Department of Agricultural and Applied Economics, University of Wisconsin-Madison 53706-1503, USA.
J Dairy Sci. 2012 Nov;95(11):6421-35. doi: 10.3168/jds.2012-5522. Epub 2012 Sep 12.
Consumer and processor demand for high-quality milk has placed increasing pressure on US milk producers to achieve higher product standards. International standards for somatic cell count (SCC) are becoming more stringent, but in May 2011, the United States National Conference on Interstate Milk Shipments chose to retain the 750,000 cells/mL standard. Using ordinary least squares and quantile regressions on US Department of Agriculture Agricultural Resource Management Survey Dairy Costs and Returns Report data for 2005, we model producer and farm-level characteristics associated with SCC. Quantile regression analysis allows for a more parsed inquiry into statistical associations. Dairy Costs and Returns Report data provide cross-sectional information on the physical structure, input expenses, demographics, and outputs for farms in selected states. Location outside the Southeast, lower herd age, full-time farming status, use of biosecurity guidelines, good milking facilities and operations management, and application of related quality tests are all associated with lower SCC levels. Size of operation had little effect on SCC levels after controlling for other factors. Many of the operations that did not attain a more demanding SCC standard of 400,000 cells/mL had older operators, operators who expressed intention to exit within 10 yr, smaller size, and location in the Southeast when compared with those meeting the tighter standard. The results suggest that the stricter scheme favors larger farms that are more committed to production and are less likely to be sole or family proprietorships.
消费者和加工商对高质量牛奶的需求,给美国牛奶生产商带来了越来越大的压力,要求他们达到更高的产品标准。体细胞计数 (SCC) 的国际标准越来越严格,但在 2011 年 5 月,美国州际牛奶运输会议选择保留 75 万个细胞/毫升的标准。我们使用普通最小二乘法和分位数回归对 2005 年美国农业部农业资源管理调查乳制品成本和收益报告的数据进行了分析,以建立与 SCC 相关的生产者和农场特征模型。分位数回归分析可以更深入地研究统计关联。乳制品成本和收益报告的数据提供了有关选定州的农场的物理结构、投入费用、人口统计和产出的横截面信息。位于东南部以外、牛群年龄较低、全职务农、使用生物安全准则、良好的挤奶设施和运营管理,以及应用相关质量测试,都与较低的 SCC 水平有关。在控制了其他因素后,运营规模对 SCC 水平的影响不大。与达到更严格的 40 万个细胞/毫升 SCC 标准的操作相比,许多未达到该标准的操作的经营者年龄较大,计划在 10 年内退出的经营者比例较高,规模较小,而且位于东南部。结果表明,更严格的方案有利于规模较大、更致力于生产、不太可能是独资或家族企业的农场。