Consequence for U S dairy herds of imposing

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

U. S. milk quality measures l 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 Herd test-day somatic cell count (TD-SCC) w Herds in DHI w Accounts for 94% of U. S. DHI herds NMC – 2011 (2) Norman

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

BT-SCC limits SCC limit Country (cells/m. L) Australia 400 K Canada 500 K E. U. 400 K New Zealand 400 K Norway 400 K Switzerland 400 K U. S. 750 K CA 600 K NMC – 2011 (4) NMPF proposed SCC limits Date Cells/m. L 1 -1 -2012 600 K 1 -1 -2013 500 K 1 -1 -2014 400 K Norman

U. S. versus E. U. SCC monitoring Program characteristic U. S. E. U. SCC sample Individual farm BT-SCC limit 750 K cells/m. L 400 K cells/m. L Value used Consecutive monthly BT-SCC Geometric mean of 3 monthly BT-SCC Producer suspension 3 of 5 consecutive samples over limit 2 consecutive 3 -month means over limit NMC – 2011 (5) Norman

Export concerns l l l E. U. change in SCC sampling point from bulk truck or plant silo to individual farm 3 -month mean (E. U. ) used as single reference for period, which allows more time to reduce future SCC Geometric mean (E. U. ) mathematically lower than arithmetic mean (U. S. ) and requires recalculation NMC – 2011 (6) Norman

SCC noncompliance comparison l 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 Examined by month, herd size, and state NMC – 2011 (7) Norman

Data l SCS converted to SCC for 14, 854 DHI herds l Herd requirements l w 15– 26 tests (Jan. 2009 – Oct. 2010) w ≥ 10 cows for all test days Herd TD-SCC used as proxy for BT-SCC w Each cow SCC weighted by her TD milk yield NMC – 2011 (8) Norman

SCC herd noncompliance – month Current U. S. (750 K) Proposed U. S. (600 K) Proposed U. S. (500 K) Proposed U. S. (400 K) Current E. U. (400 K) 18 Herd noncompliance, % 16 14 12 10 8 6 4 2 0 Jun 09 Jul 09 Aug Sep 09 09 Oct 09 Nov Dec 09 09 Jan 10 Feb 10 Mar 10 Apr May Jun 10 10 10 Jul 10 Aug Sep 10 10 Oct 10 Date NMC – 2011 (9) Norman

SCC milk noncompliance – month Current U. S. (750 K) Proposed U. S. (600 K) Proposed U. S. (500 K) Proposed U. S. (400 K) Current E. U. (400 K) Milk noncompliance, % 8 6 4 2 0 Jun 09 Jul 09 Aug Sep 09 09 Oct 09 Nov Dec 09 09 Jan 10 Feb 10 Mar 10 Apr May Jun 10 10 10 Jul 10 Aug Sep 10 10 Oct 10 Date NMC – 2011 (10) Norman

SCC noncompliance – means* SCC standard 750 K, current U. S. Noncompliance Herd, % Milk, % 0. 9 0. 2 600 K, proposed U. S. 500 K, proposed U. S. 400 K, current E. U. 2. 7 6. 2 14. 1 0. 7 2. 0 5. 8 7. 8 3. 1 *November 2009 – October 2010 NMC – 2011 (11) Norman

SCC herd noncompliance – herd size 20 Herd noncompliance, % 18 Current U. S. (750 K) 16 Proposed U. S. (600 K) 14 Proposed U. S. (500 K) 12 Proposed U. S. (400 K) Current E. U. (400 K) 10 8 6 4 2 0 1– 49 50– 99 100– 149 150– 199 200– 299 300– 499 500– 999 1, 000+ Cows in herd NMC – 2011 (12) Norman

SCC herd compliance – state <5% 5– 9. 9% 10– 24. 9% 25– 50% Current U. S. , 750 K Proposed U. S. , 600 K Proposed U. S. , 500 K Proposed U. S. , 400 K Current E. U. , 400 K NMC – 2011 (13) Norman

Conclusions l l l E. U. changes in SCC enforcement led to reconsideration of stricter U. S. standards If 400 K U. S. SCC limits were used, noncompliance would be higher than if current E. U. standard was applied For U. S. producers to meet stricter SCC standards, sound management and culling for milk quality need to be emphasized NMC – 2011 (14) Norman