NEW OPPORTUNITIES TO SYNCHRONIZE NEW OPPORTUNITIES TO SYNCHRONIZE ESTRUS AND FACILITATE FIXED-TIME AIESTRUS AND FACILITATE FIXED-TIME AI

Division of Animal Sciences

University of Missouri-Columbia

July 6, 2005

DJ Patterson, MF Smith, and DJ Schafer

The current status of reproductive technology in the U.S.

beef cattle industry……

Reproductive TechnologiesReproductive Technologies Available or on the Horizon Available or on the Horizon

Estrus synchronization and AI Ultrasonography Sexed semen Embryo transfer In vitro production of embryos Transgenics (pharming) Cloning Male fertility

The U.S. Beef HerdThe 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

What’s happening in adoption of technology in the beef industry on a

global basis?

Total Domestic Sales of Beef SemenTotal Domestic Sales of Beef Semen

0

200000

400000

600000

800000

1000000

1200000

1400000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

1980

1982

1984

1986

1988

1990

1994

1996

1998

2000

1992

In the U.S. …...In the U.S. …...

Hough,, 2002

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

Import and Domestic Beef Semen SalesImport and Domestic Beef Semen Sales(units sold)(units sold)

1993

1,117,798

2003

1,025,116

-8% change

1993

1,874,996

2003

4,896,204

+161% change

From NAAB, 2003; ASBIA, 2003

Unless efforts are taken to implement change in the Unless efforts are taken to implement change in the

U.S. beef cattle industry, the products of our research U.S. beef cattle industry, the products of our research

and technology may be exported to more competitive and technology may be exported to more competitive

international markets . . . . . . (Patterson et al., 2000).international markets . . . . . . (Patterson et al., 2000).

Why are we here?Why are we here?

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).

From NAHMS Survey, 1998

36

14

20 21

39

13

20 19

34

19

14

22

0

10

20

30

40

%

Estrus synchronization Artificial insemination Pregnancy diagnosis

Reasons for not Using Reproductive Procedures

Time/labor Cost Complicated Other

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

A unique point in time for the A unique point in time for the U.S. beef industry………U.S. beef industry………

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………A unique point in time………

If we don’t impact use of AI among beef producers in the U.S. in the near future, will we ever?

The challenge of transferring The challenge of transferring

technology (estrus synchronization technology (estrus synchronization

and AI) to the private sector exceeds and AI) to the private sector exceeds

the task of research and development the task of research and development

of still newer technologies……….of still newer technologies……….

CollectivelyCollectively

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”

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

Objective: Development of highly effective & economical estrus synchronization programs

Peripubertal heifers Postpartum cows

Anestrus and estrous cycling

Excellent pregnancy rates

Products Currently Available Currently Available

Prostglandin Lutalyse, Estrumate, ProstaMate, In Synch,

EstroPlan GnRH

Cystorelin, Factrel, Fertagyl, OvaCyst Progestins

MGA CIDR

What We Know About MGA . . .What We Know About MGA . . .

ProgesteroneProgesteronePregn-4-ene-3, 20-dione

ProgesteroneProgesteronePregn-4-ene-3, 20-dione

OOCC

OO

CH3CH3

CH3CH3

CH3CH3

MGAMGA(melengestrol acetate)

6-methyl-17-alpha-acetoxy-16-methylene-pregn-4, 6-diene-3, 20-dione

MGAMGA(melengestrol acetate)

6-methyl-17-alpha-acetoxy-16-methylene-pregn-4, 6-diene-3, 20-dione

CC

OO

CH3CH3

OOCH3CH3 CH3

CH3

CH3CH3

CH3CH3

OO

OOCC

CH2CH2

What We Know About MGA . . . 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)

HEIFERS

Reproductive Tract Scores (RTS)Reproductive Tract Scores (RTS)

Adapted from Anderson et al., 1991

RTS

1

2

3

4

5

Length

15

18

22

30

> 32

Height

10

12

15

16

20

Width

8

10

10

12

15

Ovarian Measurement (mm)

