1. Reproductive Management in Beef Cattle Estrous Synchronization and AI
Richard F. Randle, DVM, MS
Beef Extension Veterinarian
University of Nebraska, Lincoln

2. U.S. Beef Cattle Inventory 2007 Census of Agriculture
Farms
Cattle
Farms with
No.
% of Total
1 to 49
607,708 79
9,413,294 29
50 to 99
84,253 11
5,656,207 17
100 to 499
67,210 9
12,475,448 38
500 to 999
4,413
0.5
2,861,202
1000 +
1,400
0.2
2,428,650 7
Total
764,984
100
32,834,801

3. 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
From NAHMS Survey, 1998

4. Reasons for not Using Reproductive Procedures
From NAHMS Survey, 1998

5. Meeting the Demand?
Having the correct genetics is becoming highly important to meeting industry demands
Correct genetics imperative to achieving premium dollars and enhancing returns on investment

6. A changing market structure that recognizes and rewards quality . . .
AI allows beef producers to use high accuracy proven sires …
BW and calving ease
Weaning and yearling growth
Carcass traits
Replacement females

7. AI provides the opportunity to make genetic progress and add value faster

8. Effective Estrus Synchronization Programs
Shorten the AI breeding season
Cows or heifers are in estrus during a predictable interval that facilitates AI
Reduce time and labor required to detect estrus
More cows and heifers becoming pregnant early during the breeding season
Result in older and heavier calves at weaning
Beneficial effects on the next breeding season
More days postpartum at the next breeding season
Replacement heifers will be older
The first question you may ask is what will estrus synchronization do for me? Effective synchronization programs will shorten the AI breeding season. Synchronized animals exhibit estrus at a predictable interval that facilitates AI thereby reducing time and labor required to detect estrus.
More animals conceive early in the breeding season. This results in older, heavier calves at weaning.
An additional benefit is the effects on the following breeding season. Animals conceiving early in the current breeding season have more days postpartum to prepare for rebreeding in the next season.

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

10. Estrous Cycle Length of the estrous cycle
Average 21 days (range 18 to 24 days)
Estrus (standing heat)
12 to 18 hours (range 8 to 30 hours)
Ovulation
Approximately 30 hours after the beginning of standing heat.

11. LH level LH surge onset of heat Progesterone Estradiol Luteal2 4 6 8 10 12 14 16 18 20
20/0
Progesterone
Day of
cycle
*Two full cycles and start of a third
Estradiol
Luteal
Follicular

12. LH level LH surge onset of heat Progesterone CL Estradiol Follicular2 4 6 8 10 12 14 16 18 20
20/0
Progesterone
Day of
cycle
*Two full cycles and start of a third CL
Estradiol
Follicular
Luteal
Follicular
Luteal

13. Corpus Luteum (CL) Growth and Regression2 4 6 8 10 12 14 16 18 20
Estrus
Day of the Estrous Cycle
Growth
Regression
Ovulation

14. Day of the Estrous Cycle
Prostaglandin F2 2 4 6 8 10 12 14 16 18 20
Day of the Estrous Cycle
PG regresses CL NO
YES
Estrus

15. Follicle Development Follicular Wave
Dominance
Regression
Growth
Selection
Next Recruitment
Recruitment
Follicle development occurs as a wave-like pattern consisting of “Recruitment”, “Selection”, “Growth”, “Dominance”, and “Regression” phases. Usually 2 to 4 follicular waves occur during the estrous cycle in cattle

16. Typical Pattern of Follicular Growth in Lactating Dairy Cows

17. Day of the Estrous Cycle
Follicle Development During the Estrous Cycle Example for 2 Follicular Waves
Day of the Estrous Cycle 2 4 6 8 10 12 14 16 18 20
Estrus
Ovulation
Length of the estrous cycle in cattle with 2 follicular waves is typically 18 to 20 days, slightly shorter than the estrous cycle with 3 follicular waves

18. LH level LH surge onset of heat Progesterone Estradiol Follicular2 4 6 8 10 12 14 16 18 20
20/0
Progesterone
Day of
cycle
*Two full cycles and start of a third
Estradiol
Follicular
Luteal
Follicular
Luteal

19. GnRH Induces ovulation Synchronizes follicular waves
Induces formation of a CL

20. How Does GnRH Induce Ovulation? GnRH, LH surge, and Ovulation
GnRH Injection
2 to 4
Hours after GnRH injection
24 to 30
Ovulation
LH Surge
GnRH induces LH surge within 2 to 4 hours
If cattle have large, healthy follicles, ovulation will be induced approximately 24 to 30 hours after GnRH injection without estrous behavior

