Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/23/2013
Publication Date: 7/8/2013
Citation: Norman, H.D., Wright, J.R. 2013. Trends in noncompliance with milk quality standards for dairy herd improvement herds in the United States. Journal of Dairy Science. 96(E-Suppl. 1):603 (abstr. TH375). Interpretive Summary:
Technical Abstract: Frequency of herd noncompliance for somatic cell count (SCC) based on current US and European Union (EU) standards as well as for standards proposed by the National Milk Producers Federation (NMPF) was examined for US Dairy Herd Improvement (DHI) herds. For current US standards, regulatory action is taken if bulk-tank SCC (BTSCC) for 3 of 5 consecutive monthly shipments is >750,000 cells/mL. For EU standards, a herd is SCC noncompliant after 4 consecutive rolling 3-test geometric means of >400,000 cells/mL. For proposed NMPF standards, a herd would be SCC noncompliant if 3 of 5 consecutive BTSCC were >600,000 cells/mL (January 2014) or >400,000 cells/mL (January 2015). The SCC for individual cows are derived from somatic cell scores, where SCC = 2(somatic cell score – 3)(100,000). As a BTSCC proxy for determining which herds and milk were SCC noncompliant, herd test-day SCC (HTSCC) were derived by weighting each cow’s SCC by her test-day milk yield. Based on HTSCC, noncompliance rates were examined for various milk quality standards, with a focus on trends during the last 2 yr, as the EU standards have been imposed upon many US dairies producing for export. Data were from about 13,000 DHI herds monthly and represented about 50% of US milk produced. Herds included had DHI tests with >=10 cows from April 2009 through October 2010 or from April 2011 through October 2012. Mean monthly herd noncompliance based on current US standards dropped from 0.9 to 0.4% over the last 2 yr. For NMPF proposed standards, herd noncompliance would have dropped from 2.7 to 1.4% for a limit of 600,000 cells/mL or from 14.1 to 9.0% for 400,000 cells/mL. For the EU standard, herd noncompliance would have been reduced from 7.8 to 5.0%. The percentage of milk affected by noncompliance is considerably less than the percentage of herds; only 0.1 and 1.4% of US milk failed current US and EU SCC standards, respectively. Trends indicate a continued improvement in US SCC compliance levels but in order to satisfy stricter milk standards, US producers will need to continue to emphasize sound milking practices more and cull on SCC more intensively.