Description

Infantile

Prepubertal

Peripubertal

Cycling

Cycling

Uterine horns

Immature < 20 mm diameter

No tone

20-25 mm diameterNo tone

20-25 mm diameterSlight tone

30 mm diametergood tone

> 30 mm diameter

Ovarian Structures

No palpable follicles

8 mmfollicles

8-10 mmfollicles

> 10 mm folliclesCL possible

CL present

Reproductive Tract Scores (RTS) Summary

RTS

1

2

3

4

5

n

61

278

1103

494

728

Weight (lb)

594a

620b

697c

733d

755d

Pelvic Width (cm)

10.9a

11.2a

11.4b

11.7c

11.7c

Pelvic Height (cm)

13.9a

14.1a

14.5b

14.7c

14.7c

Pelvic Area (cm2)

152a

158a

166b

172c

172c

Estrous Response

(%)

54a

66b

76c

83d

86d

Adapted from Patterson and Bullock, 1995

a, b, c, d Numbers with different superscripts within a column differ (P < 0.05)

Exposed 21-d PR2 42-d PR3 TPR4

RTS1 NS5

(n)SAI6

(n)NS(%)

SAI(%)

NS(%)

SAI(%)

NS(%)

SAI(%)

1 8 55 38a 42a 63c 55c 63e 60e

2 108 661 31a 52b 54c 68d 75e 82e

3 336 3320 41a 58b 65c 74d 82e 87f

4 322 3629 48a 62b 72c 77d 91e 87f

5 242 2835 50a 64b 74c 80d 88e 88e

TOT 1016 10500 44a 61b 68c 73d 85e 87e

a,b Means within rows for 21-d PR with different superscripts differ (P < .05)c,d Means within rows for 42-d PR with different superscripts differ (P < .05)e,f Means Within rows for TPR with different superscripts differ (P < .05)From Randle and Patterson, 2005

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

MGA (14 days)

11 14 16 20 14 16 20 31 33 36 31 33 36

PGPG

Synchronizedestrus

Treatment days

Estrus

Brown et al., 1988

MGA-PG14-19 d

Improved estrous responseImproved estrous response More heifers in heatMore heifers in heat

Similar fertilitySimilar fertility No change in conception or pregnancy rateNo change in conception or pregnancy rate

Improved synchronyImproved synchrony More heifers in heat in a shorter timeMore heifers in heat in a shorter time

(Deutscher et al., 2000; Lamb et al., 2000)

MGA (14 days)

1 14 33

PG

Wood et al., 2001

MGA-PG

Treatment days

MGA (14 days)

1 14 26 33

PGGnRHMGA Select

0

5

10

15

20

25

30

35

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

Fol

licl

e d

iam

eter

(m

m)

ESTRUSESTRUS

PG

Wood et al., 2001

0

5

10

15

20

25

30

35

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

Fol

licl

e d

iam

eter

(m

m)

ESTRUSESTRUS

PGGnRH

Wood et al., 2001

When to Add GnRH When to Add GnRH to an MGA-PG Protocol for Heifersto an MGA-PG Protocol for Heifers

Consideration of . . . . Age Weight Reproductive tract score (RTS)

Pubertal status

Wood et al., 2000; Kojima et al., 2001

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

1 14 26 33

MGA (14 days)

1 14 23 30

Treatment day

.. .. 12 days .. .. .. .. 7 days .. ..

.. .. 9 days .. .. .. .. 7 days .. ..

GnRH

GnRH

PG

PG

Experimental ProtocolsExperimental Protocols

Kojima et al., 2004

CIDR (14 days)

MGA Select

14-d CIDR

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

0 1 2 3 4 5+

Days after PG

% o

f H

eife

rs I

nse

min

ated

Summary for Timing of AISummary for Timing of AI

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)

0

10

20

30

40

50

60

70

80CIDR (n = 177)

MGA (n = 175)

0% 1%

10% 15%

69%

53%

5%

10%16%

21%PG

Kojima et al., 2004

112/177 (63 %)a

83/175 (47 %)b

195/352 (55 %)

AI Pregnancy

a, b P = 0.01+ 16 %

CIDR

MGA

Total

154/177 (87 %)

147/175 (84 %)

301/352 (86 %)

Estrous Response

Estrous Response, AI Pregnancy, and Final Estrous Response, AI Pregnancy, and Final Pregnancy RatesPregnancy Rates

+ 3 %Diff.

