Trends in Noncompliance with Milk Quality Standards for

1
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
2013
TH375
http//aipl.arsusda.gov

• 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).

• 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 (cont.)

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

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

US method (frequency) US method (frequency) US method (frequency) EU method (geometric) EU method (geometric) EU method (geometric)
(1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s 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) US method (frequency) US method (frequency) EU method (geometric)
(1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s 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 lt0.1 1.7 6.8 3.2 1,512
150-199 0.2 1.4 5.3 2.5 718
200-299 lt0.1 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

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

US method (frequency) US method (frequency) US method (frequency) EU method (geometric) EU method (geometric) EU method (geometric)
(1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s of cells/mL) (1000s 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 lt0.1 0.6 2.1
Nov 2011-Oct 2012 0.1 0.9 3.1 lt0.1 0.4 1.4

• US versus EU SCC monitoring

Program characteristic US EU
SCC 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

• CONCLUSIONS
• EU changes in SCC enforcement have led to
  reconsideration of stricter US standards.
• Several US states are strengthening SCC standards
  and it is likely more will do so in the future.
• There has been a continuous steady decline in US
  average SCC the current DHI weighted average is
  200,000 cells/mL.
• Noncompliance at the 400,000 cells/mL level would
  be higher using the US frequency method (9.0 of
  herds, 3.1 of milk) than if the EU geometric
  standard was applied (4.5 of herds, 1.4 of
  milk).
• Most US states show a decrease in noncompliance
  rate over the last several years.
• Large herds are more successful than small herds
  in keeping SCC levels low, but herds of all sizes
  have shown improvements in SCC compliance over
  the last year. (not shown)
• Improvement may be due in part to more stringent
  processor requirements as well as to widespread
  incentive payments.
• With continued improvements in management and
  genetics for milk quality, most dairy producers
  could achieve SCC compliance at a lower level
  than the current US standard.

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

RESULTS

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

• 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

SCC (1000s)

Year
Percentage of herd-tests noncompliant using
current EU SCC standard (400,000 cells/mL) by
state
November 2009-October 2010
November 2010-October 2011
November 2011-October 2012

• OBJECTIVE

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

lt5 5.0 to 9.9
10.0 to 24.9 25.0 to
50.0