1. H. Duane Norman Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD 20705-2350, USA duane.norman@ars.usda.gov EAAP – 2010 (1) Recent trends in mastitis and fertility indicators in the United States and reasons for change Session 18 Abstr. 7375

2. Norman EAAP – 2010 (2) Mastitis indicators Source: Purdue Dairy Clipart Source: Dairy Herd Management

3. Norman EAAP – 2010 (3) International BT-SCC limits Country/groupLimit (cells/ml) Australia400,000 Canada500,000 European Union400,000 New Zealand400,000 Norway400,000 Switzerland400,000 United States750,000 California600,000

4. Norman EAAP – 2010 (4) U.S. milk quality measures l Bulk tank somatic cell count (BT-SCC) w Monitored by U.S. Department of Agriculture w Data from 4 of 10 Federal Milk Marketing Orders (FMO) w Accounts for nearly 50% of US milk supply l Herd test-day somatic cell count (TD-SCC) w Herds in Dairy Herd Improvement (DHI) somatic cell testing w Accounts for 97% of US DHI herds

5. Norman EAAP – 2010 (5) U.S. SCC (all breeds)

6. Norman EAAP – 2010 (6) U.S. herd size and SCC 100 125 150 175 200 225 250 980002040608 Year Cows/herd (no.) 200 225 250 275 300 325 TD-SCC (1000s)

7. Norman EAAP – 2010 (7) U.S. herd milk yield and SCC 9,000 9,250 9,500 9,750 10,000 10,250 980002040608 Year Milk (kg) 200 225 250 275 300 325 TD-SCC (1000s)

8. Norman EAAP – 2010 (8) l SCS used by U.S. DHI as a mastitis indicator w Simplicity w Desirable statistical properties (nearly normal distribution) l Conversion equations w SCS = log 2 (SCC/100,000) + 3 w SCC = 2 (SCS − 3) (100,000) Somatic cell score (SCS) SCS SCC (cells/ml) 012,500 125,000 250,000 3100,000 4200,000 5400,000 6800,000 71,600,000 83,200,000 96,400,000

9. Norman EAAP – 2010 (9) SCS and change in herd size

10. Norman EAAP – 2010 (10) U.S. and Canadian SCC U.S. TD-SCC Québec BT-SCC Ontario BT-SCC

11. Norman EAAP – 2010 (11) U.S. and New Zealand SCC U.S. TD-SCC New Zealand TD-SCC

12. Norman EAAP – 2010 (12) U.S. and Irish SCC U.S. TD-SCC Irish BT-SCC

13. Norman EAAP – 2010 (13) German SCC “No increase or decrease in SCC for German Holsteins across time” – Reinhard Reents (personal communication, 2010)

14. Norman EAAP – 2010 (14) U.S. versus E.U. SCC monitoring Individual farm SCC sample 2 consecutive 3-month means over limit 3 of 5 consecutive samples over limit Producer suspension Geometric mean of 3 monthly BT-SCC Consecutive monthly BT-SCC Value used 400,000 cells/ml750,000 cells/mlBT-SCC limit E.U.U.S. Program characteristic

15. Norman EAAP – 2010 (15) Export concerns l E.U. change in SCC sampling point from bulk truck or plant silo to individual farm (October 1, 2010, enforcement) l 3-month mean (E.U.) used as single reference for period, which allows more time to reduce future SCC l Geometric mean (E.U.) mathematically lower than arithmetic mean (U.S.) and requires recalculation

16. Norman EAAP – 2010 (16) Geometric versus arithmetic means SCC (cells/ml) Example 1Example 2 Month 1400,000300,000 Month 2500,000400,000 Month 3600,000700,000 Arithmetic mean500,000467,000 Geometric mean493,000438,000

17. Norman EAAP – 2010 (17) Fertility indicators Source: English Guernsey Cattle SocietySource: BBC (Louise Cassidy)

18. Norman EAAP – 2010 (18) Holstein Jersey U.S. days to 1st breeding

19. Norman EAAP – 2010 (19) U.S. Holstein days to 1st breeding – – – 1st parity –––– All parities

20. Norman EAAP – 2010 (20) U.S. Jersey days to 1st breeding – – – 1st parity –––– All parities

21. Norman EAAP – 2010 (21) Holstein – – – 1st breeding –––– All breedings Jersey – – – 1st breeding –––– All breedings U.S. non-return rates (70 days) 40 45 50 55 60 980002040608 Breeding year Non-return rate (%)

22. Norman EAAP – 2010 (22) Holstein – – – 1st breeding –––– All breedings Jersey – – – 1st breeding –––– All breedings U.S. conception rates 20 25 30 35 40 45 980002040608 Breeding year Conception rate (%)

