Consequence for U.S. dairy herds of imposing different SCC standards

H. Duane NormanAnimal Improvement Programs LaboratoryAgricultural Research Service, USDA Beltsville, MD 20705-2350duane.norman@ars.usda.gov

NDHIA – 2011 (1)

Consequence for U.S. dairy herds of imposing different SCC standards

NormanNDHIA – 2011 (2)

U.S. milk quality measures Bulk tank somatic cell count (BT-SCC)

Monitored by USDA Data from 4 of 10 FMOs Accounts for nearly 50% of U.S. milk

supply

Herd test-day somatic cell count (TD-SCC) Herds in DHI Accounts for 94% of U.S. DHI herds

NormanNDHIA – 2011 (3)

U.S. SCC (all breeds)

NormanNDHIA – 2011 (4)

BT-SCC limits

Country

SCC limit(cells/mL)

Australia 400KCanada 500KE.U. 400KNew Zealand 400KNorway 400KSwitzerland 400KU.S. 750K

CA 600K

NMPFproposed SCC limits

Date Cells/mL1-1-2012 600K1-1-2013 500K1-1-2014 400K

NormanNDHIA – 2011 (5)

200

225

250

275

300

325

98 00 02 04 06 08Year

SCC

(100

0s)

U.S. and Canadian SCC

U.S. TD-SCC

QuébecBT-SCC

OntarioBT-SCC

NormanNDHIA – 2011 (6)

150

200

250

300

350

400

90 92 94 96 98 00 02 04 06 08Year

SCC

(100

0s)

U.S. and New Zealand SCC

U.S. TD-SCC

New ZealandTD-SCC

NormanNDHIA – 2011 (7)

200225250275300325350

94 96 98 00 02 04 06 08Year

SCC

(100

0s)

U.S. and Irish SCC

U.S. TD-SCC

Irish BT-SCC

NormanNDHIA – 2011 (8)

U.S. versus E.U. SCC monitoring

Individual farmIndividual farmSCC sample

2 consecutive3-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

NormanNDHIA – 2011 (9)

Geometric versus arithmetic means

SCC (cells/ml)Example

1Example

2Month 1 400,000 300,000Month 2 500,000 400,000Month 3 600,000 700,000Arithmetic mean 500,000 467,000Geometric mean 493,000 438,000

NormanNDHIA – 2011 (10)

Export concerns 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

NormanNDHIA – 2011 (11)

SCC noncompliance comparison

DHI herds and FMO herds Current E.U. and U.S. SCC standards as

well as 3 NMPF proposed standards Percentage of herds Percentage of milk supply

Examined by month, herd size, and state

NormanNDHIA – 2011 (12)

DHI Data SCS converted to SCC for 14,854 DHI herds

Herd requirements 15–26 tests (Jan. 2009 – Oct. 2010) ≥10 cows for all test days

Herd TD-SCC used as proxy for BT-SCC Each cow SCC weighted by her TD milk yield

NormanNDHIA – 2011 (13)

FMO Data SCC scores (Jan. 2009 – Oct. 2010) from

FMO:

Upper Midwest Central Mideast Southwest

● Included 31,830 producers

NormanNDHIA – 2011 (14)

DHI herd SCC noncompliance – month

NormanNDHIA – 2011 (15)

FMO herd SCC noncompliance – month

NormanNDHIA – 2011 (16)

SCC milk noncompliance in DHI herds -month

NormanNDHIA – 2011 (17)

SCC milk noncompliance in FMO herds -month

NormanNDHIA – 2011 (18)

SCC noncompliance in DHI herds – means*

NoncomplianceSCC standard Herd, % Milk, %750K, current U.S. 0.9 0.2600K, proposed U.S. 2.7 0.7500K, proposed U.S. 6.2 2.0400K, proposed U.S. 14.1 5.8400K, current E.U. 7.8 3.1*November 2009 – October 2010

NormanNDHIA – 2011 (19)

SCC noncompliance in FMO herds – means*

NoncomplianceSCC standard Herd, % Milk, %750K, current U.S. 1.0 0.2600K, proposed U.S. 4.7 1.4500K, proposed U.S. 11.0 3.8400K, proposed U.S. 23.3 10.1400K, current E.U. 16.1 6.7*November 2009 – October 2010

NormanNDHIA – 2011 (20)

SCC DHI herd noncompliance – herd size

NormanNDHIA – 2011 (21)

SCC FMO herd noncompliance – herd size

NormanNDHIA – 2011 (22)

SCC herd compliance – state

Current U.S., 750K

Current E.U., 400K

Proposed U.S., 500K

Proposed U.S., 600K

Proposed U.S., 400K

<5%5–9.9%10–24.9%25–50%

NormanNDHIA – 2011 (23)

Conclusions E.U. changes in SCC enforcement led to

reconsideration of stricter U.S. standards

If 400K 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. Is DHI the answer?

NormanNDHIA – 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.