164/177 (93 %)

159/175 (91 %)

323/352 (92 %)

FinalPregnancy

+ 2 % Kojima et al., 2004

SummarySummary

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

COWS

How do MGA-based protocols perform in synchronizing estrus in mixed populations of postpartum

beef cows? (estrous cycling and anestrus)

Precise control of the bovine estrous cycle requires the synchronization of both luteal and follicular functions.

Protocols

1 14 26 33

MGA (14 days)

Treatment day

MGA Select

MGA

7-11 Synch

1 7 11 18

PGGnRH

PGGnRH

PG

Kojima et al., 2000; Wood et al., 2001

These protocols were hypothesized to……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

These protocols were hypothesized to……These protocols were hypothesized to……

Reduce the period of time required to detect estrus

Facilitate fixed-time AI

How do MGA Select and 7-11 Synch How do MGA Select and 7-11 Synch compare on the basis of synchronized compare on the basis of synchronized

estrus and pregnancy rates in postpartum estrus and pregnancy rates in postpartum beef cows with AI performed on the basis beef cows with AI performed on the basis

of of detecteddetected estrusestrus??

MGA Select vs. 7-11 SynchMGA Select vs. 7-11 SynchAI performed after detected estrusAI 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

0

5

10

15

20

25

30

35

40

45

0 12 24 36 48 60 72 84 96 108 120 132 144 NR

Time after PG, h

Co

ws

in e

stru

s, n

oMGA Select

7-11 Synch

Stegner et al., 2004

Pregnancy rateNo. (%)

MGA SelectPatterson et al., 2001 67/103 65Patterson et al., 2002 67/101 66Stegner et al., 2003 61/109 56Combined total 195/313 62

7-11 Synch Kojima et al., 2001 30/44 68Stegner et al., 2003 71/111 64Combined total 101/155 65

Pregnancy Rates of Cows Inseminated Pregnancy Rates of Cows Inseminated after Detected Estrusafter Detected Estrus

How do MGA Select and 7-11 Synch How do MGA Select and 7-11 Synch compare on the basis of pregnancy rates in compare on the basis of pregnancy rates in

postpartum beef cows inseminated at postpartum beef cows inseminated at predeterminedpredetermined fixedfixed timestimes??

MGA Select

72 hr

80 hr

72 hr

48 hr

Time of AI after PG

64%

50% Stegner et al., 2003

61%Perry et al., 2002

46%Stevenson et al., 2003

Pregnancy rate

7-11 Synch

61%60 hrUnpublished data., 2002

52%

59%

48 hr

60 hrKojima et al., 2003

63%60 hrKojima et al., 2003

63%60 hrKojima et al., 2002

72%48 hrHixon et al., 2001

Pregnancy rate

Time of AI after PG

Bader et al. (2004) compared pregnancy rates resulting from fixed-time AI among suckled beef cows assigned to the MGA Select or 7-11 Synch protocols.

ProtocolsProtocols

1 14 26 33 … … … 72 hr

MGA (14 days)

Treatment day

MGA Select

MGA

7-11 Synch

1 7 11 18 … … 60 hr

PG

PGGnRH

PG

AI

GnRH

GnRH

GnRH

AI

Bader et al., 2004

Location

Days

postpartum

Body

condition score Estrous cycling

No. %

1 50 ± 1.0a 5.8 ± 0.1a 64/208 31a

2 39 ± 1.3b 5.8 ± 0.1a 31/122 25a,b

3 36 ± 1.5b 5.4 ± 0.1b 18/92 20b

Combined 42 d 5.7 113/422 27

Days postpartum, body condition score, and estrous-cycling status prior to initiation of synchronization treatments

a,b(P < 0.05)

