Molineri Ana I, Signorini Marcelo L, Cuatrín Alejandra L, Canavesio Vilma R, Neder Verónica E, Russi Norma B, Bonazza Julio C, Calvinho Luis F
Facultad de Ciencias Veterinarias, Universidad Nacional del Litoral, Kreder 2805 (3080) Esperanza, Santa Fe, Argentina.
Rev Argent Microbiol. 2012 Jul-Sep;44(3):187-94.
The objective of this work was to determine on-farm risk factors for psychrotrophic bacterial counts in bulk tank milk from dairy farms in Argentina. Raw milk samples from bulk tanks of 27 dairy farms were examined for total psychrotrophic counts (TPC), proteolytic psychrotrophic counts (PPC) and lipolytic psychrotrophic counts (LPC) (dependent or outcome variables). A survey recording infrastructure conditions, milking equipment and milking management (independent variables) was performed. Bivariate association proofs and logistic regression analyses were used to determine association between independent variables and psychrotrophic bacterial counts. Milk cooled in plate heat exchangers or barrel tanks were 16.39 and 10.52 times more likely to yield TPC and PPC above the standard established for high quality milk compared with milk cooled in bulk tanks, respectively. Periodic cleaning of cooling tanks (3 times a week or daily) was associated with lower TPC (approximately 1.5 log CFU/ml) than weekly cleaning frequency and farms where milkers did not wash their hands during milking time were 7.81 times more likely to have higher PPC. No association was found between LPC and any of the independent variables. The only variable associated with TPC and PPC in a logistic regression model was the refrigeration system used on the farm. Dairy farms that possessed bulk milk cooling tanks yielded the lowest bacterial counts. Results of this study highlight the importance of both the type of cooling system used on the farm and its adequate hygienic maintenance for obtaining low pshychrotrophic counts at dairy farm.
这项工作的目的是确定阿根廷奶牛场储奶罐中嗜冷菌计数的农场风险因素。对27个奶牛场储奶罐中的生奶样本进行了总嗜冷菌计数（TPC）、蛋白水解嗜冷菌计数（PPC）和脂肪分解嗜冷菌计数（LPC）（因变量或结果变量）检测。开展了一项记录基础设施条件、挤奶设备和挤奶管理（自变量）的调查。采用双变量关联检验和逻辑回归分析来确定自变量与嗜冷菌计数之间的关联。与储奶罐冷却的牛奶相比，板式换热器或桶式罐冷却的牛奶产生高于优质牛奶标准的TPC和PPC的可能性分别高16.39倍和10.52倍。冷却罐定期清洁（每周3次或每天）与低于每周清洁频率的TPC较低（约1.5 log CFU/ml）相关，并且在挤奶时挤奶工不洗手的农场产生较高PPC的可能性高7.81倍。未发现LPC与任何自变量之间存在关联。逻辑回归模型中与TPC和PPC相关的唯一变量是农场使用的制冷系统。拥有储奶冷却罐的奶牛场细菌计数最低。本研究结果强调了农场使用的冷却系统类型及其适当的卫生维护对于在奶牛场获得低嗜冷菌计数的重要性。
