BACKGROUND The dairy industry in Ireland is expanding rapidly, with a focus on the production of high quality milk. Somatic cell counts (SCC) are an important indicator both of udder health and milk quality. Milk sold by Irish farmers for manufacture must comply with EU regulations. Irish SCC data is also subject to a monthly seasonal adjustment, for four months from November to February, on account of the seasonality of milk production in Ireland. In a recent study, however, there was no evidence of a dilution effect on SCC with increasing milk yield in Irish dairy cattle. The aim of this paper is to estimate the impact of removal of the seasonality formula on the eligibility of Irish herds to supply raw milk for processing of dairy products. METHODS Bulk tank SCC data from 2013 were collected from 14 cooperatives in Ireland. The geometric mean of SCC test results was calculated for each calendar month. We then calculated the number of herds and volume of milk supplied falling in three SCC categories (<200,000, 200,000-400,000, >400,000 cells/mL) in Ireland during 2013 based on their geometric mean SCC every month. Each herd was assigned an 'eligibility to supply' status (always compliant, under warning (first warning, second warning, third warning) and liable for suspension) each month based on their 3-month rolling geometric mean, using methods as outlined in EU and Irish legislation. Two methods were used to calculate the 3-month rolling geometric mean. We then determined the number of herds and volume of milk supplied by 'eligibility to supply' status in Ireland during 2013. All calculations were conducted with and without the seasonality adjustment. RESULTS The analyses were performed on 2,124,864 records, including 1,571,363 SCC test results from 16,740 herds. With the seasonality adjustment in place, 860 (5.1%) or 854 (5.1%) of herds should have been liable for suspension during 2013 if calculation method 1 or 2, respectively, had been used. If the seasonality adjustment were removed, it is estimated that the number of herds liable for suspension would increase from 860 to 974 (13.2% increase) using calculation method 1, or from 854 to 964 (12.9% increase) using calculation method 2. CONCLUSIONS The modelled impact of such removal would be relatively minor, based on available data, regardless of the method used to calculate the 3-month rolling geometric mean. The focus of the current study was quite narrow, effectively from July to December 2013. Therefore, the results are an underestimate of the total number of herds liable for suspension during 2013. They may also underestimate the true percentage change in herds liable for suspension, with the removal of the seasonality formula. A national herd identifier was lacking from a sizeable percentage of the 2013 bulk tank SCC data, but will be needed if these data are to be meaningfully used for this or other purposes.

中文翻译：

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取消季节性公式对爱尔兰牛群有资格供应用于加工乳制品的原奶的影响。

背景技术爱尔兰的乳业正在迅速发展，其重点是生产高质量的牛奶。体细胞计数（SCC）是乳房健康和牛奶质量的重要指标。爱尔兰农民出售的用于制造的牛奶必须符合欧盟法规。由于爱尔兰牛奶生产的季节性，爱尔兰的SCC数据还将在11月至2月的四个月内每月进行季节性调整。但是，在最近的一项研究中，没有证据表明爱尔兰奶牛会随着牛奶产量的增加而对SCC产生稀释作用。本文的目的是评估取消季节性公式对爱尔兰牧群提供原料奶以加工乳制品的资格的影响。方法2013年的散装储罐SCC数据是从爱尔兰的14个合作社收集的。计算每个日历月的SCC测试结果的几何平均值。然后，我们根据其每月几何平均SCC，计算了2013年爱尔兰的SCC三种类别（<200,000、200,000-400,000，> 400,000个细胞/ mL）的牛群数量和所供应的牛奶量。使用欧盟概述的方法，根据每个牧群的三个月滚动几何平均值，每月为其分配“供应资格”状态（始终合规，处于警告状态（第一次警告，第二次警告，第三次警告）并有可能被停职）和爱尔兰立法。使用两种方法来计算3个月的滚动几何平均值。然后，我们根据2013年爱尔兰的“有资格供应”资格确定了牛群的数量和牛奶供应量。所有计算均在进行和不进行季节性调整的情况下进行。结果对2,124,864条记录进行了分析，包括来自16,740个牛群的1,571,363条SCC测试结果。如果进行了季节性调整，则如果分别使用计算方法1或2，则在2013年应有860个（5.1％）或854个（5.1％）的羊群应被停职。如果除去季节性调整因素，则使用计算方法1估计可暂停的畜群数量将从860增加到974（增加13.2％），或者使用计算方法2从854增加到964（增加12.9％）。结论根据可用数据，不管用于计算3个月滚动几何平均值的方法如何，这种去除的模拟影响相对较小。当前研究的重点非常狭窄，有效期从2013年7月至2013年12月。因此，该结果低估了2013年有待暂停的牧群的总数。他们也可能低估了有待暂停的牧群的真实百分比变化，而没有考虑季节性公式。在2013年散装储罐SCC数据的相当大的百分比中，缺少国家牧群标识符，但是如果要将这些数据有意义地用于此目的或其他目的，则将需要该标识符。