Elmoslemany A M, Keefe G P, Dohoo I R, Jayarao B M
Department of Health Management, University of Prince Edward Island, Charlottetown, Prince Edward Island, C1A 4P3, Canada.
J Dairy Sci. 2009 Jun;92(6):2644-52. doi: 10.3168/jds.2008-1813.
A case-control study was conducted to identify specific on-farm risk factors that influence bacteriological quality of bulk tank milk in Prince Edward Island dairy herds. Total aerobic (TAC), preliminary incubation (PIC), laboratory pasteurization (LPC), and coliform (CC) counts were used to assess the bacteriological quality of bulk tank milk. Four case-control groups were defined based on the last 6 results of each test before on farm evaluation. A herd was classified as a TAC, PIC, or CC case when the herd had at least 4 high TAC, PIC, or CC counts out of the last 6 analyses for each test, respectively. For the LPC case group, a herd was required to have at least 3 high results out of the last 6 analyses. Control groups had low counts in the last 6 analyses for each test in the corresponding case group (TAC, PIC, CC, and LPC). The results of the study showed that TAC and PIC were mainly associated with cow and stall hygiene: washing the teats with water, not using teat predip, and dirty teats were risk factors. The LPC and CC were related to equipment hygiene, with high counts being associated with low temperature of the cleaning solution, high water-hardness score, and high alkalinity of alkaline detergent wash. Based on the findings of this study it can be concluded that TAC, PIC, LPC, and CC counts are of considerable value in identifying practices that could influence milk quality.
开展了一项病例对照研究，以确定影响爱德华王子岛奶牛场散装罐牛奶细菌学质量的特定农场风险因素。采用总需氧菌（TAC）、初步培养（PIC）、实验室巴氏杀菌（LPC）和大肠菌群（CC）计数来评估散装罐牛奶的细菌学质量。根据农场评估前每项检测的最后6次结果定义了4个病例对照组。当一个牛群在每项检测的最后6次分析中分别至少有4次TAC、PIC或CC计数偏高时，该牛群被归类为TAC、PIC或CC病例组。对于LPC病例组，要求一个牛群在最后6次分析中至少有3次结果偏高。对照组在相应病例组（TAC、PIC、CC和LPC）的每项检测的最后6次分析中计数较低。研究结果表明，TAC和PIC主要与奶牛和牛舍卫生有关：用水清洗乳头、不使用乳头预浸液以及乳头脏污是风险因素。LPC和CC与设备卫生有关，计数偏高与清洗液温度低、水硬度评分高以及碱性洗涤剂清洗的碱度高有关。根据本研究的结果可以得出结论，TAC、PIC、LPC和CC计数在识别可能影响牛奶质量的做法方面具有相当大的价值。
