The following procedures help to reduce contamination during sample collection. Equipment Sterile glass or disposable plastic vials with tight fitting push-on or screw caps are satisfactory. Vials of at least 15 ml capacity are usually most convenient to handle, but smaller vials may be used. Glass vials should be sterilized with the caps loosened during autoclaving, then tightened after the vials have cooled. Sample vials should be labelled with a waterproof marker to identify the cow and quarter.
Suitable racks are necessary for convenient handling of the vials.
Time of Sample Collection Samples for culture may be collected before or after milking or in the intermilking interval. The time chosen will frequently be the sampling time that is most convenient under the management conditions of the individual herd. However, if a somatic cell count or screening test that depends on the cell content of the milk is to be run, it is important to recognize that immediately after milking and for at least six hours thereafter, the cell count will be elevated above that present just before milking. Therefore, if cell counts or screening test results are to be compared, the sampling times relative to milking should be consistent. Preparing Udders and Teats Udders and especially teats must be clean and dry before sample collection is attempted.