Bader et al., 2004

Location Treatment Fixed-time AI Final

No. % No. %

17-11 Synch 64/104 62 95/104 91

MGA Select 68/104 65 101/104 97

27-11 Synch 34/60 57 57/59 97

MGA Select 43/62 69 60/62 97

37-11 Synch 30/45 67 43/45 96

MGA Select 31/47 66 42/47 89

Combined7-11 Synch 128/209 61 195/208 94

MGA Select 142/213 67 203/213 95

Fixed-time AI and final pregnancy rates

Bader et al., 2004

MGA Select 7-11 Synch

Cycling Anestrus Cycling Anestrus

Location No. Preg % No. Preg % No. Preg % No Preg %

1 20/30 67 48/74 65 24/34 71 40/70 57

2 12/16 75 31/46 67 9/15 60 25/45 56

3 6/8 75 25/39 64 8/10 80 22/35 63

Combined 38/54 70 104/159 65 41/59 69 87/150 58

Fixed-time AI pregnancy rate based on pretreatment estrous cyclicity status

Bader et al., 2004

Pros and Cons

MGA Select - effective in mixed - treatment length populations - MGA intake - synchrony of estrus - fertility after treatment 7-11 Synch - effective in mixed - multiple populations animal handlings - exceptional synchrony - drug costs of estrus - MGA intake - fertility after treatment - treatment duration

Advantages Disadvantages

Pregnancy rateNo. (%)

7-11 Synch Detected estrus 101/155 65Fixed-time AI 446/728 61

MGA SelectDetected estrus 195/313 62Fixed-time AI 281/436 64

Pregnancy rates after AI based on detected estrus Pregnancy rates after AI based on detected estrus or at predetermined fixed timesor at predetermined fixed times

Implications

This sequential approach to estrous cycle control (progestin-GnRH-PG) effectively synchronizes estrus with resulting high fertility among mixed populations of estrous cycling and anestrous postpartum beef cows.

How do MGA- and CIDR-based protocols compare on the basis of

pregnancy rates in postpartum beef cows inseminated at

predetermined fixed times?

1 14 26 33………

0 7……….

MGA (14 d)

GnRH

MGA Select vs. CO-Synch + CIDRMGA Select vs. CO-Synch + CIDRSchafer, 2005

Treatment day

PG

GnRH PG

GnRH

AI

GnRH

AI

CIDR (7 d)

Timing of InseminationTime of AI Pregnancy

Protocol after PG rate MGA SelectStevenson et al., 2003 48 h 46%Perry et al., 2002 72 h 61%Bader, 2004 72 h 67%Stegner et al., 2004 72 h 64%

80 h 50%

CO-Synch + CIDRLamb et al., 2000 48 h 56%

48 h 56%Bremer et al., 2004 54 h 67%

66 h 71%

Larson et al., 2004 60 h 54%

1 14 26 33 …… 72h

0 7 …... 66h

MGA (14 d)

GnRH

MGA Select vs. CO-Synch + CIDRMGA Select vs. CO-Synch + CIDRSchafer, 2005

Treatment day

CIDR (7 d)

PG

GnRH PG

AI

GnRH

GnRH

AI

Experimental ProceduresExperimental ProceduresSchafer, 2005Schafer, 2005

Animals: Crossbred, suckled, beef cows (n = 650) at four locations were assigned to treatment within age groups by calving date and BCS

Experimental ProceduresExperimental ProceduresSchafer, 2005Schafer, 2005

Four different AI sires were used Location 1 = 3 Location 2 = 1 Location 3 = 1 Location 4 = 1

One of the sires that was used at location 1 was the same sire used at Locations 3 & 4

Experimental ProceduresExperimental ProceduresSchafer, 2005Schafer, 2005

Cows were exposed to fertile bulls 14 d after AI

Pregnancy rate to fixed-time AI was determined with ultrasound 40 – 45 d after insemination

Location

Days

postpartum

Body

condition score

Estrous cycling

No. %

1 46 5.7 112/210 53

2 33 6.0 63/158 40

3 44 5.3 31/88 35

4 43 5.3 156/194 80

Combined 42 d 5.5 362/650 56

Number of cows at each location, DPP, BCS, and estrous-cycling status prior to initiation of synchronization treatments

