Trends in Noncompliance with Milk Quality Standards for Dairy Herd Improvement Herds in the United States

H. D. Norman*, J. R. Wright

Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350

INTRODUCTION Most countries have an upper limit for

somatic cell count (SCC) because it is considered an indicator of milk quality.

The current US SCC limit remains at 750,000 cells/mL; however the European Union (EU) standard (400,000 cells/mL) is being imposed on many herds exporting dairy products to Europe.

Several US states already have, or are in the process of lowering their SCC limits below the national standard (CA, ID, MT, NV, OR, WA).

Examine the trend in frequency of herd non-compliance for SCC based on current and alternative standards

OBJECTIVE

DATA & METHODS

DATA:

Approximately 95% of Dairy Herd Improvement (DHI) herds are enrolled in somatic cell score (SCS) testing

Used monthly test day SCS from herds enrolled in DHI programs for three 12-mo periods: November 2009 to October 2010, November 2010 to October 2011, and November 2011 to October 2012

Each cow SCS converted to SCC:

SCC = 2(SCS-3) (100,000)

Individual cow SCC weighted by her test day milk yield to produce test-day SCC for the herd

EDITS:

≥ 10 cows for all test days

15 to 26 tests in each 12-mo period

Noncompliance was calculated for SCC levels of 750,000, 500,000 and 400,000 cells/mL for both US and EU methods

RESULTS (cont.)

RESULTS

RESULTS (cont.)

•US DHI Test Day SCC (All Breeds) 2000-2012

•Percentage of US DHI herd-tests noncompliant by SCC level

US method (frequency)

EU method (geometric)

(1000’s of cells/mL)750 500 400 750 500 400

Nov 2009-Oct 2010

0.9 6.2 14.1 0.3 2.9 7.8

Nov 2010-Oct 2011

0.7 5.1 11.7 0.2 2.5 6.7

Nov 2011-Oct 2012

0.4 3.4 9.0 0.1 1.5 4.5

US method (frequency)

EU method (geometric)

(1000’s of cells/mL)750 500 400 750 500 400

Nov 2009-Oct 2010

0.2 2.0 5.8 0.1 1.0 3.1

Nov 2010-Oct 2011

0.1 1.4 4.1 <0.1 0.6 2.1

Nov 2011-Oct 2012

0.1 0.9 3.1 <0.1 0.4 1.4

•Percentage of milk supplied by US DHI herds noncompliant by SCC level

US method (frequency)

EU method (geometric)

(1000’s of cells/mL)

Herd size 750 500 400 400

Number of

herds

10-49 0.8 5.9 13.2 6.7 4,983

50-99 0.2 3.0 8.9 4.4 4,505

100-149 <0.1 1.7 6.8 3.2 1,512

150-199 0.2 1.4 5.3 2.5 718

200-299 <0.1 1.1 5.0 2.6 657

300-499 0.0 0.8 2.3 1.1 612

500-999 0.1 0.1 1.3 0.3 492

≥1000 0.0 0.1 0.8 0.3 376

All herds 0.4 3.4 9.0 4.5 13,855

<5% 5.0 to 9.9% 10.0 to 24.9% 25.0 to 50.0%

November 2009-October 2010 November 2010-October 2011 November 2011-October 2012

Percentage of herd-tests noncompliant using current EU SCC standard (400,000 cells/mL) by state

• US versus EU SCC monitoring

Program characteristic US EUSCC sample Individual farm Individual farm

Bulk tank (BT)-SCC limit

750,000 cells/mL 400,000 cells/mL

Value used Consecutive monthly BT-SCC

Geometric mean of 3-mo BT-SCC

Producer suspension

3 of 5 consecutive samples over limit

4 consecutive 3-mo means over limit

Geometric mean is mathematically lower than arithmetic mean

The EU 3-mo mean uses a single reference for the period, which allows a herd more time to reduce SCC before becoming noncompliant

•Percentage of herd-tests noncompliant by year and month using current EU SCC standard (400,000 cells/mL)

Year

•Percentage of US DHI herd-tests noncompliant November 2011 to October 2012 by herd size and SCC level

TH375 http://aipl.arsusda.gov

2013