1. A National Sire Fertility Index

2. Bull fertility (phenotypic ranking)
Estimated relative conception rate (ERCR)
70-day nonreturn rate (NRR)
Source:
DRMS, Raleigh, NC, 1986−2005
USDA, Beltsville, MD, 2006−present
Western Bull Fertility Analysis
75-d veterinary-confirmed conception rate (CR)
Source: AgriTech, Visalia, CA, 2003 −present

3. Sire conception rate (SCR)
New USDA service-sire phenotypic fertility evaluation
Based on CR rather than NRR
More accurate
Inseminations from most of the United States
Services 1–7 (not just first)
Additional model effects included
Implemented August 2008

4. Data included
Only AI inseminations with pregnancy status confirmation (success or failure)
Inseminations 1–7 for cows in lactations 1–5
Lactation length at breeding limited to 30–365 DIM
Cow age of 2–15 yr
Standardized milk yield
>10,000 lb for Holsteins
>8,000 lb for Brown Swiss
>6,000 lb for all other breeds

5. Data included (cont.) Most recent 4 yr of breeding records
Inseminations ≥70 d before data submission deadline
6 traditional U.S. dairy breeds
Ayrshire
Brown Swiss
Guernsey
Holstein
Jersey
Milking Shorthorn

6. Data excluded Embryo-transfer donors Sexed semen Heifers
Consecutive services within 10 d of each other
Only information from later service kept
Earlier service not considered when assigning subsequent service numbers for same lactation

7. Data excluded (cont.)
Herd with ≥50% of milking cows without recorded breeding
Herd CR <10% or >90%
Service sire <0.8 yr old

8. Data sources (August 2008) 3 dairy records processing centers
AgriTech Analytics
AgSource Cooperative Service
DRMS
>99% of data
46 States and Puerto Rico

9. Development of SCR 4-year research effort – primarily by
Dr. Melvin Kuhn
Bull variables (expanded service-sire effect)
Cow (nuisance) variables

10. Bull variables Inbreeding Service sire Embryo Bull age
AI organization combined with mating year
Bull

11. Cow variables
Combined herd, mating year, cow parity, and cow registry status
Combined mating month, year, and State
Cow parity
Service number
Short interval between matings
Cow age
Cow standardized milk yield
Cow’s permanent environment
Cow’s genetics

12. SCR model
Categorical effects
Individual parities for lactations 1–5
State-year-month of insemination group
6 standardized milk yield groups
Service number for inseminations 1–7
Cow age
Herd-year-season-parity-registry status class
Covariate (linear regression) effects
Service-sire inbreeding coefficient
Mating inbreeding coefficients
Random effects
Service-sire age group
AI organization-insemination year group
Individual service sire
Cow’s genetic ability to conceive
Cow’s permanent environmental effect
Residual
“The most complex model that I know of to evaluate animal performance”
— Bennet Cassell,
VPISU, 2008

13. Variances Service-sire age 0.00014
AI organization-insemination year
Service sire
Cow
Cow’s permanent environment
Residual

14. SCR accuracy Reliability (R) = n/(n + 260) n = number of inseminations
Constant 260 derived by including all random effects in expanded service sire term
Confidence interval (CI) =
= true standard deviation
1.282 = standard normal variate from normal
distribution for an 80% CI

15. Relationship of R and 80% CI
Inseminations
R (%)
80% CI
200 43
± 2.2
300 54
± 2.0
500 66
± 1.7
1,000 79
± 1.3
2,000 88
± 1.0
5,000 95
± 0.7
10,000 97
± 0.5
15,000 98
± 0.4
20,000 99
± 0.3

16. Proposed CI table Bull name SCR (%) R 80% CI A 1.6 99 1.3 to 1.9 B 0.898
0.4 to 1.2 C
−0.4 90
−1.3 to 0.5 D
1.1 82
−0.2 to 2.4 E
−3.8 77
−5.2 to −2.4 F
2.3 59
0.4 to 4.2

17. SCR release
Released 3 times a year in conjunction with USDA national genetic evaluations
January
April
August
Only AI bulls ≤15 yr old
Active AI
Progeny test

18. SCR release (cont.) Overall matings Holstein ≥300 in ≥10 herds
Ayrshire, Brown Swiss, ≥200 in ≥5 herds
Guernsey, Jersey
Milking Shorthorn ≥100 in ≥5 herds
Matings during current 12 mo
Holsteins, Jersey ≥100
Ayrshires, Brown Swiss, ≥30
Guernsey
Milking Shorthorn ≥10

