnancy FinalPregnancy 154/177 (87 %) 112/177 (63 %)a 164/177 (93 %) CIDR 147/175 (84 %) 83/175 (47 %)b 159/175 (91 %) MGA 301/352 (86 %) 195/352 (55 %) 323/352 (92 %) Total a, b P = 0.01 + 3 % Diff. + 16 % + 2 % Kojima et al., 2004

  39. Summary • In yearling beef heifers: • CIDR-GnRH-PG improved synchrony of estrus compared with MGA Select • CIDR-GnRH-PG improved AI pregnancy rate over MGA Select Kojima et al., 2004

  40. COWS

  41. How do MGA-based protocols perform in synchronizing estrus in mixed populations of postpartum beef cows?(estrous cycling and anestrus)

  42. Precise control of the bovine estrous cycle requires the synchronization of bothlutealand follicularfunctions.

  43. PG Protocols MGASelect GnRH PG MGA (14 days) 1 14 26 33 7-11 Synch GnRH PG MGA 1 7 11 18 Treatment day Kojima et al., 2000; Wood et al., 2001

  44. These protocols were hypothesized to…… • Improve estrous response and pregnancy rates during the synchronized period • Effectively synchronize estrus in estrous cycling cows • Induce cyclicity in anestrous cows • Prevent short cycles among anestrous cows induced to ovulate

  45. These protocols were hypothesized to…… • Reduce the period of time required to detect estrus • Facilitate fixed-time AI

  46. How do MGA Select and 7-11 Synch compare on the basis of synchronized estrus and pregnancy rates in postpartum beef cows with AI performed on the basis of detectedestrus?

  47. MGA Select vs. 7-11 SynchAI performed after detected estrus • No difference in estrous response • Improvement in synchrony of estrus among 7-11 Synch treated cows (P < 0.01) • No difference in synchronized conception or pregnancy rates • No difference in final pregnancy rate Stegner et al., 2004

  48. 45 MGA Select 40 7-11 Synch 35 30 25 Cows in estrus, no 20 15 10 5 0 0 12 24 36 48 60 72 84 96 108 120 132 144 NR Time after PG, h Stegner et al., 2004

  49. Pregnancy Rates of Cows Inseminated after Detected Estrus Pregnancy rate No.(%) MGA Select Patterson et al., 2001 67/103 65 Patterson et al., 2002 67/101 66 Stegner et al., 2003 61/109 56 Combined total 195/313 62 7-11 Synch Kojima et al., 2001 30/44 68 Stegner et al., 2003 71/111 64 Combined total 101/155 65

  50. How do MGA Select and 7-11 Synch compare on the basis of pregnancy rates in postpartum beef cows inseminated at predeterminedfixedtimes?

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