Genetic selection for reproduction:

1. Genetic selection for reproduction: Current reproductive status of the national herd; Application of selection indexes for dairy producers

2. 2007 Current reproductive statusof the national herd H.D. Norman Dairy Cattle Reproductive Council Convention (2)

3. Bull fertility • Estimated Relative Conception Rate (ERCR) • 70-day nonreturn rate (NRR) • Phenotypic evaluation • Source: • DRMS (Raleigh, NC), 1986−2005 • USDA (Beltsville, MD), 2006−present • Western Bull Fertility Analysis • 75-d veterinary-confirmed conception rate • Source: AgriTech (Visalia, CA), 2003 −present

4. ERCR distribution (Aug. 2007)

5. Survey of AI organizations • Does your organization rate bulls on fertility from field data? • Where do you obtain the data you use to evaluate them? • How long a time period is included in your evaluation? • What do you publish? • How many nonreturn days are in your calculation? • Is your evaluation derived from first or all services? • Do you eliminate cows sold before a specific number of days after insemination? • Do you eliminate cows in herds that go off test before a specific number of days after insemination? • Is information on services from natural service bulls that follow AI breedings available to you to document failures of those AI breedings?

6. Survey results • All had programs to monitor bull fertility, but few relied completely on in-house information • Most received some information from technician breedings • One purchased breeding records from a dairy records processing center • Another obtained breeding records directly from cooperating herds • Most common fertility measure was NRR • Varied from 59 to 90 days for first breeding • Some organizations used a range of days

7. Survey results (cont.) • Conception rate (CR) used by one because of availability of pregnancy-check records • Time period for data included in a bull’s fertility evaluation varied from 1 year to no limit • Equal number included only first services compared with all services • Data from technician breedings • Not adjusted for cow departures because of culling or when a herd discontinued production testing • No access to data that showed when natural service followed an AI mating

8. New USDA service sire evaluation • Based on conception rate rather than NRR • More accurate • Inseminations from most of the United States • All services (not just first) • Additional model effects included • Available early 2008 • Documentation at ftp://aipl.arsusda.gov/pub/outgoing/BullFert/

9. Cow fertility trends

10. Cow fertility trends

11. Cow fertility trends

12. Cow fertility trends

13. Parity averages (2005 breedings)

14. Parity averages (2005 breedings)

15. Parity averages (2005 breedings)

16. Parity averages (2005 breedings)

17. Holstein NRR (2005 breedings)

18. Holstein CR (2005 breedings)

19. Holstein regional averages (2005 breedings)

20. Holstein regional averages (2005 breedings)

21. Holstein regional averages (2005 breedings)

22. Holstein regional averages (2005 breedings)

23. Pregnancy rate (PR) • Percentage of nonpregnant cows that become pregnant during each 21-day period • Advantages over days open (DO) • Easily defined • Information from nonpregnant cows included more easily • Larger (rather than smaller) values desirable • PR = [21/(DO − voluntary waiting period + 11)]100 • Voluntary waiting period assumed to be 60 days • Factor of +11 adjusts to middle day of 21-day cycle • Examples • Herd with average of 133 DO has PR of 25% • Herd with average of 154 DO has PR of 20%

24. Holstein regional averages (2005 breedings)

25. Herds with synchronized breeding

26. Current breed averages

27. USDA pregnancy rate • Linear approximation • PR = 0.25 (233 − DO) • 1% higher PR = 4 days fewer open

28. Daughter pregnancy rate (DPR) • First USDA genetic evaluations in 2003 • Same across-breed animal model as for yield traits, productive life (PL), and somatic cell score (SCS) • Heritability of 4% • Predicted transmitting abilities (PTAs) reported as percentages • Daughters of bull with PTA DPR of 1 expected to be 1% more likely to become pregnant during estrous cycle than if bull had PTA DPR of 0 • Each increase of 1% in PTA DPR equivalent to decrease of 4 days in PTA DO • PTA DO approximated by −4 × PTA DPR • Example: Bull with PTA DPR of +2.0 would have PTA DO of −8

29. DPR trend (August 2007 base)

30. Bull PTA DPR frequency (Aug. 2007)

31. NM$ CY$ PTI FM$ 2007 Application of selection indexesfor dairy producers H.D. Norman Dairy Cattle Reproductive Council Convention (31)

32. Lifetime merit indexes

33. Genetic merit of high-DPR Holstein bulls

34. Genetic merit of high-DPR Holstein bulls

35. Genetic merit of high-DPR Holstein bulls

36. Genetic merit of high-DPR Holstein bulls

37. Genetic merit of high-DPR Holstein bulls

38. DPR benefits over productive life • Additional calves produced • Decreased units of semen needed per pregnancy • Decreased labor and supplies for heat detection, inseminations, and pregnancy checks • Higher yields because more ideal lactation lengths

39. Lifetime value • Factors in determining economic value • Loss of about $1.50/DO • 2.8 lactations per cow • No breedings for half of cows during final lactation • Correlation of heifer and cow fertility (0.3) • Value of extra calves • Other unmeasured health expenses • Total lifetime merit value of $21/PTA DPR unit

40. Total Performance Index (TPI) • Calculated by Holstein Association USA (Brattleboro, VT) • Emphasis of 19% on early breeding • 10% on PL • 8% on DPR • −1% on dairy form • 95% correlation between USDA lifetime net merit and Holstein TPI

41. 2007 Conclusions H.D. Norman Dairy Cattle Reproductive Council Convention (41)

42. Service sires • Using bulls with higher conception rates returns profit fairly quickly • Premium of $2 could be paid for semen per 1% improvement in fertility • Unit of semen from bull with ERCR of +2 worth $8 more than unit from bull with ERCR of −2 • Little genetic improvement in male fertility expected over time • Use bull fertility as a secondary selection trait after production and economic indexes

43. Selection for cow fertility • Selection for improved fertility possible and recommended • Most benefits delayed for 2 years or more • Select service sires for overall lifetime merit that includes daughter fertility rather than for daughter fertility alone • Producers with herd fertility problems may choose to emphasize DPR extensively, which can be done with little loss in overall net merit

44. Benefits of improved reproduction • Lower semen cost • Improved ability to optimize lactation and lifetime yields • Reduced culling due to delayed or failed conception • More herd replacements

45. Fertility emphasis • Service-sire fertility and DPR important for all management systems, but most important for grazing herds with seasonal calving • Use of a few bulls that average 3.0% for PTA DPR (equivalent to a decrease of 12 DO) could recover much of genetic decline in fertility from use of high-yield bulls for 40 years • General recommendation still is to select for overall merit based on genetic-economic index appropriate for current milk market