(Schafer, 2005)

Fixed-time AI pregnancy rates between treatments and among locations (Schafer, 2005)

Location Treatment Fixed-time AI

No. %

1MGA Select 70/106 66

CO-Synch+CIDR 67/104 64

2MGA Select 53/80 66

CO-Synch+CIDR 56/78 72

3MGA Select 26/45 58

CO-Synch+CIDR 29/43 67

4MGA Select 52/96 54

CO-Synch+CIDR 62/98 61

Pregnancy rates to fixed-time AI Pregnancy rates to fixed-time AI Schafer, 2005Schafer, 2005

Pregnancy rate

Treatment No. %

MGA Select 201/327 61

CO-Synch+CIDR 214/323 66

MGA® Select CO-Synch+CIDR

Cycling Anestrus Cycling Anestrus

Location No. Preg % No. Preg % No. Preg % No Preg %

1 38/62 61 32/44 73 30/50 60 37/54 69

2 20/29 69 33/51 65 25/34 74 31/44 70

3 11/16 69 15/29 52 8/15 53 21/28 75

4 41/78 53 11/18 61 50/78 64 12/20 60

Combined 110/185 59 91/142 64 113/177 64 101/146 69

Fixed-time AI pregnancy rate based on pretreatment estrous cyclicity status (Schafer, 2005)

Conclusions Conclusions Schafer, 2005Schafer, 2005

The results from this experiment demonstrate that comparable pregnancy rates to fixed-time AI can be achieved using the MGA Select or CO-Synch+CIDR protocols to synchronize estrus in postpartum beef cows.

Do we know what to expect at calving Do we know what to expect at calving from cows that conceive on the same from cows that conceive on the same

day to the same sire?day to the same sire?

0

5

10

15

20

25

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5

0

5

10

15

20

25

-11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 40

5

10

15

20

25

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9

0

5

10

15

20

25

-11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6

Days relative to 285 d gestation due date; Bader et al., 2004

% o

f A

I ca

lves

bor

n

0

5

10

15

20

25

-13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8

A; Angus; +6.2 BW272-292, 20 d

B; Angus; +3.3 BW275-292, 17 d

C; Red Angus; –1.5 BW, 2 CED274-289, 15 d

D; Simmental; -0.6 BW, +14.8 CE275-294, 19 d

B; Angus; +3.3 BW274-291, 17 d

0

2

4

6

8

10

12

14

16

18

20

-14 -12 -10 -8 -6 -4 -2 0 2 40

2

4

6

8

10

12

14

16

18

20

-10 -8 -6 -4 -2 0 2 4 6 80

2

4

6

8

10

12

14

16

18

20

-11 -9 -7 -5 -3 -1 1 3 5 7

0

2

4

6

8

10

12

14

16

18

20

-12 -8 -6 -3 0 3 6 9 12 150

2

4

6

8

10

12

14

16

18

20

-13 -11 -9 -7 -5 -3 -1 1 3 5 7 90

2

4

6

8

10

12

14

16

18

20

-10 -8 -6 -4 -2 0 2 4 6 8

Location 1; Sire A (Angus) BW EPD -0.3; CED = +11 Range 271-290 Mean = 281

Location 1; Sire B (Angus) BW EPD +3.5; CED = +6 Range 275-292 Mean = 281

Location 1; Sire C (Angus) BW EPD -1.1; CED = +11 Range 274-287 Mean = 281

Location 2; Sire D (Red Angus) BW EPD +2.3; CED = -2 Range 273-300 Mean = 283

Location 3; Sire B (Angus) BW EPD +3.5; CED = +6 Range 272-294 Mean = 283

Location 4; Sire B (Angus) BW EPD +3.5; CED = +6 Range 275-294 Mean = 284

0

2

4

6

8

10

12

271 274 277 280 283 286 289 292 295 298

Day of Gestation

% o

f A

I si

red

cal

ves

Location 1; Sire A Location 1; Sire B Location 1; Sire C

Location 2; Sire D Location 3; Sire B Location 4; Sire B

Calving Distribution of AI sired calves (Schafer et al., 2005)

Consider the impact of estrus synchronization on calving distribution………

Opportunities for increasing profits lie in managing females from the later calving intervals forward toward the first and second calving intervals.