21. How Does GnRH Induce Ovulation
How Does GnRH Induce Ovulation? Relationship between Follicular Waves and GnRH NO
YES
GnRH injection can induce ovulation in large, healthy follicles more than 10 mm in diameter
GnRH injection cannot induce ovulation in smaller follicles, less than 10 mm in diameter (premature) and regressing follicles (aged and not healthy)
Diameter of follicles are based on the data from ultrasonographic examination
> 10 mm

22. LH level LH surge onset of heat Progesterone Estradiol Follicular2 4 6 8 10 12 14 16 18 20
20/0
Progesterone
Day of
cycle
*Two full cycles and start of a third
Estradiol
Follicular
Luteal
Follicular
Luteal

23. Effect of a Progestin Heat Detect System Estrus Response
Synch Preg Rate
2-shot PG
241/452 = 57%
147/422 = 35%
MGA-PG 17 d
305/408 = 75%
220/408 = 54%
MGA-2 shot PG
327/348 = 93%
243/348 = 70%
MGA-PG 19d
161/208 = 78%
130/206 = 63%
MGA Select
275/313 = 88%
195/313 = 62%
7-11 Synch
142/155 = 93%
101/155 = 65%
Inclusion of a progestin can induce approximately 50% of non-cycling animals to cycle.

24. Effective Synchronization
Physiology and Biology
Synchronization of follicular waves
Induction of ovulation
Management of the CL lifespan
Initiation of estrous cyclicity

25. Effective Synchronization
Effective Products Available
GnRH
Cystorelin®, Factrel®, Fertagyl®, OvaCyst®
Prostaglandin
Estrumate®, In-Synch®, Lutalyse®, Prostamate®
Progestogens
MGA®, Eazi-Breed CIDR®

26. Resurgence in Research on Estrus Synchronization

27. Resurgence in Research on Estrus Synchronization
Ultimate goal is fixed-time AI with acceptable pregnancy rate!

28. Applied Reproductive Strategies in Beef Cattle
Beef Reproduction Task Force

29. Beef Reproduction Task Force
Review of the literature
Comparison of protocols
Beef Heifers
Heat detection protocols
Heat detection + timed AI protocols
Fixed-time AI protocols
Beef Cows

30. Comparison of Protocols Cows
Pregnancy Rateb
Heat Detection
Reportsa
No. of Cows
Range
Average
Select Synch 4
678
38-70 46
Select Synch + CIDR 8
595
42-85 51
Heat Detect &TAI 6
2048
31-89
1596
36-77 56
Fixed-Time AI
CO-Synch + CIDR 15
8124
43-80 59
aNumber of reports in published literature
bNumber pregnant to AI/total number treated

31. Comparison of Protocols Heifers
Pregnancy Rateb
Heat Detection
Reportsa
No. of Heifers
Range
Average
1 Shot PG
1(18 herds)
2700
------ 45
CIDR-PG 1
147
41-49 51
CIDR-PG (heat detect 3 d) 2
745
33-61 46
MGA-PG 6
2746
40-71 60
Heat Detect &TAI
Select Synch + CIDR
748
31-67 56 5
1905
48-64
Fixed-Time AI
CO-Synch + CIDR 10
1389
24-68 49
831
36-62
CIDR-Select
1069c
26-78 61
aNumber of reports in published literature
bNumber pregnant to AI/total number treated
cField data from 13 herds

32. Synchronization and Natural Service
Use a protocol that uses heat detection
Use smaller breeding pastures or lots to reduce travel
Use young mature bulls that are active known breeders
Make sure pecking order is established
Use bull to female ratio of 1:15 to 1:25

33. Synchronization and Natural Service5 45
Natural Service PG
1 Shot- PG
Treatment day
Bulls in
Non-synchronized
Synchronized
P-value n
2075
521
Calf birth date, julian day 86 85
0.23
Calf birth wt., lb 84 81
<0.001
Calved in 1st 21 days, % 61 73
Pregnant, % 95 94
0.48
Weaning wt., lb
483
503
Larson DM, Musgrave JA, Funston RN, University of Nebraska

34. Estrus Synchronization: Planning for Success

35. Plan the work. Work the plan!
Expectations for synchronization protocol.
Is the herd suited for synchronization protocol?
Labor needs .
Number of time through the chute.
Synchronization costs.
Handling facility capabilities.
Impact on calving distribution.
Record system.

