1. 2005 P.M. VanRaden and M.E. Tooker* Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD paul@aipl.arsusda.gov Effect of herd by sire interaction variance on genetic evaluations

2. ADSA 2005 (2) VanRaden and Tooker 2005 Introduction  For almost 40 years, U.S. genetic evaluations have accounted for genotype-environment interaction.  The animal model includes a term for interaction effects of sire and herd.  Multiple daughters of a bull in the same herd have reduced weight.

3. ADSA 2005 (3) VanRaden and Tooker 2005 History of Herd x Sire Effect  Magnitude of H x S variance (c 2 ) estimated to be 14% in 1968 (Plowman and McDaniel JDS 51:306)  More recent research estimated c 2 to be as low as 2% (Dimov et al, 1995 JDS 78:939)  As a result, c 2 lowered to 10% in 1997.

4. ADSA 2005 (4) VanRaden and Tooker 2005 Methods – November 2004  Official November 2004 predicted transmitting abilities (PTA) for Holstein protein yield with c 2 = 10% were compared with PTA computed with reduced c 2 of 5% and 1%.  Repeatability of protein yield was held constant at 0.55 by increasing permanent environmental variance (p 2 ) as c 2 was decreased.

5. ADSA 2005 (5) VanRaden and Tooker 2005 Herd × Sire Variance: Maximum Daughters / Herd Traith2h2 c2c2 p2p2 Maximum Yield3012485.0 30 52017.0 30 71812.1 301015 8.5 Yield35 81210.3 PL8 5 019.2 SCS12 51818.8

6. ADSA 2005 (6) VanRaden and Tooker 2005 Herd x Sire Variance: Daughters / Herd 1% H×S 5% H×S 10% H×S

7. ADSA 2005 (7) VanRaden and Tooker 2005 Mean PTA protein (kg) c2c2 BullsCows 10%18.48.2 5%18.38.1 1%18.28.0

8. ADSA 2005 (8) VanRaden and Tooker 2005 Mean reliability protein (%) c2c2 BullsCows 10%88.649.3 5%89.249.4 1%90.049.4

9. ADSA 2005 (9) VanRaden and Tooker 2005 Correlation with official PTA (c 2 = 10%) c 2 BullsCows 5%0.999 1%0.9930.994

10. ADSA 2005 (10) VanRaden and Tooker 2005 Summary: top 100 active AI bulls  With c 2 reduced from 10 to 5% 98 bulls had no change in PTA protein 2 bulls had PTA changes of 1 kg  With c 2 reduced from 10 to 1% 92 bulls had no change in PTA protein 8 bulls had changes of 1 or 2 kg

11. ADSA 2005 (11) VanRaden and Tooker 2005 Summary: cows born since 1997  Of 2.3 million recent cows, PTA protein changed >4 kg for: 20 cows when c 2 = 5% 1256 cows when c 2 = 1%  Cows changing the most were sired by non-AI bulls with many daughters in one or a few herds.

12. ADSA 2005 (12) VanRaden and Tooker 2005 Implementation – May 2005  H x S variance for yield traits was reduced from 10% to 7% of total.  Repeatability for yield traits was held constant at 55% by increasing permanent environmental variance (p 2 ) from 15% to 18% of total.  For DPR, c 2 was 1%, now is 4%.

13. ADSA 2005 (13) VanRaden and Tooker 2005 May 2005 Herd × Sire Variances: Maximum Daughters / Herd Traith2h2 c2c2 p2p2 Maximum Yield30 71812 Yield (J, B)35 71312 PL8 5 019 SCS12 51819 DPR44525

14. ADSA 2005 (14) VanRaden and Tooker 2005 Herd × Sire Variance: Daughters / Herd 5% H×S 7% H×S 10% H×S

15. ADSA 2005 (15) VanRaden and Tooker 2005 Changes from reducing c 2 from 10% to 7%  99 of the top 100 active AI bulls changed less than 1 kg PTA protein, only 1 bull changed 1 kg.  597 cows changed >4 kg protein out of 2.3 million recent cows. .999 correlation for both bulls and cows.

16. ADSA 2005 (16) VanRaden and Tooker 2005 Foreign experience  Great Britain had herd-by-sire interaction in lactation model but not in test day model research.  Several single herd bulls rose towards the top, so a H x S effect was added back into the new test day model in May.

17. ADSA 2005 (17) VanRaden and Tooker 2005 Conclusions  Reduction of c 2 from 10% to 7% will facilitate AI companies obtaining more daughters per herd in large cooperating herds.  The H x S interaction protects against chance or fraud when sampling is limited to few herds.

18. ADSA 2005 (18) VanRaden and Tooker 2005 Further study ideas  Use of a relationship matrix among herd by sire or herd by animal interactions could be helpful but was not tested in the current studies.  Interactions of sire or animal with region, climate, or country could be useful in the future.