1. 2001 ASAS/ADSA 2001 Conference (1) Simultaneous accounting for heterogeneity of (co)variance components in genetic evaluation of type traits N. Gengler 1,2, G.R. Wiggans *,3, J.R. Wright 3, and T. Druet 1,2 1 Gembloux Agricultural University, Belgium 2 National Fund for Scientific Research, Brussels, Belgium 3 Agricultural Research Service, USDA, Beltsville, MD

2. 2001 ASAS/ADSA 2001 Conference (2) USDA Type evaluation  Breeds:  Ayrshire  Brown Swiss  Guernsey  Jersey  Milking Shorthorn  Red and White  15 Linear traits and Final Score  Multi-trait Model  Canonical Transformation  Estimation of missing values

3. 2001 ASAS/ADSA 2001 Conference (3) Heterogeneity of (co)variance  Variances and (co)variances assumed constant across herds and time  Holstein Association accounts for heterogeneity in final score  Variance tends to decrease with increasing herd average final score  Changes in appraisal program over time can be a cause

4. 2001 ASAS/ADSA 2001 Conference (4) Methods of HV estimation  Holstein Association estimates phenotypic variance using combination  observed variance  predicted variance from model including – mean final score – registry status – number of appraisals for herd-classification date  Meuwissen proposed simultaneous estimation of variances and breeding values  expected to improve accuracy of both estimates

5. 2001 ASAS/ADSA 2001 Conference (5) USDA HV adjustment system  Apply Canonical transformation to linear traits  Prepare data for 2 models  score = herd-sire + herd-year-season-parity + parity-time_period-age + parity-time_period-stage  var = mean + parity-group_size + parity- herd_mean_final_score + parity-year-season + herd-year-month

6. 2001 ASAS/ADSA 2001 Conference (6) Variance model  Herd-year-month effect in variance model random  Regression of variances within parity toward population mean (fixed effects)  Method R estimation of variance ratios within each EBV iteration

7. 2001 ASAS/ADSA 2001 Conference (7) Computational requirements February 2001 Jersey Evaluation Run number of rounds time required (hr) no HV4213 with HV4326.5

8. 2001 ASAS/ADSA 2001 Conference (8) Iteration  Time increased due to  iteration for variance model  estimation of variance ratios  Convergence sensitive to  quality of the starting values  size of unknown parent groups  Ways of reducing processing time  parallel processing  using a faster computer  limiting iteration for variances

9. 2001 ASAS/ADSA 2001 Conference (9) Correlations between HV- adjusted official evaluations  February 2001 official evaluations  2497 Jersey AI bulls born 1980+  All correlations.989 or higher

10. 2001 ASAS/ADSA 2001 Conference (10) Change in slope of PTA for Jersey AI bulls Trait slope official slope HV adjdiff pct diff Dairy form 0.27 0.24-0.036-15.4 Rear udder height 0.20 0.17-0.028-16.2 Front teat place 0.09 0.07-0.018-26.4 Strength 0.08 0.07-0.007-10.2 Fore udder attach 0.06 0.05-0.003 -5.7 Teat length 0.02 0.004 22.5 Udder Depth-0.05-0.040.01024.8

11. 2001 ASAS/ADSA 2001 Conference (11) Differences between HV-adjusted and official evaluation  Standard deviations & mean absolute values  increased as reliabilities increased to 80%  decreased slightly for reliabilities of > 90%  Mean differences largest for bulls  born from 1985 through 1994  with lowest mean daughters final scores

12. 2001 ASAS/ADSA 2001 Conference (12) Mendelian sampling  Mendelian sampling  evaluation minus mean of parent evaluations  Jersey cows born from 1984 through 1998  regression of SD on birth year

13. 2001 ASAS/ADSA 2001 Conference (13) Mendelian sampling Trait slope official slope HV adjdiff pct diff Foot angle-0.0050-0.00260.002451 Rump angle-0.0160-0.01220.003876 Rear udder height-0.0050-0.00110.003921 Teat placement-0.0097-0.00550.004257 Stature-0.0199-0.01350.006468

14. 2001 ASAS/ADSA 2001 Conference (14) Interbull trend validation  Trend tests conducted for  Stature  Udder support  Comparison  first parity v. all parities  without recent years v. all data  Trend differences within tolerance

15. 2001 ASAS/ADSA 2001 Conference (15) HV model implementation plans  Jersey - May 2001  Other breeds by Feb 2002

16. 2001 ASAS/ADSA 2001 Conference (16) Conclusions  Simultaneous estimation of BV & Variances possible  Requires substantially more computer time  Improves stability of Mendelian Sampling Variance over time  HV adjusted EBV enable more accurate selection decisions