1. H. Duane Norman Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD 20705-2350 duane.norman@ars.usda.gov NDHIA – 2011 (1) Consequence for U.S. dairy herds of imposing different SCC standards

2. Norman NDHIA – 2011 (2) U.S. milk quality measures l Bulk tank somatic cell count (BT-SCC) w Monitored by USDA w Data from 4 of 10 FMOs w Accounts for nearly 50% of U.S. milk supply l Herd test-day somatic cell count (TD-SCC) w Herds in DHI w Accounts for 94% of U.S. DHI herds

3. Norman NDHIA – 2011 (3) U.S. SCC (all breeds)

4. Norman NDHIA – 2011 (4) BT-SCC limits Country SCC limit (cells/mL) Australia400K Canada500K E.U.400K New Zealand400K Norway400K Switzerland400K U.S.750K CA600K NMPF proposed SCC limits DateCells/mL 1-1-2012600K 1-1-2013500K 1-1-2014400K

5. Norman NDHIA – 2011 (5) U.S. and Canadian SCC U.S. TD-SCC Québec BT-SCC Ontario BT-SCC

6. Norman NDHIA – 2011 (6) U.S. and New Zealand SCC U.S. TD-SCC New Zealand TD-SCC

7. Norman NDHIA – 2011 (7) U.S. and Irish SCC U.S. TD-SCC Irish BT-SCC

8. Norman NDHIA – 2011 (8) 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 400K cells/mL750K cells/mLBT-SCC limit E.U.U.S. Program characteristic

9. Norman NDHIA – 2011 (9) 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

10. Norman NDHIA – 2011 (10) Export concerns l E.U. change in SCC sampling point from bulk truck or plant silo to individual farm 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

11. Norman NDHIA – 2011 (11) SCC noncompliance comparison l DHI herds and FMO herds l Current E.U. and U.S. SCC standards as well as 3 NMPF proposed standards w Percentage of herds w Percentage of milk supply l Examined by month, herd size, and state

12. Norman NDHIA – 2011 (12) DHI Data l SCS converted to SCC for 14,854 DHI herds l Herd requirements w 15–26 tests (Jan. 2009 – Oct. 2010) w ≥10 cows for all test days l Herd TD-SCC used as proxy for BT-SCC w Each cow SCC weighted by her TD milk yield

13. Norman NDHIA – 2011 (13) FMO Data l SCC scores (Jan. 2009 – Oct. 2010) from FMO:  Upper Midwest  Central  Mideast  Southwest ● Included 31,830 producers

14. Norman NDHIA – 2011 (14) DHI herd SCC noncompliance – month

15. Norman NDHIA – 2011 (15) FMO herd SCC noncompliance – month

16. Norman NDHIA – 2011 (16) SCC milk noncompliance in DHI herds -month

17. Norman NDHIA – 2011 (17) SCC milk noncompliance in FMO herds -month

18. Norman NDHIA – 2011 (18) SCC noncompliance in DHI herds – means* Noncompliance SCC standardHerd, %Milk, % 750K, current U.S. 0.90.2 600K, proposed U.S. 2.70.7 500K, proposed U.S. 6.22.0 400K, proposed U.S. 14.15.8 400K, current E.U. 7.83.1 *November 2009 – October 2010

19. Norman NDHIA – 2011 (19) SCC noncompliance in FMO herds – means* Noncompliance SCC standardHerd, %Milk, % 750K, current U.S. 1.0 0.2 600K, proposed U.S. 4.7 1.4 500K, proposed U.S. 11.0 3.8 400K, proposed U.S. 23.310.1 400K, current E.U. 16.1 6.7 *November 2009 – October 2010

20. Norman NDHIA – 2011 (20) SCC DHI herd noncompliance – herd size

21. Norman NDHIA – 2011 (21) SCC FMO herd noncompliance – herd size

22. Norman NDHIA – 2011 (22) SCC herd compliance – state Current U.S., 750K Current E.U., 400K Proposed U.S., 500KProposed U.S., 600KProposed U.S., 400K <5% 5–9.9% 10–24.9% 25–50%

23. Norman NDHIA – 2011 (23) Conclusions l E.U. changes in SCC enforcement led to reconsideration of stricter U.S. standards l If 400K U.S. SCC limits were used, noncompliance would be higher than if current E.U. standard was applied l For U.S. producers to meet stricter SCC standards, sound management and culling for milk quality need to be emphasized. Is DHI the answer?

24. Norman NDHIA – 2011 (24) Acknowledgment Many thanks to Jason Lombard, USDA:Animal and Plant Health Inspection Service:Veterinary Services, Centers for Epidemiology and Animal Health,Fort Collins, CO for providing the results for the FMO herds.