36. Synchronization Expectations
Survey of recent results from today’s mainstay protocols
10 trials with 2,970 females from 34 different experimental groups
Average Synch preg. rate = 50.5% (8 to 66%)
26% of groups > 60% synch preg. rate
50% of groups 40% to 60% synch preg.rate
24% of groups < 40% synch preg. rate

37. Synchronization Expectations
Survey of recent results from today’s mainstay protocols
10 trials with 2,970 females from 34 different experimental groups
Average Synch preg. rate = 50.5% (8 to 66%)
26% of groups > 60% synch preg. rate
50% of groups 40% to 60% synch preg.rate
24% of groups < 40% synch preg. rate
Don’t expect great miracles.
Do expect variation.

38. Conception Rate Formula
(Cow fertility) X (Heat detection) X (Semen fertility)
X (AI technique)
Fail at any one of these and kiss success goodbye!!

39. Heat Detection Protocols
Heat Detection Rate
55%
60%
65%
70%
75%
80%
85%
90%
95%
Conception Rate
Pregnancy Rate
39%
42%
46%
49%
53%
56%
63%
67%

40. % of Cows Exhibiting Standing Estrus
Time of Day
% of Cows Exhibiting Standing Estrus
6am to noon
26.0%
Noon to 6pm
18.1%
6pm to midnight
26.9%
Midnight to 6am
29%
Perry, GA: South Dakota State University

41. Estrous Detection

42. Estrous Detection Detection aides Kmars Chinball markers Gomer bulls
Tail chalk
HeatWatch

43. Synchronization is an Investment
Labor
Facilities
Management
Dollars
In round numbers
Budgeted costs for synch programs can range from $20 to $40 per synchronized female

44. Is the Herd a Good Candidate?
Fertility rate
Calving distribution
Cow age
Body condition
Calving success
Replacement management

45. Replacement Management
Target Weight
Reproductive tract scores
Breed 20 days prior to cows

46. Cow Age Heifers take 20 days longer to cycle…
Johnson and Stevenson, KSU

47. Calving Distribution

48. Body Condition Score
CS = 4
CS = 6
Daryl Strohbehn, Iowa Beef Center

49. Body Condition Score CS = 4 CS = 6
A Barometer of the Nutrition Program
CS = 4
CS = 6
Major Influence on Start of Cyclicity
Daryl Strohbehn, Iowa Beef Center

50. Effect of BCS at Breeding on % Cycling
25%
CS 4-4.5
40-48%
CS 5-5.5
58-72%
CS 6
80% or more
Daryl Strohbehn, Iowa Beef Center

51. Effect of Body Condition Score at Calving on Postpartum Interval
100 80 60
Days Postpartum
88.5 40
69.7
59.4 20
51.7
30.6 3 4 5 6 7
Body Condition Score (BCS)
Adapted from Houghton et al., 1986

52. Labor Needs
Labor centers around feeding schedules, cattle roundup and handling through chute, heat detection, and AI schedules.
Shortage of labor at key times during the program poses critical threat to success.
Many times breeding programs compete with other farming routines.

53. Number of trips through the chute…
varies with the synchronization protocol
From IBC Estrus Synch Planner 2004

54. Cattle Handling Facility
A good facility is a necessity for a successful synchronized AI program
Think about cattle flow and efficiency
Think about safety
Think about location

55. Cattle Handling Facility
Location
Often located near wintering/calving facilities and nowhere near breeding pastures
Need to think about cattle management flow prior to synch program
May mean short dry lot periods or changes in pasture rotations

56. Do we know what to expect at calving from cows that conceive on the same day to the same sire?

57. Days relative to 285 d gestation due date; Bader et al., 20045 10 15 20 25
-13
-12
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 6 7 8 5 10 15 20 25
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4
A; Angus; +6.2 BW
, 20 d
B; Angus; +3.3 BW
, 17 d 5 10 15 20 25
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 10 15 20 25
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 6 7 8 9
C; Red Angus; –1.5 BW, 2 CED
, 15 d
D; Simmental; -0.6 BW, CE
, 19 d 25
B; Angus; +3.3 BW
, 17 d 20 15
% of AI calves born 10 5
-11
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6
Days relative to 285 d gestation due date; Bader et al., 2004

58. Summary For best success:
Current herd fertility >90% in day breeding season
Best female candidates calve in 1st 42 days of breeding season, thus at least 40 days before start of breeding season
1st calf heifers need additional recovery time following calving
Cows need minimum body condition score of 5

59. Protocol Compliance PGF MGA CIDR GnRH Numerous systems
Each with unique twist

60. Common Causes for Poor Results
Wrong system for the situation
More anestrous animals than expected
Cow protocol applied to heifers
Protocol not followed
Scheduling errors in timing of feed supplements and/or injections
Wrong product given

61. AMDUCA Animal Medicinal Drug Use Clarification Act
Defines extra-label drug use (ELDU)
Prostaglandin YES
Progestins YES
GnRH NO

62. Successful synchronization and AI programs require careful planning and attention to detail!