High production herds see 61% of the calves born by day 21, 85% by day 42 and 94% by day 63.

Hughes, 2005

First 15 d First 30 d0

102030405060708090

100 MGA Select7-11 Synch

Calving period

Cow

s ca

lvin

g, %

Stegner et al., 2004

0

1

2

3

4

5

6

7

8

%

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77

Day of calving season

Calving distribution for locations 1, 2, & 3 (Schafer, 2005)

Cumulative Calf % by:

day 15 = 64%

day 21 = 70%

day 30 = 77%

day 42 = 91%

0102030405060708090

100

2004 2005

MU Forage Systems Research Center cumulative calf crops

0

10

20

30

40

50

60

70

80

90

100

1 16 31 46

Day of calving season

Per

cen

tag

e

Natural Service (3 years; n = 526) Estrus Detection & AI (5 years; n = 1040)Fixed-time AI (2 years; n = 397)

Cumulative calf crops (MU Thompson Farm) for the first 46 days over 10 calving seasons

Conclusions and ImplicationsConclusions and Implications

Estrous response and fertility in postpartum beef cows after treatment with various estrus synchronization protocols.

Treatment Estrous response Pregnancy rate

AI based on

detected estrus No. % No. %

* DeJarnette and Wallace

2 shot PGSelect Synch*MGA-PGMGA Select7-11 Synch

241/422 57353/528 67305/408 75275/313 88142/155 92

147/422 35237/528 45220/408 54195/313 62101/155 65

Fixed-time AIMGA Select7-11 SynchCO-Synch + CIDR

482/763 63446/728 61214/323 66

Estrous response and fertility in postpartum beef cows after treatment with various estrus synchronization protocols.

Treatment Estrous response Pregnancy rate

AI based on detected estrus No. % No. %

* DeJarnette and Wallace

2 shot PGSelect Synch*MGA-PGMGA Select7-11 Synch

241/422 57353/528 67305/408 75275/313 88142/155 92

147/422 35237/528 45220/408 54195/313 62101/155 65

Fixed-time AIMGA Select7-11 SynchCO-Synch + CIDR

482/763 63446/728 61214/323 66

CO-Synch + CIDR Results (FTAI @ 66 hr after PG)

Herd (Year) No. Pregnant Total No. Percentage

1 (F03) 41 51 80

2 (S04) 67 104 64

3 (S04) 56 78 72

4 (S04) 29 43 67

5 (S04) 52 96 63

6 (S04) 60 90 67

7 (F04) 31 48 65

8 (F04) 87 143 61

9 (F04) 61 100 61

10 (F04) 44 69 63

11 (F04) 68 111 61

12 (F04) 47 60 78

13 (S05 143 224 64

Total 786 1217 65

• Research is underway to develop new protocols for heifers that will facilitate fixed-time AI ….

• The technology now exists to successfully inseminate postpartum beef cows at predetermined fixed times with resulting high pregnancy rates . . . . . . . . .

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

AcknowledgementsAcknowledgementsFaculty, Students, & StaffFaculty, Students, & Staff

Jon Bader Dr. George Perry Roger Eakins Daniel SchaferDr. Mark Ellersieck Jon SchrefflerFreddie Kojima Dr. Mike SmithDr. Matthew Lucy Jacob StegnerDavid McAtee Stacey Wood

(Follis)

AcknowledgementsAcknowledgements

Research Support Cooperators

Select Sires, Inc. 4-M Ranch

KABA/Select Sires, Inc. John Ranch

ABS Global Jim Wallis Farms

Merial Jim Clement, DVM

Pfizer Animal Health SEMO University

USDA-NRI MFA, Inc.

MU Farms & Centers

AcknowledgementsAcknowledgements

Beef Reproduction Leadership Team

AI industry

Pharmaceutical industry

Veterinary practitioners

North Central Region Bovine Reproduction Task Force