1. 2004 P.M. VanRaden, M.E. Tooker*, and J.B. Cole Animal Improvement Programs Laboratory Agricultural Research Service, USDA, Beltsville, MD mtooker@aipl.arsusda.gov Heterosis and breed differences for daughter pregnancy rate and calving ease in crossbred dairy cows

2. ADSA-ASAS JOINT MEETING 2004 (2)Melvin Tooker 2004 Objectives  Document the number and type of crossbred dairy animals in the US.  Estimate heterosis and breed differences for DPR and calving ease of F1 cows.

3. ADSA-ASAS JOINT MEETING 2004 (3)Melvin Tooker 2004 Crossbred Animals  Animals are considered crossbred if available pedigrees include ancestors of more than one breed.  AIPL crossbred table includes over 335,000 animals of which 80,211 are F1s.  Crossbreds are currently updated with every evaluation.

4. ADSA-ASAS JOINT MEETING 2004 (4)Melvin Tooker 2004 Daughter Pregnancy Rate  AIPL database has over 32 million records  Days open restricted from 50 to 250 d  Pregnancy Rate =.25 * (233 - DO)  Calvings since 1990

5. ADSA-ASAS JOINT MEETING 2004 (5)Melvin Tooker 2004 Daughter Pregnancy Rate  First lactation records 13,540 F1 cows from 5397 herds 200,992 purebred contemporaries  Lactations 1 to 5 507,584 records from 6223 herds

6. ADSA-ASAS JOINT MEETING 2004 (6)Melvin Tooker 2004 DPR Model Effects  Herd-year-season of calving  Linear and quadratic effects for age at first calving  Lactation number  Regression on sire PTA  Breed composition  General heterosis

7. ADSA-ASAS JOINT MEETING 2004 (7)Melvin Tooker 2004 Number of F1 and Purebred Cows first lactation Sire Dam Breed BreedAYBSGUHOJEMS AY 1857313268263 BS 311632222625911 GU 4141892286200 HO 6295261584186,902883254 JE 495384623288254 MS 6652229353

8. ADSA-ASAS JOINT MEETING 2004 (8)Melvin Tooker 2004 Number of F1 and Purebred Cows all lactations Sire Dam Breed BreedAYBSGUHOJEMS AY 1990314300294 BS 413314125386913 GU 7231977335260 HO 7126001810193,2471038316 JE 5559103684194385 MS 66726012409

9. ADSA-ASAS JOINT MEETING 2004 (9)Melvin Tooker 2004 Daughter Pregnancy Rate First Lactation All Lactations Breed Average Heterosis2.4 ± 0.6*** 1.8 ± 0.4*** AY0.7 ± 0.8 1.6 ± 0.4+ 0.5 BS0.6 ± 0.7— 0.2 ± 0.4— 0.4 GU1.6 ± 1.1 1.6 ± 0.7**— 1.0 JE4.2 ± 0.4*** 4.6 ± 0.2***+ 4.7 MS4.3 ± 1.7** 4.0 ± 0.9**+ 3.7

10. ADSA-ASAS JOINT MEETING 2004 (10)Melvin Tooker 2004 DPR Conclusions  Estimates are similar to breed differences obtained from national breed averages of first lactation DPR.  JE x HO crossbreds are as fertile as purebred JE.  Heterosis is about 10% of mean DPR.

11. ADSA-ASAS JOINT MEETING 2004 (11)Melvin Tooker 2004 Calving Ease of F1s  First lactation raw difficult birth score records 1861 F1s from 1165 herds 42,564 purebred contemporaries  Lactations 1 to 5 91,172 records from 2022 herds

12. ADSA-ASAS JOINT MEETING 2004 (12)Melvin Tooker 2004 Number of F1 and Purebred Cows calving ease - first lactation Sire Dam Breed BreedAYBSGUHOJEMS AY 16004421 BS 065153533 GU 00752510 HO 27768942,128866 JE 1659232782 MS 1002312

13. ADSA-ASAS JOINT MEETING 2004 (13)Melvin Tooker 2004 Number of F1 and Purebred Cows calving ease - all lactations Sire Dam Breed BreedAYBSGUHOJEMS AY 109007351 BS 0224496893 GU 202325741 HO 14718734885,95224122 JE 392115439382 MS 1105519

14. ADSA-ASAS JOINT MEETING 2004 (14)Melvin Tooker 2004 Calving Ease Model Effects  Herd-year-season of calving  Linear and quadratic effects for age at first calving  Lactation number  Breed composition of dam  Service sire breed

15. ADSA-ASAS JOINT MEETING 2004 (15)Melvin Tooker 2004 F1 Daughter Calving Ease First LactationAll Lactations Heterosis 0.04 ± 0.1— 0.07 ± 0.5 BSxHO— 0.03 ± 0.2— 0.05 ± 0.1 GUxHO— 0.71 ± 0.9— 0.45 ± 0.3 HOxBS— 0.05 ± 0.4— 0.14 ± 0.2 HOxJE— 0.04 ± 0.3— 0.07 ± 0.1 JExHO— 0.11 ± 0.2— 0.14 ± 0.1 JE sire— 0.19 ± 0.2— 0.21 ± 0.1***

16. ADSA-ASAS JOINT MEETING 2004 (16)Melvin Tooker 2004 Calving Ease Conclusions  Jersey service sires had lower calving ease scores than other breeds over all lactations.  Holstein dams had slightly more difficulty than other breeds and breed crosses.  Modeling calving ease is complicated.  Only Holsteins are routinely evaluated.