23. Norman EAAP – 2010 (23) U.S. heifer and cow conception rates l Genetic evaluations implemented w Bulls – January 2009 w Cows – August 2010 l Single-trait BLUP evaluation within breed l Data w Calvings during 2003 or later w Parities 1–5 w Services 1–7 w Age: Heifers1 to <2.2 years Cows≥2 years

24. Norman EAAP – 2010 (24) U.S. Holstein conception rates 30 40 50 60 70 010203040506 Birth year Conception rate (%) -6.0 -3.0 0.0 3.0 6.0 Breeding value (%) –––– Heifer CR – – – Heifer BV –––– Cow CR – – – Cow BV

25. Norman EAAP – 2010 (25) Holstein Jersey U.S. numbers of services

26. Norman EAAP – 2010 (26) U.S. Holstein numbers of services – – – 1st parity –––– All parities

27. Norman EAAP – 2010 (27) U.S. Jersey numbers of services – – – 1st parity –––– All parities

28. Norman EAAP – 2010 (28) Pregnancy rate l Allows herd managers to measure how quickly their cows become pregnant again after having a calf l Defined as percentage of nonpregnant cows that become pregnant during each 21-day period

29. Norman EAAP – 2010 (29) U.S. pregnancy rates Jersey –––– PR – – – BV Holstein –––– PR – – – BV 20 22 24 26 28 30 909294969800020406 Birth year Pregnancy rate (%) -2.5 -0.5 1.5 3.5 5.5 7.5 Breeding value (%)

30. Norman EAAP – 2010 (30) Holstein Jersey U.S. calving intervals

31. Norman EAAP – 2010 (31) U.S. Holstein calving intervals – – – 1st parity –––– All parities

32. Norman EAAP – 2010 (32) U.S. Jersey calving intervals – – – 1st parity –––– All parities

33. Norman EAAP – 2010 (33) Herd synchronization status l Identified through χ 2 analysis with herd size considered w Deviation of observed frequency of 1st inseminations by day of the week from expected equal frequency w Maximum percentage of cows inseminated on a particular day of the week l Status categories w Not synchronized w Possibly synchronized w Probably synchronized w Synchronized

34. Norman EAAP – 2010 (34) Year Not synchronized Possibly synchronized Probably synchronizedSynchronized 199865163402536 1999632042339211 2000636745964717 2001654557780656 20026460570100158 20037111633126990 200468697411558147 200564937401801242 200659307011935340 200758407012199443 200853736362232549 U.S. herd synchronization (no.)

35. Norman EAAP – 2010 (35) Year Not synchronized Possibly synchronized Probably synchronizedSynchronized 19989254<1 19998866<1 20008569<1 2001827101 2002807121 2003787141 2004748172 2005708193 2006678224 2007648245 2008617256 U.S. herd synchronization (%)

36. Norman EAAP – 2010 (36) U.S. herd synchronization (%)

37. Norman EAAP – 2010 (37) Year Not synchronized Possibly synchronized Probably synchronizedSynchronized 19989154<1 19998577<1 200080812<1 2001759141 20027010191 2003659242 20045810284 2005529335 2006479368 2007459378 20084293911 U.S. cows by herd synchronization (%)

38. Norman EAAP – 2010 (38) Synchroni- zation status Days to 1st breeding (days) Concep- tion rate (%) Services (no.) CaIvin g interval (days) Not synchronized 88312.4419 Possibly synchronized 79292.6413 Probably synchronized 75292.6412 Synchronize d 77302.6414 U.S. Holstein synchronization and reproduction* *2008 breedings

39. Norman EAAP – 2010 (39) U.S. sexed-semen use Population Breeding year Breedings (no.) Percentage of total breedings Heifers20065,5501.4 200741,3409.5 200881,81217.8 Cows20061,9620.1 20077,7790.2 200816,1690.4

40. Norman EAAP – 2010 (40) U.S. sexed-semen conception rates Conception rate (%) Population Breeding year Conventional semen Sexed semen Heifers20065532 20075642 20085539 Cows200630 20073026 20083124

41. Norman EAAP – 2010 (41) Conclusions l Large decline in U.S. SCC during last decade while herd size and milk yield increased l In spite of less stringent legal standards, U.S. SCC comparable with SCC in other countries (probably because of incentives) l U.S. days to 1st breeding declined partly because of adoption of ovulation synchronization and timed AI

42. Norman EAAP – 2010 (42) Conclusions (continued) l Units of semen per conception increased somewhat in the U.S. l U.S. pregnancy rates decreased and calving intervals increased for decades but are improving l Use of synchronized breeding has grown in the U.S.

43. Norman EAAP – 2010 (43) Conclusions (continued) l Use of sexed semen for heifers has grown in the U.S. l Conception rate with sexed semen 20–30% less than with conventional semen in the U.S.

44. Norman EAAP – 2010 (44) Thank you! Animal Improvement Programs Laboratory staff – 2010