1. Replacement Heifer Management: A coordinated management concept
Richard F. Randle, DVM, MS
Beef Extension Veterinarian
University of Nebraska-Lincoln

2. Economic and Genetic Importance of Various Traits
Adapted from (A)Willham, 1973; (B)Melton, 1995

3. Heritability of Reproductive Traits
From Dearborn et al., 1973; Laster et al., 1979

4. Reproductive Losses (%)
Adapted from Bellows and Short, 1990; Wiltbank, 1990

5. Adapted from Bellows and Short, 1990; Wiltbank, 1990
Bred Replacements
Adapted from Bellows and Short, 1990; Wiltbank, 1990

6. Replacement Heifers Calve by 24 months of age with minimum problems
Give birth to and raise a vigorous, healthy calf
Successfully re-breed

7. Importance of Replacement Heifers
Dictates future performance of herd
Where will the herd be in 5 years?
Substantial investment before any return
30 months minimum before sale of 1st calf
Highest potential for reproductive problems
Dystocia, calf survival, rebreeding

8. Courtesy of Dr. Jeff Ondrak GPVEC

9. Postpartum period; lactation
Breeding: Conception
Puberty
Gestation
Rebreeding
Weaning
Parturition
Postpartum period; lactation

10. Process….
Selection
Development
Procedures
Monitor

11. Heifer Selection Replacement rate - 10% to 20% Select 10% to 20% more
Age, Size
Conformation
Dam performance

12. Heifer Selection Scenarios
Retain all heifers and breed
Retain all heifers born in 1st half of calving
Remove top and bottom 10% by size or weight
Retain all heifers born in 1st 30 days
Calf performance data
Dam performance data

13. Heifer Development Grow Attain puberty Determine breeding strategy
Bull selection

14. Puberty Function of… Age Weight 10 to 12 months Breed influence
55% to 65% of mature weight

15. Pregnancy Rates of Heifers Bred at Pubertal or Third Estrus
% Pregnant
Pubertal 57
Third 78
from Byerley et al., 1987

16. Heifers Optimum Growth Rate for Breeding Herd Replacement Heifers
Adapted from Fox et al., 1988

17. Target Weight
Determine breeding date based on when you want them to calve
Determine the target weight for breeding
Determine the number of days from weaning to breeding
Determine ADG

18. Target Weight Breeding Weight - Weaning Weight = ADG
Breeding Date - Weaning Date
= ADG

19. Breeding Strategy
In order for heifer to calve by 24 months of age she must conceive by 15 months of age

20. Breeding Strategy
In order for a cow to calve every 365 days she must conceive by 80 days post calving
Uterine involution
Return to cycling
Cows average 40 to 60 days
Heifers average 60 to 80 days

21. Breeding Strategy
Breed heifers to calve 2 to 3 weeks before the cow herd
Calve the second time in line with the cow herd

22. Breeding Strategy Natural Service Synchronization
Artificial Insemination

23. Procedures
Health
Pre-breeding
Pregnancy Examination
Pre-calving

24. Health and Vaccination Program
Advice and guidance of veterinarian
Proper product use
Timing
Starts at or before weaning
Prebreeding, Pregnancy Exam, Pre-calving
Focus on diseases that cause reproductive losses and reduced reproductive performance
IBR, BVD, Lepto, Brucella, Campylobacter, Trichomoniasis, Neonatal diarrhea, Parasites….

25. Pre-breeding Evaluation
Evaluate weaning to pre-breeding development
Average age of the group should be 12.5 to 13.5 months ( days)
Performed 30 to 60 days prior to scheduled breeding program

26. Pre-breeding Examination
Weight and body condition
80 % at 55% of mature body weight
Pelvic measurement
150 cm2 or greater
Reproductive tract score
50% or greater cycling (RTS 4, 5)
Conformation and structural soundness
Health

27. 65%
55%

28. Reproductive Tract Scores
From Anderson et al., 1991

29. Identify abnormally small or shaped pelvis

30. Neonatal Exposure to Progesterone & Estradiol on Reproductive Tract in Beef Heifers
aData were collected from cyclic adult beef heifers on Day 12 of induced estrous cycle.
Group means (n = 5) and SEM are presented.
bTreated heifers received a single Synovex-C implant sc on designated day of life. Controls were untreated.
cWet weight.
d,e,f(P<0.01), g,,h(P<0.02), i,j(P<0.09): Means within a row with different superscripts differ.
Adapted from Fox et al., 1988

31. Pre-breeding Individual and Summary Data
Used to evaluate success, identify potential problems and institute management changes
Pre-breeding analysis
% cycling, nutritional status, structural soundness
Review breeding management

32. Pregnancy Examination
Perform prior to 120 days gestation
determine fetal age
Weight and body condition
Distinguish AI pregnancies from natural service pregnancies
withhold clean-up bulls 2 weeks
Health

33. Pregnancy Individual and Summary Data
Used to evaluate success and identify management changes for improvement
Pregnancy rates, pregnancy histograms, synchronization response, AI conception rates, synchronized pregnancy rates

34. Pre-calving Examination
Perform 30 to 45 days before calving
Weight and body condition
85% of mature weight
BCS of 6
Health

35. Adapted from Patterson and Bullock, 1995
Reproductive Summary
Adapted from Patterson and Bullock, 1995

36. Reproductive Performance by Reproductive Tract Score
RTS
Exposed
Pregnant
Open
Preg Rate 1 75 46 29 61 2
1055
854
201 81 3
4504
3911
593 87 4
4912
4322
590 88 5
3675
3261
414 89
TOTALS
14221
12394
1827
Randle RF, Patterson DJ, 2005

37. Reproductive Performance by Reproductive Tract Score
1st 21 Days
2nd 21 Days
3rd + 21 Days
RTS
Exposed Hd % 1 75 26 35 13 17 7 9 2
1055
505 48
185 18
164 16 3
4504
2443 54
842 19
626 14 4
4912
2875 59
855
592 12 5
3675
2269 62
586
406 11
TOTAL
14221
8118 57
2481
1795
Randle RF, Patterson DJ, 2005

38. Comparison of pre-breeding weights by RTS in yearling replacement heifers17
113
673
587
612
Mean, (kg)
302
306
308
337
343
Median, (kg)
307
297
335
341
Mode, (kg)
264
282
318
Range, (kg)
192
166
257
277
Min, (kg)
213
235
186
218
260
Max, (kg)
405
401
443
495
517
1RTS – reproductive tract score. Heifers evaluated were 350 to 410 d of age and of Angus or predominantly Angus breeding.
Randle RF, Patterson DJ, 2005

39. Use of Reproductive Management Technology in Beef Heifers
CHAPA
799 operations
18 top beef states
70% of U.S. beef cow/calf operations
Alabama, Arkansas, California, Colorado, Florida, Georgia, Iowa, Kansas, Kentucky, Mississippi, Missouri, Nebraska, New Mexico, Oklahoma, Tennessee, Texas, Virginia, Wyoming
NAHMS Survey, 1994

40. Selected Management Practices Used on Replacement Beef Heifers
NAHMS Survey, May 1994