19. Interpretation of SCR Phenotypic predictor of bull fertility
Expressed as relative CR
Reported as a percentage
Average bull has SCR of 0.0%
Standard deviation for August 2008 SCR was 2.4%

20. Examples
Bull with SCR of 3.0% expected to have 3% higher CR than average bull and 6% higher CR than bull with SCR of −3.0%
Bull with SCR of 2.0% expected to have CR of 32% in herd that normally averages 30% and historically has used bulls with average SCR

21. Impact of individual effects
Individual effects sequentially removed from full model to test alternative models
Service-sire inbreeding
Mating inbreeding
Service-sire age
AI organization-insemination year
Each effect added back to the model and another effect removed

22. Correlations of alternatives with full model
Alternative model
AI organization
All A B C D E F
No mating
inbreeding
1.00
No service-sire
No AI organization-
insemination year
0.98
No service-sire age
0.95
0.94
0.93
0.92
Interpolated age
0.99

23. Service-sire age effect
Greatest impact on SCR prediction across and within AI organization
Interpolated age expected to provide most consistent evaluations across time
Not intended for comparison of rankings at a common age
Provide more accurate representation of phenotypic value of CR for a bull’s semen at this point in his life

24. Maximum absolute change
Individual bull
Comparison with January 2008 full-model evaluation
Change
Alternative models (percentage units)
No AI organization-insemination year 2.2
No service sire-age 1.9
Interpolated age 0.9
No service-sire inbreeding 0.8
No mating inbreeding 0.2

25. Prediction effectiveness
July 2006 Holstein SCR from alternative models
Average CR for later (July 2006 – January 2008) inseminations
Deviation of outcome for each later insemination from average for all inseminations in same herd-year-season
Herd fertility differences removed
≥300 inseminations for each bull SCR and either ≥100 or ≥300 inseminations for later CR

26. Bull correlations of SCR with later CR
Model
Bulls with 100 inseminations
Bulls with 300 inseminations
Full model
0.6213
0.6526
No mating
inbreeding
0.6222
0.6536
No service-sire
0.6189
0.6497
No AI organization-
insemination year
0.6179
0.6488
No service-sire age
0.6089
0.6326
Interpolated age
0.6238
0.6549

27. Optimal AI organization-insemination year
AI industry concern
NAAB code used to assign bulls to AI organization-insemination years
Not as effective in predicting future CR as assigning all bulls to most recent AI organization-year
Assigning bulls to AI organization-year just prior to most recent also of considerable value

28. Optimal AI organization-year (cont.)
Additional studies applied multiple-regression methods
Prediction of future CR most improved by including 2 most recent AI organization-years
60% weighting for most recent year
40% weighting for previous year

29. Herd fertility
Relationship between bull SCR and fertility of herds for which bull was service sire
Herd-years stratified into 3 equally sized groups by CR
≤27.3% Low fertility
27.4 to 33.9% Medium fertility
≥34.0% High fertility
Bulls stratified into 3 equally sized groups by SCR
≤−0.9% Low fertility
−0.8 to 1.0% Medium fertility
≥1.1% High fertility

30. Herd CR (August 2008) Service-sire fertility Herd fertility Low Medium
High
20.3
27.4
35.3
22.6
30.0
38.7
24.8
32.4
41.4
Difference
4.5
5.0
6.1

31. Conclusions New SCR evaluation Based on confirmed pregnancies
Measures phenotypic service-sire fertility
Expressed as a relative CR (average bull has SCR of 0.0%)
Standard deviation of 2.4% in August 2008

32. Conclusions (cont.)
First official SCR evaluations released in August 2008 for active-AI and progeny- test bulls
Data from >80% of DHI herds that collect breeding information
Most States and Puerto Rico represented for 6 dairy breeds

33. Conclusions (cont.)
SCR more accurate than ERCR because of data from 3 times more inseminations
More DHI herds (Western herds added)
Extra services (2–7)

34. Female fertility evaluations
Genetic evaluations to be implemented in 2009
Heifer conception rate (HCR)
Percentage of inseminated heifers that become pregnant at each service
Cow conception rate (CCR)
Percentage of inseminated cows that become pregnant at each service
Similar to reporting for daughter pregnancy rate (DPR)
Will be reported to Interbull

35. Acknowledgments
Reproductive records supplied by AgriTech Analytics, AgSource Cooperative Service, and DRMS
Willingness of U.S. dairy producers to record their management data essential for continuation of effective fertility evaluation
Suggestions provided by the National Association of Animal Breeders’ Fertility Committee beneficial in development of SCR