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Title: SOMATIC CELL COUNTS OF MILK FROM DAIRY HERD IMPROVEMENT HERDS DURING 2001

Author
item MILLER, ROBERT - RETIRED, ARS
item Norman, H

Submitted to: AIPL Research Reports
Publication Type: Government Publication
Publication Acceptance Date: 4/1/2002
Publication Date: 4/1/2002
Citation: N/A

Interpretive Summary:

Technical Abstract: Test-day data from all herds enrolled in Dairy Herd Improvement (DHI) somatic cell testing during 2001 was examined to assess the status of national milk quality. Cows with records failing AIPL editing procedures were excluded. Somatic cell score (SCS) is reported to AIPL and was converted to somatic cell count (SCC) for calculating herd and State averages. The current legal limit for bulk tank SCC is 750,000 cells/ml for Grade A producers; lower future maximums have been proposed. Nationally, average SCC during 2001 was 322,000 cells/ml, which was higher than 316,000 cells/ml for 2000. Corresponding averages for 1995-1999 were 304,000, 308,000, 314,000, 318,000 and 311,000. The percentages of herd test days that exceeded 750,000, 600,000, 500,000, and 400,000 cells/ml during year 2001 were 4.9, 10.6, 18.2, and 31.1, respectively. Thus, 4.9% of test-days from DHI herds were higher than the present legal limit for SCC of bulk tank milk. This may overestimate the percentage of herds that would have exceeded the legal limit for bulk tank SCC on test day because the milk of cows treated for mastitis is excluded from the bulk tank but not excluded from the DHI test. Also, the percentage of herd test days exceeding the legal limit would have been higher than the percentage of herds that were rejected from the market because market exclusion only occurs after repeat violations. Variation among States was large. Average SCC's were lower in the far West and higher in the Southeast. SCC differences between geographically adjacent states were substantial, which suggests that mastitis-control regimens have an impact under similar climatic conditions. These results show an alarming increase in national SCC. Greater efforts to improve milk quality are needed.