Improved method for mastitis detection and evaluation of disinfectant efficiency during milking process. (CIGR Symposium Special Issue.)

摘要

In automatic milking systems, rapid methods to detect mastitis and also to prevent mastitis are very important since reduced milk quality and economic losses are the consequences of mastitis. Based on IDF Standard 148 a rapid and reliable method to detect somatic cell count with Coulter Counter technique was developed in this study and the efficiency of peracetic acid (PAA) to prevent bacterial cross-contamination was investigated using Escherichia coli as test microorganism. Besides conventional microbiological methods, flow cytometric analysis using carboxyfluorescein diacetate, thiazole orange, propidium iodide and DiOC₂(3) were applied using E. coli as test organism to study the efficiency of PAA. Acceleration of mastitis detection method was realised using centrifugation for lipid separation of foremilk samples before Coulter Counter measurements. During inflammation, an increase in somatic cell count was detected by Coulter Counter with a peak at particle sizes between 8 and 12 micro m. E. coli was reduced by 5.6 log cycles, 7.7 log cycles and 4.9 log cycles after 0.25% PAA treatment for 15 s at 0 degrees C, 10 degrees C and 20 degrees C. However, flow cytometric analysis showed that most of the cells are damaged but still have metabolic activity. The efficiency of PAA against mastitis-related bacteria was shown with plate count methods but flow cytometric analysis indicates that the cells may still have the potential to cause mastitis. The potential of Coulter Counter to detect somatic cell count within a short time was shown in this study. Important data regarding safety monitoring and quality control can be derived with this method.