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Update on AIPL Research, 2008–09

Update on AIPL Research, 2008–09. I 9 DHIA!. Recent research projects. Reported abortions frequency in DHI herds Johne’s scores from DHI herds Sexed-semen use and its impact on reproductive traits. Abortions reported (R. H. Miller).

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Update on AIPL Research, 2008–09

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  1. Update onAIPL Research,2008–09 I 9 DHIA!

  2. Recent research projects • Reported abortions frequency in DHI herds • Johne’s scores from DHI herds • Sexed-semen use and its impact on reproductive traits

  3. Abortions reported (R. H. Miller) • 2.9 million lactations reports from pregnant cows (1995–2005) • Determination of abortion based on DHI termination code 8 • Reported abortion frequency examined among parities, seasons, stages of pregnancy, breeds, milk yields, regions, and herd sizes • Reported abortion frequency of 1.5%

  4. Abortions & season • Reported abortions most frequent from February through August • Fewest abortions reported during November and December

  5. Abortions & parity • Reported abortion frequency decreased as parity increased

  6. Abortions & pregnancy stage • Abortions most frequent early in pregnancy

  7. Abortions & breed & milk yield • Reported abortion frequency was lowest for Jerseys, intermediate for other breeds (+0.2 percentage units), and highest for Holsteins (+0.3 percentage units)

  8. Abortions & breed & milk yield • High milk yield associated with increased reported abortions

  9. Abortions & herd size • Larger herd size associated with increased reported abortions

  10. Abortions & region • Abortions reported most in the Southwest 0.8 0.4 0.3 0.4 0.4 1.9 0.0 Abortion frequency (%) difference from cows in the Southeast

  11. Johne’s studies • Characteristics of milk ELISA scores in Holsteins and factors affecting scores • Antel BioSystems (T. M. Byrem, H. D. Norman, & J. R. Wright) • Estimation of genetic parameters and transmitting ability for milk ELISA scores • University of Minnesota (S. A. Attalla, A. J. Seykora, J. B. Cole, & B. J. Heins)

  12. Characteristics of ELISA tests • Cow distribution by parity • Score distribution by days from calving to test • Birth and test seasons (four 3-mo seasons starting in January) uniformly distributed • Score distribution by year

  13. Milk ELISA score characteristics • Average score of 0.04 (±0.18) for 196,412 tests from 696 herds in 16 States from 2002 through 2008 • 6.1 and 3.2% positives based on cutoffs of 0.10 and 0.40 • Same average and SD for 42,778 scores from 25 more comprehensively tested herds in Michigan and Wisconsin • 5.6 and 3.0% positives

  14. ELISA characteristics, (+ at 0.1) • Cows with multiple tests within parity (12%) • 95% negative for last test if 1st test negative • 52% positive for last test if 1st test positive • Cows with multiple tests across parities (36%) • 91% negative for last test if 1st test negative • 47% positive for last test if 1st test positive

  15. ELISA characteristics (various +) • Milk yield differences (within herd and year) between cows with negative and positive scores • Similar yield differences until score cutoff is >0.05 • Percentage of infected cows in “positive” group • Lower productivity for infected cows revealed • Untested cows had lower average yield than tested cows (even cows with positive tests)

  16. Milk ELISA characteristics (cont.) • Unusually high percentage (44%) of untested cows removed from herd by end of current lactation • Tested cows removed from herd • 15% of positive cows • 12% of negative cows • Further analysis needed to optimize usefulness of DHI records in evaluation of milk testing for Johne's

  17. Factors affecting scores • Scores generally increased with year, parity, and test stage • Birth and test seasons non-significant • Low heritability (1%) • Moderate repeatability (21%) • Results will be reexamined as more data available

  18. Genetic parameters & evaluation • 22,694 records from Minnesota Holstein herds with at least 1 cow positive for Johne’s • Milk ELISA scores transformed using natural logarithm • Heritability, repeatability, and breeding values estimated with linear animal model • Heritability of 0.06 • Repeatability of 0.34

  19. Correlations with other traits • 108 Holstein AI sires with ≥30 daughters in study • PTA correlation with breeding value for ELISA score • Milk (0.01) • Fat (–0.05) • Protein (0.00) • Selection based on SCS, productive life, DPR, and net merit could improve resistance to Johne’s • SCS (0.19) • Productive life (–0.26) • DPR (–0.21) • Net merit (–0.26)

  20. Sexed-semen studies (Norman & Hutchison) • Characterization and usage based on U.S. field data • Effect on reproductive traits • Conception rate • Calf sex • Dystocia • Stillbirth

  21. Sexed-semen characterization • Determination of sexed-semen breedings • NAAB marketing code 500 (514 excluded) • AIPL format-5 records • Of 717 active-AI Holstein bulls born since Jan 1, 1994, sexed semen was marketed before April 2008 for 211 (29%) of them

  22. Sexed-semen characteristics (cont.) • Holstein bulls with sexed semen available from Jan. 2006 through April 2008 slightly superior genetically • Yield traits • SCS • Productive life • DPR • Holstein bulls with sexed-semen by net merit decile • Calving ease • Stillbirth • Net merit

  23. Sexed-semen use • Holstein breedings with sexed semen by year • 54% of Holstein sexed-semen breedings to heifers; 46% to cows (through April 2008) • Heifer sexed-semen breedings (through Oct. 2008) • 80% for 1st breeding • 16% for 2nd breeding • 3% for 3rd breeding

  24. Sexed-semen use (cont.) • Cow sexed-semen breedings (through Oct. 2008) • 43% during 1st lactation • 51% for 1st breeding • 23% for 2nd breeding • 12% for 3rd breeding • 28% during 2nd lactation • 47% for 1st breeding • 25% for 2nd breeding • 13% for 3rd breeding

  25. Sexed-semen use (cont.) • Regional herd use (%) of sexed semen in heifers • Greater in Northwest and Southwest • Lowest in Northeast, Midwest, and Mountain-Prairie states • Varied by region • Similar regardless of herd size

  26. Sexed semen & reproductive traits • Conception rate (Jan. 2006 through Oct. 2008 data) • Overall • Conventional: 57%, heifers; 30%, cows • Sexed semen: 44%, heifers; 26%, cows • Sexed-semen breedings • 1st breeding: 45%, heifers; 29%, 1st-lact. cows • 2nd breeding: 39%, heifers; 27%, 1st-lact. cows • 3rd breeding: 35%, heifers; 25%, 1st-lact. cows • 26% (average), first 3 breedings, 2nd-lact. cows

  27. Sexed semen & reproductive traits (cont.) • Correlation between sire conception rates from sexed and conventional semen • >300 breedings: 0.19, heifers; 0.49, cows • >800 breedings: 0.32, heifers; 0.78, cows • Calf sex and twinning incidences (%)

  28. Sexed semen & reproductive traits (cont.) • Dystocia incidence (%) *Nonsignificant

  29. Sexed semen & reproductive traits (cont.) • Stillbirth incidence (%) *Nonsignificant

  30. Update onAIPL Research,2008–09 That’s all

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