O'Connell A, McParland S, Ruegg P L, O'Brien B, Gleeson D
Teagasc, Livestock Systems Research Department, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland; Department of Dairy Science, University of Wisconsin-Madison, Madison 53706.
Teagasc, Livestock Systems Research Department, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland.
J Dairy Sci. 2015 Jun;98(6):3778-90. doi: 10.3168/jds.2014-9001. Epub 2015 Mar 28.
The objectives of this study were to evaluate annual and seasonal trends in bulk tank somatic cell count (SCC), total bacterial count (TBC), and laboratory pasteurization count (LPC) in Ireland between 2007 and 2011 (inclusive), and to compare trends based on herd type and herd size. The unadjusted median SCC and TBC of all records were 266,000 and 17,000 cfu/mL, respectively. Data were transformed to log values and analyzed using a mixed model. Fixed effects included milk processor, year, month, and total monthly milk volume; milk producer was fitted as a random variable. After analysis, means were back transformed for interpretation. Annual SCC increased slightly from 259,000 cells/mL in 2007 to a peak of 272,647 cells/mL in 2009 and then declined slightly thereafter. Although statistically significant changes in annual TBC are probably not biologically relevant, values ranged between 23,922 and 26,290 cfu/mL. Annual LPC peaked in 2008 (265 cfu/mL), declined in 2009, and increased thereafter. Monthly mean SCC of all records increased from April onward, with the greatest increases seen from October to December, when the majority of cows entered late lactation. Monthly mean TBC exhibited a seasonal trend, whereby TBC was greatest at the beginning and end of the year, coinciding with winter housing. Seasonal milk production herds (n=8,002 herds) calve all cows in spring (February to April), whereas split-calving herds (n=1,829 herds) calve cows in the spring and autumn. From February to September, monthly SCC was lower for seasonal herds than for split-calving herds, whereas SCC was lower for split-calving herds for the remaining months. During winter (October to March), split-calving herds had lower monthly TBC than seasonal herds, most likely because of stricter regulations imposed upon them. Herd size was approximated using total annual milk production figures. Across all months, larger herds had lower SCC and TBC compared with smaller herds. No obvious improvements in milk quality were seen between 2007 and 2011. Farmers have the opportunity to improve milk quality by reducing bulk tank SCC in late lactation and by imposing stricter hygiene practices at the beginning and end of the year to overcome the seasonal variation of bulk tank TBC.
本研究的目的是评估2007年至2011年（含）爱尔兰散装罐体细胞计数（SCC）、总细菌计数（TBC）和实验室巴氏杀菌计数（LPC）的年度和季节性趋势，并比较基于畜群类型和畜群规模的趋势。所有记录的未调整SCC中位数和TBC分别为266,000和17,000 cfu/mL。数据转换为对数值并使用混合模型进行分析。固定效应包括牛奶加工商、年份、月份和每月总牛奶量；牛奶生产商作为随机变量。分析后，将均值进行逆变换以进行解释。年度SCC从2007年的259,000个细胞/mL略有增加，在2009年达到峰值272,647个细胞/mL，此后略有下降。尽管年度TBC的统计学显著变化可能在生物学上并不相关，但其值在23,922至26,290 cfu/mL之间。年度LPC在2008年达到峰值（265 cfu/mL），2009年下降，此后上升。所有记录的月度平均SCC从4月开始增加，10月至12月增加最为显著，此时大多数奶牛进入泌乳后期。月度平均TBC呈现季节性趋势，即TBC在年初和年末最大，与冬季圈养时间一致。季节性产奶牛群（n = 8,002个牛群）所有奶牛在春季（2月至4月）产犊，而分批产奶牛群（n = 1,829个牛群）奶牛在春季和秋季产犊。从2月到9月，季节性牛群的月度SCC低于分批产奶牛群，而在其余月份，分批产奶牛群的SCC较低。在冬季（10月至3月），分批产奶牛群的月度TBC低于季节性牛群，这很可能是因为对它们实施了更严格的规定。使用年度总牛奶产量数据估算畜群规模。在所有月份中，与较小的畜群相比，较大的畜群SCC和TBC较低。2007年至2011年期间未观察到牛奶质量有明显改善。奶农有机会通过降低泌乳后期散装罐SCC以及在年初和年末实施更严格的卫生措施来克服散装罐TBC的季节性变化，从而提高牛奶质量。
